[FFmpeg-user] audio channel manipulation

[andrei ka]

interesting, looks like ffv1 did zero compression here, stream size of .mov
& ffv1 avi is the same. or the file size changed, it's only mediainfo
computed decompressed stream size ?


On Mon, Jan 21, 2019 at 10:11 PM Jim Shupert <jshupert at theppsgroup.com>
wrote:

> On 1/21/2019 2:45 PM, Moritz Barsnick wrote:
> > On Mon, Jan 21, 2019 at 14:01:52 -0500, Jim Shupert wrote:
> >> if it is in 4 streams you can pick which to hear.
> >>
> >> My capture system captures 10bit unc mov video [0:0]  ( 4ch_test.mov )
> >> and the 4 audio "tracks" are found in 1 stream as 4 channels [0:1.0 ,
> >> 0:1.1, 0:1.2, 0:1.3 ]
> > [...]
> >
> > Do you need the intermediate file 4s_b.avi? (I assume so, but your
> > final file 4s_b.mp4 can be created in one step, if that is desired.)
>
> Yes - both the ffv1 avi [ 4s_b.avi ] & the mp4 are the goal , the need.
> the original   capture mov [ 4ch_test.mov ]  is very simply what I am
> "able" to make via my hardware
> which is a blackmagic card running media express. That is I can capture
> all 4 "tracks"  but only & always into 1 stream with 4 channels
> >
> >> ---------------------------:: make the ffv1 avi from the 10b mov
> capture .
> >> 4s_b.avi
> >>
> >> ffmpeg -i 4ch_test.mov -vcodec ffv1 -level 3 -coder 1 -pix_fmt
> >> yuv422p10le -aspect 4:3 -g 1 \
> >>    -filter_complex "[0:a]pan=mono|c0=c0[a0]; [0:a]pan=mono|c0=c1[a1];
> >> [0:a]pan=mono|c0=c2[a2]; [0:a]pan=mono|c0=c3[a3]" \
> >>    -map 0:v -map "[a0]" -map "[a1]" -map "[a2]" -map "[a3]" -map 0:d -c
> >> copy -c:a pcm_s24le -f avi 4s_b.avi
> > Your filter
> >    "[0:a]pan=mono|c0=c0[a0]; [0:a]pan=mono|c0=c1[a1];
> [0:a]pan=mono|c0=c2[a2]; [0:a]pan=mono|c0=c3[a3]"
> > is indeed a neat trick to separate your channels into streams. There's
> > an easier way though: The "channelsplit" filter:
> > https://ffmpeg.org/ffmpeg-filters.html#channelsplit
> >
> > The second filter ("[0:1] [0:2] amerge") is just fine for creating
> > stereo from two separate channels.
>
> ahhhh :: an   "an easier way"   wonderful -- in truth I often find there
> are many "ways" ... i tend to keep using "one" after I find it works.
> Thank you...expanding my understanding is what i am after
> >
> >> https://trac.ffmpeg.org/wiki/AudioChannelManipulation
> > Apparently, you read the section "stereo → 2 × mono files". My
> > suggestion with the "channelsplit" is right below, in the section
> > "stereo → 2 × mono streams". Actually, both filters will work either
> > way, the examples are quite arbitrary, come to think of it.
> >
>
>
> will do -- thanks again
>
> and-- if anyone else has anyThing else to offer ... i am still anxious
> to learn more
> :)
>
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