# Encoding with MEncoder

For the complete list of available MEncoder options and examples, please see the man page. For a series of hands-on examples and detailed guides on using several encoding parameters, read the encoding-tips that were collected from several mailing list threads on MPlayer-users. Search the archives for a wealth of discussions about all aspects of and problems related to encoding with MEncoder.

## Encoding two pass MPEG-4 ("DivX")

The name comes from the fact that this method encodes the file twice. The first encoding (dubbed pass) creates some temporary files (`*.log`) with a size of few megabytes, do not delete them yet (you can delete the AVI). In the second pass, the two pass output file is created, using the bitrate data from the temporary files. The resulting file will have much better image quality. If this is the first time you heard about this, you should consult some guides available on the net.

### copy audio track

Two pass encode of a DVD to an MPEG-4 ("DivX") AVI while copying the audio track.

    mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -oac copy -o movie.avi
    mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac copy -o movie.avi

### encode audio track

Two pass encode of a DVD to an MPEG-4 ("DivX") AVI while encoding the audio track to MP3.

    mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -oac mp3lame -lameopts vbr=3 -o movie.avi
    mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac mp3lame -lameopts vbr=3 -o movie.avi

## Encoding to MPEG format

MEncoder can create MPEG (MPEG-PS) format output files. It's probably useful only with libavcodec's mpeg1video codec, because players - except MPlayer - expect MPEG-1 video, and MPEG-1 layer 2 (MP2) audio streams in MPEG files.

This feature is not very useful right now, aside that it probably has many bugs, but the more importantly because MEncoder currently cannot encode MPEG-1 layer 2 (MP2) audio, which all other players expect in MPEG files.

To change MEncoder's output file format, use the `-of mpeg` option.

Example:

    mencoder -of mpeg -ovc lavc -lavcopts vcodec=mpeg1video -oac copy other_options media.avi -o output.mpg

## Rescaling movies

Often the need to resize movie images' size emerges. Its reasons can be many: decreasing file size, network bandwidth,etc. Most people even do rescaling when converting DVDs or SVCDs to DivX AVI. If you wish to rescale, read the Preserving aspect ratio section.

The scaling process is handled by the `scale` video filter: `-vf scale=width:height`. Its quality can be set with the `-sws` option. If it's not specified, MEncoder will use 2: bicubic.

Usage:

    mencoder input.mpg -ovc lavc -lavcopts vcodec=mpeg4 -vf scale=640:480 -o output.avi

## Stream copying

MEncoder can handle input streams in two ways: encode or copy them. This section is about copying.

- Video stream (option `-ovc copy`): nice stuff can be done :) Like, putting (not converting!) FLI or VIVO or MPEG-1 video into an AVI file! Of course only MPlayer can play such files :) And it probably has no real life value at all. Rationally: video stream copying can be useful for example when only the audio stream has to be encoded (like, uncompressed PCM to MP3).

- Audio stream (option `-oac copy`): straightforward. It is possible to take an external audio file (MP3, WAV) and mux it into the output stream. Use the `-audiofile filename` option for this.

## Encoding with the libavcodec codec family

libavcodec provides simple encoding to a lot of interesting video and audio formats. You can encode to the following codecs (more or less up to date):

Codec name | Description
--- | ---
mjpeg | Motion JPEG
ljpeg | Lossless JPEG
h263 | H.263
h263p | H.263+
mpeg4 | ISO standard MPEG-4 (DivX 5, XVID compatible)
msmpeg4 | pre-standard MPEG-4 variant by MS, v3 (AKA DivX3)
msmpeg4v2 | pre-standard MPEG-4 by MS, v2 (used in old asf files)
wmv1 | Windows Media Video, version 1 (AKA WMV7)
wmv2 | Windows Media Video, version 2 (AKA WMV8)
rv10 | an old RealVideo codec
mpeg1video | MPEG-1 video
mpeg2video | MPEG-2 video
huffyuv | lossless compression
asv1 | ASUS Video v1
asv2 | ASUS Video v2
ffv1 | FFmpeg's lossless video codec

The first column contains the codec names that should be passed after the `vcodec` config, like: `-lavcopts vcodec=msmpeg4`

An example, with MJPEG compression:

    mencoder dvd://2 -o title2.avi -ovc lavc -lavcopts vcodec=mjpeg -oac copy

## Encoding from multiple input image files (JPEG, PNG, TGA, SGI)

MEncoder is capable of creating movies from one or more JPEG, PNG or TGA files. With simple framecopy it can create MJPEG (Motion JPEG), MPNG (Motion PNG) or MTGA (Motion TGA) files.

### Explanation of the process:

1. MEncoder decodes the input image(s) with libjpeg (when decoding PNGs, it will use libpng).

2. MEncoder then feeds the decoded image to the chosen video compressor (DivX4, XviD, FFmpeg msmpeg4, etc.).

### Examples

The explanation of the `-mf` option is in the man page.

Creating an MPEG-4 file from all the JPEG files in the current directory:

    mencoder mf://*.jpg -mf w=800:h=600:fps=25:type=jpg -ovc lavc -lavcopts vcodec=mpeg4 -oac copy -o output.avi

Creating an MPEG-4 file from some JPEG files in the current directory:

    mencoder mf://frame001.jpg,frame002.jpg -mf w=800:h=600:fps=25:type=jpg -ovc lavc -lavcopts vcodec=mpeg4 -oac copy -o output.avi

Creating a Motion JPEG (MJPEG) file from all the JPEG files in the current directory:

    mencoder mf://*.jpg -mf w=800:h=600:fps=25:type=jpg -ovc copy -oac copy -o output.avi

Creating an uncompressed file from all the PNG files in the current directory:

    mencoder mf:// -mf w=800:h=600:fps=25:type=png -ovc raw -oac copy -o output.avi

Width must be integer multiple of 4, it's a limitation of the RAW RGB AVI format.

Creating a Motion PNG (MPNG) file from all the PNG files in the current directory:

    mencoder mf://*.png -mf w=800:h=600:fps=25:type=png -ovc copy -oac copy -o output.avi

Creating a Motion TGA (MTGA) file from all the TGA files in the current directory:

    mencoder mf://*.tga -mf w=800:h=600:fps=25:type=tga -ovc copy -oac copy -o output.avi

## Extracting DVD subtitles to VOBsub file

MEncoder is capable of extracting subtitles from a DVD into VOBsub formatted files. They consist of a pair of files ending in `.idx` and `.sub` and are usually packaged in a single `.rar` archive. MPlayer can play these with the `-vobsub` and `-vobsubid` options.

You specify the basename (i.e without the `.idx` or `.sub` extension) of the output files with `-vobsubout` and the index for this subtitle in the resulting files with `-vobsuboutindex`.

If the input is not from a DVD you should use `-ifo` to indicate the `.ifo` file needed to construct the resulting `.idx` file.

If the input is not from a DVD and you do not have the `.ifo` file you will need to use the `-vobsubid` option to let it know what language id to put in the `.idx` file.

Each run will append the running subtitle if the `.idx` and `.sub` files already exist. So you should remove any before starting.

### Copying two subtitles from a DVD while doing two pass encoding

    rm subtitles.idx subtitles.sub
    mencoder dvd://1 -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -vobsubout subtitles -vobsuboutindex 0 -sid 2
    mencoder dvd://1 -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -vobsubout subtitles -vobsuboutindex 1 -sid 5

### Copying a french subtitle from an MPEG file

    rm subtitles.idx subtitles.sub
    mencoder movie.mpg -ifo movie.ifo -vobsubout subtitles -vobsuboutindex 0 -vobsuboutid fr -sid 1

## Preserving aspect ratio

DVDs and SVCDs (i.e. MPEG-1/2) files contain an aspect ratio value, which describes how the player should scale the video stream, so humans won't have egg heads (ex.: 480x480 + 4:3 = 640x480). However when encoding to AVI (DivX) files, you have be aware that AVI headers don't store this value. Rescaling the movie is disgusting and time consuming, there has to be a better way!

There is

MPEG-4 has an unique feature: the video stream can contain its needed aspect ratio. Yes, just like MPEG-1/2 (DVD, SVCD) and H.263 files. Regretfully, there are no video players outside which support this attribute of MPEG-4, except MPlayer.

This feature can be used only with libavcodec's mpeg4 codec. Keep in mind: although MPlayer will correctly play the created file, other players will use the wrong aspect ratio.

You seriously should crop the black bands over and below the movie image. See the man page for the usage of the cropdetect and crop filters.

Usage

    mencoder sample-svcd.mpg -ovc lavc -lavcopts vcodec=mpeg4:autoaspect -vf crop=714:548:0:14 -oac copy -o output.avi

## Custom inter/intra matrices

With this feature of libavcodec you are able to set custom inter (I-frames/keyframes) and intra (P-frames/predicted frames) matrices. It is supported by many of the codecs: mpeg1video and mpeg2video are reported as working.

A typical usage of this feature is to set the matrices preferred by the KVCD specifications.

The KVCD "Notch" Quantization Matrix:

Intra:

     8  9 12 22 26 27 29 34
     9 10 14 26 27 29 34 37
    12 14 18 27 29 34 37 38
    22 26 27 31 36 37 38 40
    26 27 29 36 39 38 40 48
    27 29 34 37 38 40 48 58
    29 34 37 38 40 48 58 69
    34 37 38 40 48 58 69 79

Inter:

    16 18 20 22 24 26 28 30
    18 20 22 24 26 28 30 32
    20 22 24 26 28 30 32 34
    22 24 26 30 32 32 34 36
    24 26 28 32 34 34 36 38
    26 28 30 32 34 36 38 40
    28 30 32 34 36 38 42 42
    30 32 34 36 38 40 42 44

Usage:

    $ mencoder input.avi -o output.avi -oac copy -ovc lavc -lavcopts inter_matrix=...:intra_matrix=...

    $ mencoder input.avi -ovc lavc -lavcopts
    vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
    12,14,18,27,29,34,37,38,22,26,27,31,36,37,38,40,26,27,29,36,39,38,40,48,27,
    29,34,37,38,40,48,58,29,34,37,38,40,48,58,69,34,37,38,40,48,58,69,79
    :inter_matrix=16,18,20,22,24,26,28,30,18,20,22,24,26,28,30,32,20,22,24,26,
    28,30,32,34,22,24,26,30,32,32,34,36,24,26,28,32,34,34,36,38,26,28,30,32,34,
    36,38,40,28,30,32,34,36,38,42,42,30,32,34,36,38,40,42,44 -oac copy -o svcd.mpg

## Making a high quality MPEG-4 ("DivX") rip of a DVD movie

One frequently asked question is "How do I make the highest quality rip for a given size?". Another question is "How do I make the highest quality DVD rip possible? I don't care about file size, I just want the best quality."

The latter question is perhaps at least somewhat wrongly posed. After all, if you don't care about file size, why not simply copy the entire MPEG-2 video stream from the the DVD? Sure, your AVI will end up being 5GB, give or take, but if you want the best quality and don't care about size, this is certainly your best option.

In fact, the reason you want to transcode a DVD into MPEG-4 is specifically because you do care about file size.

It's difficult to offer a cookbook recipe on how to create a very high quality DVD rip. There are several factors to consider, and you should understand these details or else you're likely to end up disappointed with your results. Below we'll investigate some of these issues, and then have a look at an example. We assume you're using libavcodec to encode the video, although the theory applies to other codecs as well.

If this seems to be too much for you, you should probably use one of the many fine frontends that are listed in the MEncoder section of our related projects page. That way, you should be able to achieve high quality rips without too much thinking, because most of those tools are designed to take clever decisions for you.

### Constant Quantizer vs. two pass

There are three approaches to encoding the video: constant bitrate (CBR), constant quantizer, and two pass (ABR, or average bitrate).

In each of these modes, libavcodec breaks the video frame into 16x16 pixel macroblocks and then applies a quantizer to each macroblock. The lower the quantizer, the better the quality and higher the bitrate. The method libavcodec uses to determine which quantizer to use for a given macroblock varies and is highly tunable. (This is an extreme over-simplification of the actual process, but the basic concept is useful to understand.)

When you specify a constant bitrate, libavcodec will encode the video, discarding detail as much as necessary and as little as possible in order to remain lower than the given bitrate. If you truly don't care about file size, you could as well use CBR and specify a bitrate of infinity. (In practice, this means a value high enough so that it poses no limit, like 10000Kbit.) With no real restriction on bitrate, the result is that libavcodec will use the lowest possible quantizer for each macroblock (as specified by `vqmin`, which is 2 by default). As soon as you specify a low enough bitrate that libavcodec is forced to use a higher quantizer, then you're almost certainly ruining the quality of your video. In order to avoid that, you should probably downscale your video, according to the method described later on in this guide. In general, you should avoid CBR altogether if you care about quality.

With constant quantizer, libavcodec uses the same quantizer, as specified by the `vqscale` option, on every macroblock. If you want the highest quality rip possible, again ignoring bitrate, you can use `vqscale=2`. This will yield the same bitrate and PSNR (peak signal-to-noise ratio) as CBR with `vbitrate`=infinity and the default `vqmin` of 2.

The problem with constant quantizing is that it uses the given quantizer whether the macroblock needs it or not. That is, it might be possible to use a higher quantizer on a macroblock without sacrificing visual quality. Why waste the bits on an unnecessarily low quantizer? Your CPU has as many cycles as there is time, but there's only so many bits on your hard disk.

With a two pass encode, the first pass will rip the movie as though it were CBR, but it will keep a log of properties for each frame. This data is then used during the second pass in order to make intelligent decisions about which quantizers to use. During fast action or low detail scenes, higher quantizers will likely be used, and during slow moving or high detail scenes, lower quantizers will be used.

If you use `vqscale=2`, then you're wasting bits. If you use `vqscale=3`, then you're not getting the highest quality rip. Suppose you rip a DVD at `vqscale=3`, and the result is 1800Kbit. If you do a two pass encode with `vbitrate=1800`, the resulting video will have higher quality for the same bitrate.

Since you're now convinced that two pass is the way to go, the real question now is what bitrate to use? The answer is that there's no single answer. Ideally you want to choose a bitrate that yields the best balance between quality and file size. This is going to vary depending on the source video.

If size doesn't matter, a good starting point for a very high quality rip is about 2000Kbit plus or minus 200Kbit. For fast action or high detail source video, or if you just have a very critical eye, you might decide on 2400 or 2600. For some DVDs, you might not notice a difference at 1400Kbit. It's a good idea to experiment with scenes at different bitrates to get a feel.

If you aim at a certain size, you will have to somehow calculate the bitrate. But before that, you need to know how much space you should reserve for the audio track(s), so you should rip those first. You can compute the bitrate with the following equation: bitrate = (target_size_in_Mbytes - sound_size_in_Mbytes) * 1024 * 1024 / length_in_secs * 8 / 1000 For instance, to squeeze a two-hour movie onto a 702MB CD, with 60MB of audio track, the video bitrate will have to be: (702 - 60) * 1024 * 1024 / (120*60) * 8 / 1000 = 740kbps

### Constraints for efficient encoding

Due to the nature of MPEG-type compression, there are various constraints you should follow for maximal quality. MPEG splits the video up into 16x16 squares called macroblocks, each composed of 4 8x8 blocks of luma (intensity) information and two half-resolution 8x8 chroma (color) blocks (one for red-cyan axis and the other for the blue-yellow axis). Even if your movie width and height are not multiples of 16, the encoder will use enough 16x16 macroblocks to cover the whole picture area, and the extra space will go to waste. So in the interests of maximizing quality at a fixed filesize, it is a bad idea to use dimensions that are not multiples of 16.

Most DVDs also have some degree of black borders at the edges. Leaving these in place can hurt quality in several ways.

1. MPEG-type compression is also highly dependent on frequency domain transformations, in particular the Discrete Cosine Transform (DCT), which is similar to the Fourier transform. This sort of encoding is efficient for representing patterns and smooth transitions, but it has a hard time with sharp edges. In order to encode them it must use many more bits, or else an artifact known as ringing will appear.

   The frequency transform (DCT) takes place separately on each macroblock (actually each block), so this problem only applies when the sharp edge is inside a block. If your black borders begin exactly at multiple-of-16 pixel boundaries, this is not a problem. However, the black borders on DVDs rarely come nicely aligned, so in practice you will always need to crop to avoid this penalty.

In addition to frequency domain transforms, MPEG-type compression uses motion vectors to represent the change from one frame to the next. Motion vectors naturally work much less efficiently for new content coming in from the edges of the picture, because it is not present in the previous frame. As long as the picture extends all the way to the edge of the encoded region, motion vectors have no problem with content moving out the edges of the picture. However, in the presence of black borders, there can be trouble:

1. For each macroblock, MPEG-type compression stores a vector identifying which part of the previous frame should be copied into this macroblock as a base for predicting the next frame. Only the remaining differences need to be encoded. If a macroblock spans the edge of the picture and contains part of the black border, then motion vectors from other parts of the picture will overwrite the black border. This means that lots of bits must be spent either re-blackening the border that was overwritten, or (more likely) a motion vector won't be used at all and all the changes in this macroblock will have to be coded explicitly. Either way, encoding efficiency is greatly reduced.

   Again, this problem only applies if black borders do not line up on multiple-of-16 boundaries.

2. Finally, suppose we have a macroblock in the interior of the picture, and an object is moving into this block from near the edge of the image. MPEG-type coding can't say "copy the part that's inside the picture but not the black border." So the black border will get copied inside too, and lots of bits will have to be spent encoding the part of the picture that's supposed to be there.

   If the picture runs all the way to the edge of the encoded area, MPEG has special optimizations to repeatedly copy the pixels at the edge of the picture when a motion vector comes from outside the encoded area. This feature becomes useless when the movie has black borders. Unlike problems 1 and 2, aligning the borders at multiples of 16 does not help here.

3. Depite the borders being entirely black and never changing, there is at least a minimal amount of overhead involved in having more macroblocks.

For all of these reasons, it's recommended to fully crop black borders. Further, if there is an area of noise/distortion at the edge of the picture, cropping this will improve encoding efficiency as well. Videophile purists who want to preserve the original as close as possible may object to this cropping, but unless you plan to encode at constant quantizer, the quality you gain from cropping will considerably exceed the amount of information lost at the edges.

### Cropping and Scaling

Native DVD resolution is 720x480 for NTSC, and 720x576 for PAL, but there's an aspect flag that specifies whether it's full-screen (4:3) or wide-screen (16:9). Many (if not most) widescreen DVDs are not strictly 16:9, and will be either 1.85:1 or 2.35:1 (cinescope). This means that there will be black bands in the video that will need to be cropped out.

MPlayer provides a crop detection filter that will determine the crop rectangle (`-vf cropdetect`). Because MPEG-4 uses 16x16 macroblocks, you'll want to make sure that each dimension of the video you're encoding is a multiple of 16 or else you will be degrading quality, especially at lower bitrates. You can do this by rounding the width and height of the crop rectangle down to the nearest multiple of 16. When cropping, you'll want to increase the y-offset by half the difference of the old and the new height so that the resulting video is taken from the center of the frame. And because of the way DVD video is sampled, make sure the offset is an even number. (In fact, as a rule, never use odd values for any parameter when you're cropping and scaling video.) If you're not comfortable throwing a few extra pixels away, you might prefer instead to scale the video instead. We'll look at this in our example below. You can actually let the `cropdetect` filter do all of the above for you, as it has an optional `round` parameter that is equal to 16 by default.

Also, be careful about "half black" pixels at the edges. Make sure you crop these out too, or else you'll be wasting bits there that are better spent elsewhere.

After all is said and done, you'll probably end up with video whose pixels aren't quite 1.85:1 or 2.35:1, but rather something close to that. You could calculate the new aspect ratio manually, but MEncoder offers an option for libavcodec called `autoaspect` that will do this for you. Absolutely do not scale this video up in order to square the pixels unless you like to waste your hard disk space. Scaling should be done on playback, and the player will use the aspect stored in the AVI to determine the correct resolution. Unfortunately, not all players enforce this auto-scaling information, therefore you may still want to rescale.

First, you should compute the encoded aspect ratio: ARc = (Wc x (ARa / PRdvd )) / Hc

#### where:

- Wc and Hc are the width and height of the cropped video,

- PRdvd is the pixel ratio of the DVD wich is equal to 1.25=(720/576) for PAL,

- DVDs and 1.5=(720/480) for NTSC DVDs,

Then, you can compute the X and Y resolution, according to a certain Compression Quality (CQ) factor: ResY = INT(SQRT( 1000*Bitrate/25/ARc/CQ )/16) * 16 ResX = INT( ResY * ARc / 16) * 16

Okay, but what is the CQ? The CQ represents the number of bits per pixel and per frame of the encode. Roughly speaking, the greater the CQ, the less the likelihood to see encoding artifacts. However, if you have a target size for your movie (1 or 2 CDs for instance), there's a limited total number of bits that you can spend; therefore it's necessary to find a good tradeoff between compressibility and quality.

The CQ depends both on the bitrate and the movie resolution. In order to raise the CQ, typically you'd downscale the movie given that the bitrate is computed in function of the target size and the length of the movie, which are constant. A CQ below 0.18 usually ends up in a very blocky picture, because there aren't enough bits to code the information of each macroblock (MPEG4, like many other codecs, groups pixels by blocks of several pixels to compress the image; if there aren't enough bits, the edges of those blocks are visible). It's therefore wise to take a CQ ranging from 0.20 to 0.22 for a 1 CD rip, and 0.26-0.28 for 2 CDs.

Please take note that the CQ is just an indicative figure, as depending on the encoded content, a CQ of 0.18 may look just fine for a Bergman, contrary to a movie such as The Matrix, which contains many high-motion scenes. On the other hand, it's worthless to raise CQ higher than 0.30 as you'd be wasting bits without any noticeable quality gain.

### Audio

Audio is a much simpler problem to solve: if you care about quality, just leave it as is. Even AC3 5.1 streams are at most 448Kbit/s, and they're worth every bit. You might be tempted to transcode the audio to high quality Vorbis, but just because you don't have an A/V receiver for AC3 pass-through today doesn't mean you won't have one tomorrow. Future-proof your DVD rips by preserving the AC3 stream. You can keep the AC3 stream either by copying it directly into the video stream during the encoding. You can also extract the AC3 stream in order to mux it into containers such as NUT or Matroska.

    mplayer source_file.vob -aid 129 -dumpaudio -dumpfile sound.ac3

will dump into the file sound.ac3 the audio track number 129 from the file source_file.vob (NB: DVD VOB files usually use a different audio numbering, which means that the VOB audio track 129 is the 2nd audio track of the file).

But sometimes you truly have no choice but to further compress the sound so that more bits can be spent on the video. Most people choose to compress audio with either MP3 or Vorbis audio codecs. While the latter is a very space-efficient codec, MP3 is better supported by hardware players, although this trend is changing.

First of all, you will have to convert the DVD sound into a WAV file that the audio codec can use as input. For example:

    mplayer source_file.vob -ao pcm:file=destination_sound.wav -vc dummy -aid 1 -vo null

will dump the second audio track from the file source_file.vob into the file destination_sound.wav. You may want to normalize the sound before encoding, as DVD audio tracks are commonly recorded at low volumes. You can use the tool normalize for instance, which is available in most distributions. If you're using Windows, a tool such as BeSweet can do the same job. You will compress in either Vorbis or MP3. For example:

    oggenc -q1 destination_sound.wav

will encode destination_sound.wav with the encoding quality 1, which is roughly equivalent to 80Kb/s, and is the minimum quality at which you should encode if you care about quality. Please note that MEncoder currently cannot mux Vorbis audio tracks into the output file because it only supports AVI and MPEG containers as an output, each of which may lead to audio/video playback synchronization problems with some players when the AVI file contain VBR audio streams such as Vorbis. Don't worry, this document will show you how you can do that with third party programs.

### Interlacing and Telecine

Almost all movies are shot at 24 fps. Because NTSC is 30000/1001 fps, some processing must be done to this 24 fps video to make it run at the correct NTSC framerate. The process is called 3:2 pulldown, commonly referred to as telecine (because pulldown is often applied during the telecine process), and, naively described, it works by slowing the film down to 24000/1001 fps, and repeating every fourth frame.

No special processing, however, is done to the video for PAL DVDs, which run at 25 fps. (Technically, PAL can be telecined, called 2:2 pulldown, but this doesn't become an issue in practice.) The 24 fps film is simply played back at 25 fps. The result is that the movie runs slightly faster, but unless you're an alien, you probably won't notice the difference. Most PAL DVDs have pitch-corrected audio, so when they're played back at 25 fps things will sound right, even though the audio track (and hence the whole movie) has a running time that's 4% less than NTSC DVDs.

Because the video in a PAL DVD hasn't been altered, you needn't worry much about frame rate. The source is 25 fps, and your rip will be 25 fps. However, if you're ripping an NTSC DVD movie, you may need to apply inverse telecine.

For movies shot at 24 fps, the video on the NTSC DVD is either telecined 30000/1001, or else it is progressive 24000/1001 fps and intended to be telecined on-the-fly by a DVD player. On the other hand, TV series are usually only interlaced, not telecined. This is not a hard rule: some TV series are interlaced (such as Buffy the Vampire Slayer) whereas some are a mixture of progressive and interlaced (such as Angel, or 24).

It's highly recommended that you read the section on How to deal with telecine and interlacing in NTSC DVDs to learn how to handle the different possibilities.

However, if you're mostly just ripping movies, likely you're either dealing with 24 fps progressive or telecined video, in which case you can use the `pullup` filter `-vf pullup,softskip`.

### Filtering

In general, you want to do as little filtering as possible to the movie in order to remain close to the original DVD source. Cropping is often necessary (as described above), but do not scale the video. Although scaling down is sometimes preferred to using higher quantizers, we want to avoid both these things: remember that we decided from the start to trade bits for quality.

Also, do not adjust gamma, contrast, brightness, etc. What looks good on your display may not look good on others. These adjustments should be done on playback only.

One thing you might want to do, however, is pass the video through a very light denoise filter, such as `-vf hqdn3d=2:1:2`. Again, it's a matter of putting those bits to better use: why waste them encoding noise when you can just add that noise back in during playback? Increasing the parameters for `hqdn3d` will further improve compressibility, but if you increase the values too much, you risk degrading the image visibily. The suggested values above (`2:1:2`) are quite conservative; you should feel free to experiment with higher values and observe the results for yourself.

### Encoding options of libavcodec

Ideally, you'd probably want to be able to just tell the encoder to switch into "high quality" mode and move on. That would probably be nice, but unfortunately hard to implement as different encoding options yield different quality results depending on the source material. That's because compression depends on the visual properties of the video in question. For example, anime and live action have very different properties and thus require different options to obtain optimum encoding. The good news is that some options should never be left out, like `mbd=2`, `trell`, and `v4mv`. See below for a detailed description of common encoding options.

#### Options to adjust:

- vmax_b_frames: 1 or 2 is good, depending on the movie. Note that libavcodec does not yet support closed GOP (the option `cgop` doesn't currently work), so DivX5 won't be able to decode anything encoded with B-frames.

- vb_strategy=1: helps in high-motion scenes. Requires vmax_b_frames >= 2. On some videos, vmax_b_frames may hurt quality, but vmax_b_frames=2 along with vb_strategy=1 helps.

- dia: motion search range. Bigger is better and slower. Negative values are a completely different scale. Good values are -1 for a fast encode, or 2-4 for slower.

- predia: motion search pre-pass. Not as important as dia. Good values are 1 (default) to 4. Requires preme=2 to really be useful.

- cmp, subcmp, precmp: Comparison function for motion estimation. Experiment with values of 0 (default), 2 (hadamard), 3 (dct), and 6 (rate distortion). 0 is fastest, and sufficient for precmp. For cmp and subcmp, 2 is good for anime, and 3 is good for live action. 6 may or may not be slightly better, but is slow.

- last_pred: Number of motion predictors to take from the previous frame. 1-3 or so help at little speed cost. Higher values are slow for no extra gain.

- cbp, mv0: Controls the selection of macroblocks. Small speed cost for small quality gain.

- qprd: adaptive quantization based on the macroblock's complexity. May help or hurt depending on the video and other options. This can cause artifacts unless you set vqmax to some reasonably small value (6 is good, maybe as low as 4); vqmin=1 should also help.

- qns: very slow, especially when combined with qprd. This option will make the encoder minimize noise due to compression artifacts instead of making the encoded video strictly match the source. Don't use this unless you've already tweaked everything else as far as it will go and the results still aren't good enough.

- vqcomp: Tweak ratecontrol. What values are good depends on the movie. You can safely leave this alone if you want. Reducing vqcomp puts more bits on low-complexity scenes, increasing it puts them on high-complexity scenes (default: 0.5, range: 0-1. recommended range: 0.5-0.7).

- vlelim, vcelim: Sets the single coefficient elimination threshold for luminance and chroma planes. These are encoded separately in all MPEG-like algorithms. The idea behind these options is to use some good heuristics to determine when the change in a block is less than the threshold you specify, and in such a case, to just encode the block as "no change". This saves bits and perhaps speeds up encoding. vlelim=-4 and vcelim=9 seem to be good for live movies, but seem not to help with anime; when encoding animation, you should probably leave them unchanged.

- qpel: Quarter pixel motion estimation. MPEG-4 uses half pixel precision for its motion search by default, therefore this option comes with an overhead as more information will be stored in the encoded file. The compression gain/loss depends on the movie, but it's usually not very effective on anime. qpel always incurs a significant cost in CPU decode time (+20% in practice).

- psnr: doesn't affect the actual encoding, but writes a log file giving the type/size/quality of each frame, and prints a summary of PSNR (Peak Signal to Noise Ratio) at the end.

#### Options not recommended to play with:

- vme: The default is best.

- lumi_mask, dark_mask: Psychovisual adaptive quantization. You don't want to play with those options if you care about quality. Reasonable values may be effective in your case, but be warned this is very subjective.

- scplx_mask: Tries to prevent blocky artifacts, but postprocessing is better.

### Example

So, you've just bought your shiny new copy of Harry Potter and the Chamber of Secrets (widescreen edition, of course), and you want to rip this DVD so that you can add it to your Home Theatre PC. This is a region 1 DVD, so it's NTSC. The example below will still apply to PAL, except you'll omit `-ofps 24000/1001` (because the output framerate is the same as the input framerate), and of course the crop dimensions will be different.

After running `mplayer dvd://1`, we follow the process detailed in the section How to deal with telecine and interlacing in NTSC DVDs and discover that it's 24000/1001 fps progressive video, which means that we needn't use an inverse telecine filter, such as `pullup` or `filmdint`.

Next, we want to determine the appropriate crop rectangle, so we use the cropdetect filter:

    mplayer dvd://1 -vf cropdetect

Make sure you seek to a fully filled frame (such as a bright scene), and you'll see in MPlayer's console output:

    crop area: X: 0..719  Y: 57..419  (-vf crop=720:362:0:58)

We then play the movie back with this filter to test its correctness:

    mplayer dvd://1 -vf crop=720:362:0:58

And we see that it looks perfectly fine. Next, we ensure the width and height are a multiple of 16. The width is fine, however the height is not. Since we didn't fail 7th grade math, we know that the nearest multiple of 16 lower than 362 is 352.

We could just use `crop=720:352:0:58`, but it'd be nice to take a little off the top and a little off the bottom so that we retain the center. We've shrunk the height by 10 pixels, but we don't want to increase the y-offset by 5-pixels since that's an odd number and will adversely affect quality. Instead, we'll increase the y-offset by 4 pixels:

    mplayer dvd://1 -vf crop=720:352:0:62

Another reason to shave pixels from both the top and the bottom is that we ensure we've eliminated any half-black pixels if they exist. Note that if your video is telecined, make sure the `pullup` filter (or whichever inverse telecine filter you decide to use) appears in the filter chain before you crop. If it is interlaced, deinterlace before cropping. (If you choose to preserve the interlaced video, then make sure your vertical crop offset is a multiple of 4.)

If you're really concerned about losing those 10 pixels, you might prefer instead to scale the dimensions down to the nearest multiple of 16. The filter chain would look like:

    -vf crop=720:362:0:58,scale=720:352

Scaling the video down like this will mean that some small amount of detail is lost, though it probably won't be perceptible. Scaling up will result in lower quality (unless you increase the bitrate). Cropping discards those pixels altogether. It's a tradeoff that you'll want to consider for each circumstance. For example, if the DVD video was made for television, you might want to avoid vertical scaling, since the line sampling corresponds to the way the content was originally recorded.

On inspection, we see that our movie has a fair bit of action and high amounts of detail, so we pick 2400Kbit for our bitrate.

We're now ready to do the two pass encode. Pass one:

    mencoder dvd://1 -ofps 24000/1001 -oac copy -vf crop=720:352:0:62,hqdn3d=2:1:2 -ovc lavc \
    -lavcopts vcodec=mpeg4:vbitrate=2400:v4mv:mbd=2:trell:cmp=3:subcmp=3:mbcmp=3:autoaspect:vpass=1 \
    -o Harry_Potter_2.avi

And pass two is the same, except that we specify `vpass=2`:

    mencoder dvd://1 -ofps 24000/1001 -oac copy -vf crop=720:352:0:62,hqdn3d=2:1:2 -ovc lavc \
    -lavcopts vcodec=mpeg4:vbitrate=2400:v4mv:mbd=2:trell:cmp=3:subcmp=3:mbcmp=3:autoaspect:vpass=2 \
    -o Harry_Potter_2.avi

The options `v4mv:mbd=2:trell` will greatly increase the quality at the expense of encoding time. There's little reason to leave these options out when the primary goal is quality. The options `cmp=3:subcmp=3:mbcmp=3` select a comparison function that yields higher quality than the defaults. You might try experimenting with this parameter (refer to the man page for the possible values) as different functions can have a large impact on quality depending on the source material. For example, if you find libavcodec produces too much blocky artifacting, you could try selecting the experimental NSSE as comparison function via `*cmp=10`.

For this movie, the resulting AVI will be 138 minutes long and nearly 3GB. And because you said that file size doesn't matter, this is a perfectly acceptable size. However, if you had wanted it smaller, you could try a lower bitrate. Increasing bitrates have diminishing returns, so while we might clearly see an improvement from 1800Kbit to 2000Kbit, it might not be so noticeable above 2000Kbit. Feel free to experiment until you're happy.

Because we passed the source video through a denoise filter, you may want to add some of it back during playback. This, along with the `spp` post-processing filter, drastically improves the perception of quality and helps eliminate blocky artifacts in the video. With MPlayer's `autoq` option, you can vary the amount of post-processing done by the spp filter depending on available CPU. Also, at this point, you may want to apply gamma and/or color correction to best suit your display. For example:

    mplayer Harry_Potter_2.avi -vf spp,noise=9ah:5ah,eq2=1.2 -autoq 3

### Muxing

Now that you have encoded your video, you will most likely want to mux it with one or more audio tracks into a movie container, such as AVI, MPEG, Matroska or NUT. MEncoder is currently only able to output audio and video into MPEG and AVI container formats. for example:

    mencoder -oac copy -ovc copy  -o output_movie.avi -audiofile input_audio.mp2 input_video.avi

This would merge the video file input_video.avi and the audio file input_audio.mp2 into the AVI file output_movie.avi. This command works with MPEG-1 layer I, II and III (more commonly known as MP3) audio, WAV and a few other audio formats too.

MEncoder features experimental support for libavformat, which is a library from the FFmpeg project that supports muxing and demuxing a variety of containers. For example:

    mencoder -oac copy -ovc copy  -o output_movie.asf -audiofile input_audio.mp2 input_video.avi -of lavf -lavfopts format=asf

This will do the same thing as the previous example, except that the output container will be ASF. Please note that this support is highly experimental (but getting better every day), and will only work if you compiled MPlayer with the support for libavformat enabled (which means that a pre-packaged binary version will not work in most cases).

#### Limitations of the AVI container

Although it is the most widely-supported container format after MPEG-1, AVI also has some major drawbacks. Perhaps the most obvious is the overhead. For each chunk of the AVI file, 24 bytes are wasted on headers and index. This translates into a little over 5 MB per hour, or 1-2.5% overhead for a 700 MB movie. This may not seem like much, but it could mean the difference between being able to use 700 kbit/sec video or 714 kbit/sec, and every bit of quality counts.

In addition this gross inefficiency, AVI also has the following major limitations:

1. Only fixed-fps content can be stored. This is particularly limiting if the original material you want to encode is mixed content, for example a mix of NTSC video and film material. Actually there are hacks that can be used to store mixed-framerate content in AVI, but they increase the (already huge) overhead fivefold or more and so are not practical.

2. Audio in AVI files must be either constant-bitrate (CBR) or constant-framesize (i.e. all frames decode to the same number of samples). Unfortunately, the most efficient codec, Vorbis, does not meet either of these requirements. Therefore, if you plan to store your movie in AVI, you'll have to use a less efficient codec such as MP3 or AC3.

Having said all that, MEncoder does not currently support variable-fps output or Vorbis encoding. Therefore, you may not see these as limitations if MEncoder is the only tool you will be using to produce your encodes. However, it is possible to use MEncoder only for video encoding, and then use external tools to encode audio and mux it into another container format.

#### Muxing into the Matroska container

Matroska is a free, open standard container format, aiming to offer a lot of advanced features, which older containers like AVI cannot handle. For example, Matroska supports variable bitrate audio content (VBR), variable framerates (VFR), chapters, file attachments, error detection code (EDC) and modern A/V Codecs like "Advanced Audio Coding" (AAC), "Vorbis" or "MPEG-4 AVC" (H.264), next to nothing handled by AVI.

The tools required to create Matroska files are collectively called mkvtoolnix, and are available for most Unix platforms as well as Windows. Because Matroska is an open standard you may find other tools that suit you better, but since mkvtoolnix is the most common, and is supported by the Matroska team itself, we will only cover its usage.

Probably the easiest way to get started with Matroska is to use MMG, the graphical frontend shipped with mkvtoolnix, and follow the guide to mkvmerge GUI (mmg)

You may also mux audio and video files using the command line:

    mkvmerge -o output.mkv input_video.avi input_audio1.mp3 input_audio2.ac3

This would merge the video file input_video.avi and the two audio files input_audio1.mp3 and input_audio2.ac3 into the Matroska file output.mkv. Matroska, as mentioned earlier, is able to do much more than that, like multiple audio tracks (including fine-tuning of audio/video synchronization), chapters, subtitles, splitting, etc... Please refer to the documentation of those applications for more details.

## How to deal with telecine and interlacing within NTSC DVDs

### Introduction

#### What is telecine?

I suggest you visit this page if you don't understand much of what is written in this document: http://www.divx.com/support/guides/guide.php?gid=10 This URL links to an understandable and reasonably comprehensive description of what telecine is.

#### A note about the numbers.

Many documents, including the guide linked above, refer to the fields per second value of NTSC video as 59.94 and the corresponding frames per second values as 29.97 (for telecined and interlaced) and 23.976 (for progressive). For simplicity, some documents even round these numbers to 60, 30, and 24.

Strictly speaking, all those numbers are approximations. Black and white NTSC video was exactly 60 fields per second, but 60000/1001 was later chosen to accomodate color data while remaining compatible with contemporary black and white televisions. Digital NTSC video (such as on a DVD) is also 60000/1001 fields per second. From this, interlaced and telecined video are derived to be 30000/1001 frames per second; progressive video is 24000/1001 frames per second.

Older versions of the MEncoder documentation and many archived mailing list posts refer to 59.94, 29.97, and 23.976. All MEncoder documentation has been updated to use the fractional values, and you should use them too.

`-ofps 23.976` is incorrect. `-ofps 24000/1001` should be used instead.

#### How telecine is used.

All video intended to be displayed on an NTSC television set must be 60000/1001 fields per second. Made-for-TV movies and shows are often filmed directly at 60000/1001 fields per second, but the majority of cinema is filmed at 24 or 24000/1001 frames per second. When cinematic movie DVDs are mastered, the video is then converted for television using a process called telecine.

On a DVD, the video is never actually stored as 60000/1001 fields per second. For video that was originally 60000/1001, each pair of fields is combined to form a frame, resulting in 30000/1001 frames per second. Hardware DVD players then read a flag embedded in the video stream to determine whether the odd- or even-numbered lines should form the first field.

Usually, 24000/1001 frames per second content stays as it is when encoded for a DVD, and the DVD player must perform telecining on-the-fly. Sometimes, however, the video is telecined before being stored on the DVD; even though it was originally 24000/1001 frames per second, it becomes 60000/1001 fields per second. When it is stored on the DVD, pairs of fields are combined to form 30000/1001 frames per second.

When looking at individual frames formed from 60000/10001 fields per second video, telecined or otherwise, interlacing is clearly visible wherever there is any motion, because one field (say, the even-numbered lines) represents a moment in time 1/(60000/1001) seconds later than the other. Playing interlaced video on a computer looks ugly both because the monitor is higher resolution and because the video is shown frame-after-frame instead of field-after-field.

#### Notes:

- This section only applies to NTSC DVDs, and not PAL.

- The example MEncoder lines throughout the document are not intended for actual use. They are simply the bare minimum required to encode the pertaining video category. How to make good DVD rips or fine-tune libavcodec for maximal quality is not within the scope of this document.

- There are a couple footnotes specific to this guide, linked like this: [1]

### How to tell what type of video you have

#### Progressive

Progressive video was originally filmed at 24000/1001 fps, and stored on the DVD without alteration.

When you play a progressive DVD in MPlayer, MPlayer will print the following line as soon as the movie begins to play:

     demux_mpg: 24000/1001 fps progressive NTSC content detected, switching framerate.

From this point forward, demux_mpg should never say it finds "30000/1001 fps NTSC content."

When you watch progressive video, you should never see any interlacing. Beware, however, because sometimes there is a tiny bit of telecine mixed in where you wouldn't expect. I've encountered TV show DVDs that have one second of telecine at every scene change, or at seemingly random places. I once watched a DVD that had a progressive first half, and the second half was telecined. If you want to be really thorough, you can scan the entire movie:

    mplayer dvd://1 -nosound -vo null -benchmark

Using `-benchmark` makes MPlayer play the movie as quickly as it possibly can; still, depending on your hardware, it can take a while. Every time demux_mpg reports a framerate change, the line immediately above will show you the time at which the change occurred.

Sometimes progressive video on DVDs is referred to as "soft-telecine" because it is intended to be telecined by the DVD player.

#### Telecined

Telecined video was originally filmed at 24000/1001, but was telecined before it was written to the DVD.

MPlayer does not (ever) report any framerate changes when it plays telecined video.

Watching a telecined video, you will see interlacing artifacts that seem to "blink": they repeatedly appear and disappear. You can look closely at this by

1.     mplayer dvd://1

2. Seek to a part with motion.

3. Use the . key to step forward one frame at a time.

4. Look at the pattern of interlaced-looking and progressive-looking frames. If the pattern you see is PPPII,PPPII,PPPII,... then the video is telecined. If you see some other pattern, then the video may have been telecined using some non-standard method; MEncoder cannot losslessly convert non-standard telecine to progressive. If you don't see any pattern at all, then it is most likely interlaced.

Sometimes telecined video on DVDs is referred to as "hard-telecine". Since hard-telecine is already 60000/1001 fields per second, the DVD player plays the video without any manipulation.

#### Interlaced

Interlaced video was originally filmed at 60000/1001 fields per second, and stored on the DVD as 30000/1001 frames per second. The interlacing effect (often called "combing") is a result of combining pairs of fields into frames. Each field is supposed to be 1/(60000/1001) seconds apart, and when they are displayed simultaneously the difference is apparent.

As with telecined video, MPlayer should not ever report any framerate changes when playing interlaced content.

When you view an interlaced video closely by frame-stepping with the . key, you will see that every single frame is interlaced.

#### Mixed progressive and telecine

All of a "mixed progressive and telecine" video was originally 24000/1001 frames per second, but some parts of it ended up being telecined.

When MPlayer plays this category, it will (often repeatedly) switch back and forth between "30000/1001 fps NTSC" and "24000/1001 fps progressive NTSC". Watch the bottom of MPlayer's output to see these messages.

You should check the "30000/1001 fps NTSC" sections to make sure they are actually telecine, and not just interlaced.

#### Mixed progressive and interlaced

In "mixed progressive and interlaced" content, progressive and interlaced video have been spliced together.

This category looks just like "mixed progressive and telecine", until you examine the 30000/1001 fps sections and see that they don't have the telecine pattern.

### How to encode each category

As I mentioned in the beginning, example MEncoder lines below are not meant to actually be used; they only demonstrate the minimum parameters to properly encode each category.

#### Progressive

Progressive video requires no special filtering to encode. The only parameter you need to be sure to use is `-ofps 24000/1001`. Otherwise, MEncoder will try to encode at 30000/1001 fps and will duplicate frames.

    mencoder dvd://1 -nosound -ovc lavc -ofps 24000/1001

It is often the case, however, that a video that looks progressive actually has very short parts of telecine mixed in. Unless you are sure, it is safest to treat the video as mixed progressive and telecine. The performance loss is small [3].

#### Telecined

Telecine can be reversed to retrieve the original 24000/1001 content, using a process called inverse-telecine. MPlayer contains several filters to accomplish this; the best filter, `pullup`, is described in the mixed progressive and telecine section.

#### Interlaced

For most practical cases it is not possible to retrieve a complete progressive video from interlaced content. The only way to do so without losing half of the vertical resolution is to double the framerate and try to "guess" what ought to make up the corresponding lines for each field (this has drawbacks - see method 3).

1. Encode the video in interlaced form. Normally, interlacing wreaks havoc with the encoder's ability to compress well, but libavcodec has two parameters specifically for dealing with storing interlaced video a bit better: `ildct` and `ilme`. Also, using `mbd=2` is strongly recommended [2] because it will encode macroblocks as non-interlaced in places where there is no motion. Note that `-ofps` is NOT needed here.

       mencoder dvd://1 -nosound -ovc lavc -lavcopts ildct:ilme:mbd=2

2. Use a deinterlacing filter before encoding. There are several of these filters available to choose from, each with its own advantages and disadvantages. Consult `mplayer -pphelp` to see what's available (grep for "deint"), and search the MPlayer mailing lists to find many discussions about the various filters. Again, the framerate is not changing, so no `-ofps`. Also, deinterlacing should be done after cropping [1] and before scaling.

       mencoder dvd://1 -nosound -vf pp=lb -ovc lavc

3. Unfortunately, this option is buggy with MEncoder; it ought to work well with MEncoder G2, but that isn't here yet. You might experience crahes. Anyway, the purpose of `-vf tfields` is to create a full frame out of each field, which makes the framerate 60000/1001. The advantage of this approach is that no data is ever lost; however, since each frame comes from only one field, the missing lines have to be interpolated somehow. There are no very good methods of generating the missing data, and so the result will look a bit similar to when using some deinterlacing filters. Generating the missing lines creates other issues, as well, simply because the amount of data doubles. So, higher encoding bitrates are required to maintain quality, and more CPU power is used for both encoding and decoding. tfields has several different options for how to create the missing lines of each frame. If you use this method, then Reference the manual, and chose whichever option looks best for your material. Note that when using `tfields` you have to specify both `-fps` and `-ofps` to be twice the framerate of your original source.

       mencoder dvd://1 -nosound -vf tfields=2 -ovc lavc -fps 60000/1001 -ofps 60000/1001

4. If you plan on downscaling dramatically, you can extract and encode only one of the two fields. Of course, you'll lose half the vertical resolution, but if you plan on downscaling to at most 1/2 of the original, the loss won't matter much. The result will be a progressive 30000/1001 frames per second file. The procedure is to use `-vf field`, then crop [1] and scale appropriately. Remember that you'll have to adjust the scale to compensate for the vertical resolution being halved.

       mencoder dvd://1 -nosound -vf field=0 -ovc lavc

#### Mixed progressive and telecine

In order to turn mixed progressive and telecine video into entirely progressive video, the telecined parts have to be inverse-telecined. There are three ways to accomplish this, described below. Note that you should always inverse-telecine before any rescaling; unless you really know what you're doing, inverse-telecine before cropping, too [1]. `-ofps 24000/1001` is needed here because the output video will be 24000/1001 frames per second.

- `-vf pullup` is designed to inverse-telecine telecined material while leaving progressive data alone. In order to work properly, `pullup` must be followed by the `softskip` filter or else MEncoder will crash. `pullup` is, however, the cleanest and most accurate method available for encoding both telecine and "mixed progressive and telecine".

      mencoder dvd://1 -nosound -vf pullup,softskip -ovc lavc -ofps 24000/1001

- An older method is to, rather than inverse-telecine the telecined parts, telecine the non-telecined parts and then inverse-telecine the whole video. Sound confusing? softpulldown is a filter that goes through a video and makes the entire file telecined. If we follow softpulldown with either `detc` or `ivtc`, the final result will be entirely progressive. `-ofps 24000/1001` is needed.

      mencoder dvd://1 -nosound -vf softpulldown,ivtc=1 -ovc lavc -ofps 24000/1001

- I haven't used `-vf filmdint` myself, but here's what D Richard Felker III has to say:

  > It's OK, but IMO it tries to deinterlace rather than doing inverse telecine too often (much like settop DVD players & progressive TVs) which gives ugly flickering and other artifacts. If you're going to use it, you at least need to spend some time tuning the options and watching the output first to make sure it's not messing up.

#### Mixed progressive and interlaced

There are two options for dealing with this category, each of which is a compromise. You should decide based on the duration/location of each type.

- Treat it as progressive. The interlaced parts will look interlaced, and some of the interlaced fields will have to be dropped, resulting in a bit of uneven jumpiness. You can use a postprocessing filter if you want to, but it may slightly degrade the progressive parts.

  This option should definitely not be used if you want to eventually display the video on an interlaced device (with a TV card, for example). If you have interlaced frames in a 24000/1001 frames per second video, they will be telecined along with the progressive frames. Half of the interlaced "frames" will be displayed for three fields' duration (3/(60000/1001) seconds), resulting in a flicking "jump back in time" effect that looks quite bad. If you even attempt this, you must use a deinterlacing filter like `lb` or `l5`.

  It may also be a bad idea for progressive display, too. It will drop pairs of consecutive interlaced fields, resulting in a discontinuity that can be more visible than with the second method, which shows some progressive frames twice. 30000/1001 frames per second interlaced video is already a bit choppy because it really should be shown at 60000/1001 fields per second, so the duplicate frames don't stand out as much.

  Either way, it's best to consider your content and how you intend to display it. If your video is 90% progressive and you never intend to show it on a TV, you should favor a progressive approach. If it's only half progressive, you probably want to encode it as if it's all interlaced.

- Treat it as interlaced. Some frames of the progressive parts will need to be duplicated, resulting in uneven jumpiness. Again, deinterlacing filters may slightly degrade the progressive parts.

### Footnotes

1. #### About cropping:

   Video data on DVDs are stored in a format called YUV 4:2:0. In YUV video, luma ("brightness") and chroma ("color") are stored separately. Because the human eye is somewhat less sensitive to color than it is to brightness, in a YUV 4:2:0 picture there is only one chroma pixel for every four luma pixels. In a progressive picture, each square of four luma pixels (two on each side) has one common chroma pixel. You must crop progressive YUV 4:2:0 to even resolutions, and use even offsets. For example, `crop=716:380:2:26` is OK but `crop=716:380:3:26` is not.

   When you are dealing with interlaced YUV 4:2:0, the situation is a bit more complicated. Instead of every four luma pixels in the frame sharing a chroma pixel, every four luma pixels in each field share a chroma pixel. When fields are interlaced to form a frame, each scanline is one pixel high. Now, instead of all four luma pixels being in a square, there are two pixels side-by-side, and the other two pixels are side-by-side two scanlines down. The two luma pixels in the intermediate scanline are from the other field, and so share a different chroma pixel with two luma pixels two scanlines away. All this confusion makes it necessary to have vertical crop dimensions and offsets be multiples of four. Horizontal can stay even.

   For telecined video, I recommend that cropping take place after inverse telecining. Once the video is progressive you only need to crop by even numbers. If you really want to gain the slight speedup that cropping first may offer, you must crop vertically by multiples of four or else the inverse-telecine filter won't have proper data.

   For interlaced (not telecined) video, you must always crop vertically by multiples of four unless you use `-vf field` before cropping.

2. #### About encoding parameters and quality:

   Just because I recommend `mbd=2` here doesn't mean it shouldn't be used elsewhere. Along with `trell`, `mbd=2` is one of the two libavcodec options that increases quality the most, and you should always use at least those two unless the drop in encoding speed is prohibitive (e.g. realtime encoding). There are many other options to libavcodec that increase encoding quality (and decrease encoding speed) but that is beyond the scope of this document.

3. #### About the performance of pullup:

   It is safe to use `pullup` (along with `softskip` ) on progressive video, and is usually a good idea unless the source has been definitively verified to be entirely progressive. The performace loss is small for most cases. On a bare-minimum encode, `pullup` causes MEncoder to be 50% slower. Adding sound processing and advanced `lavcopts` overshadows that difference, bringing the performance decrease of using `pullup` down to 2%.