[Ffmpeg-devel] [Ffmpeg-devel-old] Re: avi out is buggy

[Måns Rullgård]

Erik Slagter <erik at slagter.name> writes:

> On Mon, 2005-05-09 at 14:56 +0200, M?ns Rullg?rd wrote:
>> ISO 13818 does not mention AC3, so AC3 in an MPEG stream is not
>> compliant with that standard.  The DVD spec specifies one way of
>> storing AC3 in MPEG-PS.  ATSC A/52 specifies an extension to the
>> MPEG-TS format, allowing for AC3 audio.  Other schemes for AC3 in MPEG
>> exists, but are less widely used.
>
> Do you know why to choose to multiplex the private1_stream and didn't
> use their own private stream?

private_stream_1 is a good choice, since it has the full PES header,
with PTS and whatnot.  The other option would be to use
private_stream_2, and define some new syntax for timestamps.
Borrowing one of the "reserved" values would make the stream
non-compliant.  These values are intended for use by future versions
of the standard.

To clarify what I said earlier, AC3 audio in private_stream_1 is
compliant with the standard, since it does not place any restrictions
on the contents of the private streams.  However, to actually access
the AC3 data, one must make assumptions outside the ISO standard.
IMHO, it's perfectly fine to define compatible extensions to a
standard in this manner.

-- 
M?ns Rullg?rd
mru at inprovide.com