[FFmpeg-user] 7.1 wave filter complex amerge issue

Paul B Mahol onemda at gmail.com
Sun Jan 24 12:44:50 EET 2021


On Sun, Jan 24, 2021 at 11:39 AM Bouke <bouke at editb.nl> wrote:

>
>
> > On 24 Jan 2021, at 11:29, Paul B Mahol <onemda at gmail.com> wrote:
> >
> > On Sun, Jan 24, 2021 at 11:26 AM Bouke <bouke at editb.nl <mailto:
> bouke at editb.nl>> wrote:
> >
> >> Trying to remap channels in a 7.1 Wave file, but that gives me a strange
> >> error.
> >>
> >> (I’ve reduced my lines to the most simple to reproduce.)
> >>
> >> When I use the same input file, but do a 5.1 remap it works as expected:
> >> /Applications/ffmpeg -i /Volumes/Data/LC_testfiles/8chan.wav
> >> -filter_complex
> >>
> "[0:0][0:0][0:0][0:0][0:0][0:0]amerge=inputs=6,pan=5.1|c0=c0|c1=c1|c2=c2|c3=c3|c4=c4|c5=c5|[mix]"
> >> -map "[mix]" -f null -
> >>
> >> BUT, with 7.1 it fails
> >> /Applications/ffmpeg -i /Volumes/Data/LC_testfiles/8chan.wav
> >> -filter_complex
> >>
> "[0:0][0:0][0:0][0:0][0:0][0:0][0:0][0:0]amerge=inputs=8,pan=7.1|c0=c0|c1=c1|c2=c2|c3=c3|c4=c4|c5=c5|c6=c6|c7=c7|[mix]"
> >> -map "[mix]" -f null -
> >>
> >> Is it me, or is this a bug?
> >>
> >> Bouke
> >>
> >>
> >
> > I thought you gonna amerge mono channels into 7.1, but you use already
> 7.1
> > input.
> >
>
> Yes, I know. This is the simplest way of showing that there is something
> strange going on.
> The aim is to do a channel remap to get a correct channel layout for the
> R128 filter for eg
> So the mapping can be different, and could be something like:
> -filter_complex
> "[0:0][0:0][0:0][0:0][0:0][0:0][0:0][0:0]amerge=inputs=8,pan=7.1|c0=c0|c1=c2|c2=c1|c3=c4|c4=c5|c5=c6|c6=c7|c7=c3|[mix];[mix]ebur128=peak=true"
> -f null -
>

amerge filter merges channels, so if inputs have 8 channels each, output
will have 64 channels.
I think the limitation is there because channels layouts have support for
limited number of channels, and 64 channels are definitely not supported by
some filters because libswresample will not convert to different sample
format because of unknown layout of 64 channels input.


>
> Bouke
>
> >
> >> Failed to inject frame into filter network: Invalid argument
> >> Error while processing the decoded data for stream #0:0
> >> Conversion failed!
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