Re: [FFmpeg-devel] [PATCH] avformat/mxfdec: support MCA audio information

[Pierre-Anthony Lemieux <pal@sandflow.com>]

On Sun, Jan 2, 2022 at 11:13 PM Andreas Rheinhardt
<andreas.rheinhardt@outlook.com> wrote:
>
> Pierre-Anthony Lemieux:
> > On Sat, Jan 1, 2022 at 5:35 PM Andreas Rheinhardt
> > <andreas.rheinhardt@outlook.com> wrote:
> >>
> >> Pierre-Anthony Lemieux:
> >>> Minor suggestion below.
> >>>
> >>> In addition, will sample file(s) be added to FATE? Below are two examples:
> >>>
> >>> http://ffmpeg-imf-samples-public.s3.us-west-1.amazonaws.com/callout_51_l_r_c_lfe_ls_rs.mxf
> >>> http://ffmpeg-imf-samples-public.s3.us-west-1.amazonaws.com/callout_51_l_c_r_ls_rs_lfe.mxf
> >>>
> >>
> >> These files are 1.62MiB each, having 49 packets of lossless audio. Would
> >> it decrease coverage if this were reduced? After all, the amount of
> >> audio should not matter for channel reorderings.
> >
> > Each channel contains a synthesized human voice that announces the
> > name of the channel, so that a reviewer can, by simple inspection,
> > confirm the expected channel order. This will be particularly useful
> > when automatic channel reordering is performed.
> >
> > The contents of each channel could be changed to a single tone with
> > each channel assigned a different tone, e.g. 1 to 6 kHz. This might
> > make the files shorter.
> >
>
> A human voice sounds like something that is nice to have; but does it
> have to be 24bit? As I see it, mxf allows 16bit sound everywhere where
> it allows 24bit.

I have never seen or created an MXF file that uses MCA and that has
16-bit PCM. I do not recommend treading new ground.

> Furthermore, the channels will still be recognizably
> different if the audio is cut off at 1s (this will cut off the "effect"
> from "low frequency effect" and will also cut off beeps for the others).

Ok. See:

http://ffmpeg-imf-samples-public.s3-website-us-west-1.amazonaws.com/callout_51_l_c_r_ls_rs_lfe.v2.mxf
http://ffmpeg-imf-samples-public.s3-website-us-west-1.amazonaws.com/callout_51_l_r_c_lfe_ls_rs.v2.mxf

>
> - Andreas
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