[FFmpeg-devel] [PATCH] ffmpeg: add -map_channel option.

Michael Niedermayer michaelni at gmx.at
Tue Oct 25 14:25:53 CEST 2011


On Tue, Oct 25, 2011 at 11:07:53AM +0200, Clément Bœsch wrote:
> On Mon, Oct 24, 2011 at 06:29:10PM +0200, Michael Niedermayer wrote:
> > On Mon, Oct 24, 2011 at 04:19:10PM +0200, Michael Niedermayer wrote:
> > > On Mon, Oct 24, 2011 at 02:05:55PM +0200, Clément Bœsch wrote:
> > > > On Wed, Oct 19, 2011 at 11:42:15PM +0200, Michael Niedermayer wrote:
> [...]
> > > > > also shouldnt rematrix be independant of the existence of a channel_map
> > > > > 
> > > > 
> > > > Well, AFAIU, the rematrix is meant to automatically set the audio gain
> > > > levels for each channel; the channel mapping is "incompatible" with this,
> > > > it's all about reordering, or maybe with another phrasing: ppl won't
> > > > expect the levels to change (the number of output channels being fixed by
> > > > the number of -map_channel and not a specific -ac option)
> > > 
> > > if your inputs represents 5.1 and your output represenst 7.0 you need
> > > the rematrix code
> > 
> > a better and simpler example is stereo input and mono output
> > 
> 
> In case of stereo → mono with map_channel, you're likely to have something
> like:
>     ffmpeg -i stereo.wav -map_channel 0.0.0 left.wav -map_channel 0.0.1 right.wav

i meant that we have 2 input files, one with right and one with
left chanel and want one mono output file.

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Let us carefully observe those good qualities wherein our enemies excel us
and endeavor to excel them, by avoiding what is faulty, and imitating what
is excellent in them. -- Plutarch
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