## 2.4 Encoding with MEncoder

For the complete list of available MEncoder options and examples, please see the man page.

### 2.4.1 Encoding 2 or 3-pass DivX4

2-pass encoding: 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 2-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.

This example shows how to encode a DVD to a 2-pass DivX4 AVI. Just two commands are needed:
`rm frameno.avi` - remove this file, which can come from a previous 3-pass encoding (it interferes with current one)
`mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1:more_options -oac copy -o movie.avi
mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2:more_options -oac copy -o movie.avi`

3-pass encoding: this is an extension of 2-pass encoding, where the audio encoding takes place in a separate pass. This method enables estimation of recommended video bitrate in order to fit on a CD. Also, the audio is encoded only once, unlike in 2-pass mode. The schematics:

1. Remove conflicting temporary file:

   `rm frameno.avi`

2. First pass:

   `mencoder <file/DVD> -ovc frameno -oac mp3lame -lameopts vbr=3:more_options -o frameno.avi`

   An audio-only avi file will be created, containing only the requested audio stream. Don't forget `-lameopts`, if you need to set it. If you were encoding a long movie, MEncoder prints the recommended bitrate values for 650Mb, 700Mb, and 800Mb destination sizes, after this pass finishes.

3. Second pass:

   `mencoder <file/DVD> -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vpass=1:vbitrate=<bitrate>`

   Alias the first pass of DivX4 video encoding. Optionally specify the video bitrate MEncoder printed at the end of the previous pass.

4. Third pass:

   `mencoder <file/DVD> -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vpass=2:vbitrate=<bitrate>`

   Alias the second pass of DivX4 video encoding. Optionally specify the video bitrate MEncoder printed at the end of the previous pass. In this pass, audio from `frameno.avi` will be inserted into the destination file.. and it's all ready!

#### Example for 3-pass encoding:

`rm frameno.avi` - remove this file, which can come from a previous 3-pass encoding (it interferes with current one)
`mencoder -dvd 2 -ovc frameno -o frameno.avi -oac mp3lame -lameopts vbr=3:more_options
mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1:more_options -oac copy -o movie.avi
mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2:more_options -oac copy -o movie.avi`

2 or 3-pass encoding using internal libavcodec controller: Optionally you can use libavcodec's internal 2 or 3-pass mode, it may give you better final rate accuracy than using the external, DivX4-inspired 2-pass rate controler with libavcodec.

- 2-pass encoding:
  `mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 (audio-options) -o movie.avi
  mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 (audio-options) -o movie.avi`
- 3-pass encoding:
  `rm -f frameno.avi
  mencoder -dvd 2 -ovc frameno (audio-options) -o frameno.avi
  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`

### 2.4.2 Rescaling movies

Often the need to resize movie images' size emerges. Its reasons can be many, examples are decreasing output file size, encoding SVCDs to DivX. Ripped DVDs are mostly rescaled, for example a 4:3 DVD should be 640x480, especially when you want it to fit to 1 CD, and have good quality at the same time. SVCDs have 480x480 size, and their header contains the aspect ratio the player should use (Ex.: 480x480 + 4:3 = 640x480). However when encoding to AVI (DivX) files, you have be aware that AVI headers don't store this value. Thus, the only solution is rescaling.

The scaling process is handled by the 'scale' video filter: `-vop scale=X:Y`. Its quality can be set with the `-sws` option. If it's not specified, MEncoder will use 0: fast bilinear.

Usage:
`mencoder sample-svcd.mpg -ovc lavc -lavcopts vcodec=mpeg4:more_options -vop scale=640:480 -oac copy -o output.avi`

### 2.4.3 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 MPEG1 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, Vorbis) and mux it into the output stream. Use the `-audiofile <filename>` option for this.

### 2.4.4 Fixing AVIs with broken index or interleaving

Easiest thing. We simply copy the video and audio streams, and MEncoder generates the index. Of course this cannot fix possible bugs in the video and/or audio streams. It also fixes files with broken interleaving, thus the `-ni` option won't be needed for them anymore.

Command: `mencoder -idx input.avi -ovc copy -oac copy -o output.avi`

### 2.4.5 Encoding with the libavcodec codec family

libavcodec provides simple encoding to a lot of interesting video and audio formats (currently its audio codecs are unsupported). You can encode to the following codecs:

- mjpeg - Motion JPEG
- h263 - H263
- h263p - H263 Plus
- mpeg4 - DivX4
- msmpeg4 - the old DivX
- msmpeg4v2 - Micro$oft MPEG4 V2 (DivX alias MP43 predecessor)
- rv10 - an old RealVideo codec
- mpeg1video - MPEG1 video :)

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`

### 2.4.6 Encoding from multiple input image files (JPEGs, PNGs or TGAs)

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...). Watch for the PNG decoder, as currently it can output only to RGB formats, thus can't be used with codecs that require YUV as input, like DivX4 or ffmpeg's msmpeg4.

#### Examples

The explanation of the `-mf` option can be found below in the global Options section and in the man page.

Creating a DivX4 file from all the JPEG files in the current dir:
`mencoder \*.jpg -mf on:w=800:h=600:fps=25 -ovc divx4 -oac copy -o output.avi`

Creating a DivX4 file from some JPEG files in the current dir:
`mencoder frame001.jpg,frame002.jpg -mf on:w=800:h=600:fps=25 -ovc divx4 -oac copy -o output.avi`

Creating a Motion JPEG (MJPEG) file from all the JPEG files in the current dir:
`mencoder \*.jpg -mf on:w=800:h=600:fps=25 -ovc copy -oac copy -o output.avi`

Creating an uncompressed file from all the PNG files in the current dir:
`mencoder \*.png -mf on:w=800:h=600:fps=25:type=png -ovc raw -oac copy -o output.avi`

Creating a Motion PNG (MPNG) file from all the PNG files in the current dir:
`mencoder \*.png -mf on: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 dir:
`mencoder \*.tga -mf on:w=800:h=600:fps=25:type=tga -ovc copy -oac copy -o output.avi`

### 2.4.7 Extracting DVD subtitles to a Vobsub file

MEncoder is capable of extracting subtitles from a DVD into Vobsub fomat 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.

#### Examples

Copying two subtitles from a DVD while doing 3-pass encoding
`rm subtitles.idx subtitles.sub`
`mencoder -dvd 1 -vobsubout subtitles -vobsuboutindex 0 -sid 2 -o frameno.avi -ovc frameno -oac mp3lame -lameopts vbr=3`
`mencoder -dvd 1 -oac copy -ovc divx4 -divx4opts pass=1`
`mencoder -dvd 1 -oac copy -ovc divx4 -divx4opts pass=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`