[FFmpeg-devel] [PATCH] avformat/movenc: Remove experimental status of TrueHD-in-MP4 muxing (mlpa)

[Jan Ekström]

On Wed, Nov 9, 2022 at 9:15 PM Nomis101 <Nomis101 at web.de> wrote:
>
> Am 06.11.22 um 21:57 schrieb Carl Eugen Hoyos:
> > Am Sa., 5. Nov. 2022 um 22:31 Uhr schrieb Nomis101 <Nomis101 at web.de>:
> >>
> >> Support for mlpa muxing was added back in 2019:
> >> http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=808a6717e0c584738c60a109afd6d47f4973d619
> >> But it was hidden back then behind FF_COMPLIANCE_EXPERIMENTAL, because it was new and there was no
> >> support from other applications.
> >>
> >> In the meantime there is support in MediaInfo: MediaArea/MediaInfoLib#1258
> >> For VLC: videolan/vlc at 9c49f40
> >> Since version 7.3.4 for Infuse: https://community.firecore.com/t/dolby-mlp-mlpa-codec-support/26100/31
> >> And mpv does support this as well.
> >
> > If there was ever a good reason to make this feature experimental,
> > I don't think these applications change the situation.
>
>
> The reason to make this experimental was, because there was no implementation from others at this time.
> http://ffmpeg.org/pipermail/ffmpeg-devel/2019-August/248435.html
> Now, there is implementation from others. How many implementation from others will be needed to
> change the situation?
>

I think the main thing was to have the feature verified by non-FFmpeg
things. Basically, if you wrote out a TrueHD file and actual 3rd party
implementations that didn't just utilize FFmpeg for reading would
happily read it, then the flag should be removed.

If the VLC commit did not specifically say "we did it like this to
enable support for files that FFmpeg generated" but rather that they
followed the spec, then that's one alternative implementation indeed.
And if MediaInfo or that Infuse thing also added support for the exact
same mapping and that neither specifically utilized FFmpeg internally,
then those also apply.

Finally, I think the D company has a git repo for "dlb_mp4base", you
could check if that supports this mapping.

Best regards,
Jan