[FFmpeg-devel] [PATCH 4/4] avcodec/mpeg12enc: Deprecate using MPEG-2 intra VLC table for mpeg1video

Andreas Rheinhardt andreas.rheinhardt at gmail.com
Wed Nov 25 02:01:44 EET 2020


Marton Balint:
> 
> 
> On Tue, 24 Nov 2020, James Almer wrote:
> 
>> On 11/24/2020 11:41 AM, Andreas Rheinhardt wrote:
>>> This option just creates broken output because an MPEG-1 bitstream
>>> can't signal whether MPEG-2 intra VLC tables have been used.
> 
> If the output was really broken with this option then IMHO the
> deprecation is not really necessary here, and you can simply remove the
> option.
> 
It is spec-incompliant (mpeg1 does not allow mpeg2 tables and therefore
an mpeg1 bitstream has no field to signal which tables to use) and
undecodable by a spec-compliant decoder. One could write a decoder that
decodes it (namely one that uses the mpeg2-tables automatically), but I
am not aware of such a decoder existing.
I am not against just removing the option now. What do others think
about this?

- Andreas


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