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

[Gijs Peskens <gijs@peskens.net>]

On 11-11-2022 16:05, Nomis101 wrote:
> Am 11.11.22 um 14:48 schrieb Nomis101:
>> Am 11.11.22 um 14:05 schrieb Jan Ekström:
>>> On Wed, Nov 9, 2022 at 9:15 PM Nomis101 <Nomis101@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@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@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
>>
>> OK, thanks Jan for the detailed explanation. I will check D company. 
>> Infuse has implemented it independently of FFmpeg.  VLC and Mediainfo 
>> I do not know. The specs were mentioned in the bug, but also FFmpeg. 
>> But both would not implement anything if there was no specification 
>> for it.
>
>
> There is also support in "dlb_mp4base":
> https://github.com/DolbyLaboratories/dlb_mp4base/blob/8da6d4a8fc095a88349fbdac33e7e68fb3b93649/src/mp4_muxer.c#L149 
>
>
But does it correctly demux a variety of files generated by FFMPEG?
>>
>>
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