[FFmpeg-devel] [PATCH] avformat/mpegts: initialize max_packet_size when sub-demuxer

Gyan Doshi ffmpeg at gyani.pro
Mon Feb 7 06:04:50 EET 2022



On 2022-02-07 03:59 am, Marton Balint wrote:
>
>
> On Sat, 5 Feb 2022, Gyan Doshi wrote:
>
>> bca30570d2 added a user option to set max_packet_size replacing
>> a hardcoded value. This had a side-effect of leaving the field
>> set to 0 when packet demuxing is carried out from another demuxer
>> using avpriv functions, which could lead to demux failure.
>>
>> Hardcoded max_packet_size inside avpriv_mpegts_parse_open to
>> 2048000 to avoid this. Value chosen to be 10x that of default value
>> to accommodate large payloads.
>
> I don't understand why the default is different from the normal mpegts 
> case. Large payloads can happen there as well, and previously it was 
> assumed that splitting is OK, because it will be parsed anyway.
The option was added because MPEG-TS allows any codec to be carried as a 
private stream and when demuxing that, the parser isn't inserted, even 
when forcing a decoder, hence the need to not have split packets. In 
this case, the user can't tune the value, so I went with an expansive one.

Regards,
Gyan


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