[FFmpeg-devel] [PATCH] Add a parser for DNET (byte-swapped AC3).

Måns Rullgård mans
Wed Mar 2 23:18:04 CET 2011

Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:

> On Wed, Mar 02, 2011 at 09:10:21PM +0000, M?ns Rullg?rd wrote:
>> Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
>> >> Then how did you intend to detect it as ac3 in the first place?
>> >
>> > By the fact that the RealMedia header says "DNET"?
>> AC3 exists outside of realmedia file, you know...
> So what? Has anyone seen the byte-swapped variant outside a container?
> Either way libavformat has a better infrastructure to do this kind
> of format detection when it's hard to decide, a parser is not really
> such a great place for it.

The parser can reasonably assume it is being fed AC3 data in some form
or other, so the difficulty of detection is irrelevant there.

> Which, as said, is in addition to the fact whether there is a point
> at all of supporting byte-swapped raw AC3. It obviously exists
> in other containers, but already for that there seem to be no samples
> available, DNET is the only one actually common (and even that seems
> relative).

AC3 in WAV is fairly common.  I'm sure we have a few samples of that.

All else aside, calling it DNET is ridiculous.  It is called AC3
whatever container you wrap it in.  We don't have a CODEC_ID_ for every
tag used in some obscure container, we have one per codec.  Please keep
it that way.

M?ns Rullg?rd
mans at mansr.com

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