[FFmpeg-devel] [RFC] Private streams in MPEG PS

Baptiste Coudurier baptiste.coudurier
Wed May 27 20:22:51 CEST 2009


On 5/27/2009 11:00 AM, Jai Menon wrote:
> Hi,
> I'm becoming increasingly suspicious of this check in lavf/mpeg.c:370 -
>   4093        mru     if (startcode == PRIVATE_STREAM_1 &&
> !m->psm_es_type[startcode & 0xff]) {
>              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Looking at issue 1122 and 725 on roundup,  I'm inclined to believe
> that a lot of files out there don't have a program stream map (which I
> didn't back when issue 725 was reported). Removing this check actually
> would solve both 1122 and 725 without the need for the fix commited in
> r17150.

Humm, pes_es_type should be init to 0 anyway, if file have no program
stream map. Isn't the problem that psm_es_type is wrongly set ?

> A related question is how we would handle two streams with the same
> startcode, one of which is a private substream, because the lavf
> stream id is set to the startcode value and is expected to be unique.
> Is such a situation impossible? If it isn't should the startcode for
> the private substream be conactenated with 0x1bd to produce a unique
> id?

Well, there should be a way to differentiate them in this case, and the
substarcode mechanism seems the most used around.


Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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