[FFmpeg-devel] [PATCH] read header in FLAC demuxer

Justin Ruggles justin.ruggles
Sat Jan 31 16:47:53 CET 2009

M?ns Rullg?rd wrote:
> Justin Ruggles <justin.ruggles at gmail.com> writes:
>> M?ns Rullg?rd wrote:
>>> Michael Niedermayer <michaelni at gmx.at> writes:
>>>> On Fri, Jan 30, 2009 at 10:36:10PM -0500, Justin Ruggles wrote:
>>>>> Hi,
>>>>> Here is a patch to read the header in the raw FLAC demuxer.  Currently
>>>>> the header is passed through in the output AVPackets, which is not good
>>>>> and requires some ugliness on the decoder side.  After this patch is
>>>>> applied, the decoder can be changed so it doesn't have to handle the
>>>>> header except in the extradata.  The extradata handling in the decoder
>>>>> will also be simplified.
>>>> is it allowed to place the header in the stream instead of extradata in
>>>> flac in avi?
>>> If it is physically possible, someone will do it.
>> Should we really support everything that is physically possible?
> Of course not.
>> FLAC in avi and wav should not have the header in the stream.
> Flac in avi and wav simply shouldn't IMO.  In fact, avi shouldn't at
> all, and wav is only useful for PCM.
>>>> flac in mkv?
>>> No.
>>>> flac in * ?
>>> There's always Ogg...
>> Ogg doesn't use the raw FLAC header. It splits it up in its own funny
>> way, which we already support.
>> Do we have any other format that is header+frames that we allow the
>> header to be in the stream?
> It's possible to do all sorts of funny things with MPEG-PS/TS.  Some
> variants of AAC encapsulation put (parts of) the header outside the
> main stream, some put it all inline.

But raw FLAC doesn't do any funny things... There is a header, which
contains metadata, information about the stream, seek table, etc... It
is always completely separate from the audio frames.  If we only handle
it in the parser or decoder, we lose the ability to use that information
in the demuxer, right?


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