6.1. Selecting codecs and container formats
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## 6.1. Selecting codecs and container formats

Audio and video codecs for encoding are selected with the `-oac` and `-ovc` options, respectively. Type for instance:

    mencoder -ovc help

to list all video codecs supported by the version of MEncoder on your machine. The following choices are available:

Audio Codecs:

Audio codec name | Description
--- | ---
mp3lame | encode to VBR, ABR or CBR MP3 with LAME
lavc | use one of `libavcodec`'s audio codecs
faac | FAAC AAC audio encoder
toolame | MPEG Audio Layer 2 encoder
twolame | MPEG Audio Layer 2 encoder based on tooLAME
pcm | uncompressed PCM audio
copy | do not reencode, just copy compressed frames

Video codecs:

Video codec name | Description
--- | ---
lavc | use one of `libavcodec`'s video codecs
xvid | Xvid, MPEG-4 Advanced Simple Profile (ASP) codec
x264 | x264, MPEG-4 Advanced Video Coding (AVC), AKA H.264 codec
nuv | nuppel video, used by some realtime applications
raw | uncompressed video frames
copy | do not reencode, just copy compressed frames
frameno | used for 3-pass encoding (not recommended)

Output container formats are selected with the `-of` option. Type:

    mencoder -of help

to list all containers supported by the version of MEncoder on your machine. The following choices are available:

Container formats:

Container format name | Description
--- | ---
lavf | one of the containers supported by `libavformat`
avi | Audio-Video Interleaved
mpeg | MPEG-1 and MPEG-2 PS
rawvideo | raw video stream (no muxing - one video stream only)
rawaudio | raw audio stream (no muxing - one audio stream only)

The AVI container is the native container format for MEncoder, which means that it's the one that is best handled, and the one for which MEncoder was designed. As noted above, other container formats are usable, but you may experience problems when using them.

`libavformat` containers:

If you selected `libavformat` to do the muxing of the output file (by using the `-of lavf`), the appropriate container format will be determined by the file extension of the output file. You may force a particular container format with `libavformat`'s `format` option.

`libavformat` container name | Description
--- | ---
mpg | MPEG-1 and MPEG-2 PS
asf | Advanced Streaming Format
avi | Audio-Video Interleaved
wav | Waveform Audio
swf | Macromedia Flash
flv | Macromedia Flash video
rm | RealMedia
au | SUN AU
nut | NUT open container (experimental and not yet spec-compliant)
mov | QuickTime
mp4 | MPEG-4 format
dv | Sony Digital Video container
mkv | Matroska open audio/video container

As you can see, `libavformat` allows MEncoder to mux into a considerable variety of containers. Unfortunately, as MEncoder was not designed from the beginning to support container formats other than AVI, your should really be paranoid about the resulting file. Please check to be sure that the audio/video synchronization is OK and that the file can be played correctly by players other than MPlayer.

Example 6.1. encode to Macromedia Flash format

Creating a Macromedia Flash video suitable for playback in a web browser with the Macromedia Flash plugin:

    mencoder input.avi -o output.flv -of lavf \
        -oac mp3lame -lameopts abr:br=56 -srate 22050 -ovc lavc \
        -lavcopts vcodec=flv:vbitrate=500:mbd=2:mv0:trell:v4mv:cbp:last_pred=3

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