GetChannel

GetChannel(clip clip, int ch1 [, int ch2, ...] )
GetChannels(clip clip, int ch1 [, int ch2, ...] )
GetLeftChannel(clip clip)
GetRightChannel(clip clip)

• GetChannel returns one or more channels of a multichannel signal.
• GetLeftChannel returns the left channel from a stereo signal, and GetRightChannel returns the right.
• GetChannels is an alias for GetChannel and can be used interchangeably.

The ordering of the channels is determined by the ordering of the input file, because AviSynth doesn't assume any ordering (see Remarks).

In case of WAV files, the ordering should be as follows:

WAV, 2 channels (stereo)
1	left channel
2	right channel

WAV, 5.1 channels
2	front right channel
3	front center channel
4	LFE (Low Frequency Enhancement; Subwoofer)
5	rear left channel
6	rear right channel

Examples

• Removes right channel information, and return as mono clip with only left channel:

video = AviSource("c:\filename.avi")
stereo = WavSource("c:\afx-ab3_t4.wav")
mono = GetLeftChannel(stereo)
return AudioDub(video, mono)

• Do the same, alternate syntax:

video = AviSource("c:\filename.avi")
stereo = WavSource("c:\afx-ab3_t4.wav")
mono = GetChannel(stereo, 1)
return AudioDub(video, mono)

• You could also obtain the channels from the AVI file itself:

video = AviSource("c:\filename.avi")
return GetChannel(video, 1)

• Converts AVI with 5.1 audio to a stereo signal

(But see below for channel ordering, and here for more complex downmix functions.)

video = AviSource("c:\divx_51.avi")
stereo = GetChannel(video, 1, 2)
return AudioDub(video, stereo)

• Converts AVI with "uncompressed 5.1 wav" audio to a stereo signal:

video = AviSource("c:\divx_wav.avi")
audio = WavSource("c:\divx_wav.avi")
stereo = GetChannel(audio, 1, 2)
return AudioDub(video, stereo)

Remarks

Every file format has a different internal channel ordering. The following table gives this internal ordering for some formats (useful for plugin writers), but it is the decoder's task to return the expected (WAV) channel order. If you use decoders like NicAudio/BassAudio or ffdshow/AC3_filter you don't need to worry about this.

Format	Channel 1	Channel 2	Channel 3	Channel 4	Channel 5	Channel 6
5.1 WAV	front left channel	front right channel	front center channel	LFE	rear left channel	rear right channel
5.1 AC3	front left channel	front center channel	front right channel	rear left channel	rear right channel	LFE
5.1 DTS	front center channel	front left channel	front right channel	rear left channel	rear right channel	LFE
5.1 AAC	front center channel	front left channel	front right channel	rear left channel	rear right channel	LFE
5.1 AIFF	front left channel	rear left channel	front center channel	front right channel	rear right channel	LFE
5.1 FLAC	front left channel	front right channel	front center channel	LFE	rear left channel	rear right channel
5.1 WMA	front left channel	front right channel	front center channel	LFE	rear left channel	rear right channel

• 5.1 DTS: the LFE is on a separate stream (much like on multichannel MPEG2).
• A free version of the AAC specifications are unavailable online.