[FFmpeg-user] stereo upmix and matrix_encoding

[Paul B Mahol]

On Fri, Jun 16, 2023 at 2:46 PM Martin Thomas Schrott <list at mtsonline.at>
wrote:

> ok got it. :-)
>
> had to add -ac 6 before surround  otherwise it would output a stereo
> stream.
>
>
>
That should not be needed at all.

But only logs would show what really happens.

Capturing logs should not be hard at all.

If you use windows only send screenshots instead....


> thanks!
>
> Martin
>
>
>
> Am 16.06.2023 um 13:51 schrieb Martin Thomas Schrott:
> > Hi folgs,
> >
> >
> > I would like to upmix a stereo file to a surround one and came accross
> > the "surround" filter in ffmpeg documentation. Seems this does what I
> > would like to do, but I could not find how to use it correctly as it
> > seems.
> >
> >
> > I would like to combine it with aresample=matrix_encoding=dplii to get
> > a correct surround wav out.
> >
> >
> > So I tried to use a -filter_complex with my stereo as an input file.
> >
> > And send the output from surround to aresample for encoding.
> >
> >
> > -i myfile.wav -filter_complex "[0:a]surround[a1];
> > [a1]aresample=matrix_encoding=dplii" outfile.wav
> >
> >
> > The file still is normal stereo and ignored by decoders. :-(
> >
> > I also tried to add ichl=5.1 to the aresample - which also did not help.
> >
> >
> > Could anyone please either tell me, what I am doing wrong,
> >
> > or give me another working way to upmix the file and encode it correctly?
> >
> >
> > (I know this way the phaseshift is missing - so if someone could
> > include that too, I would appreciate that of course) ;-)
> >
> >
> > If combining does not work properly I also would be fine with
> > outputing a six channel wav or six separate wave files, as I have the
> > code to encode this correctly. :-)
> >
> >
> > Thanks for any hint and help!
> >
> >
> > cheers
> >
> > Martin
> >
> >
> >
> >
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