[matroska-devel] Audio ACM compatibility

Steve Lhomme steve.lhomme at free.fr
Tue Feb 18 13:59:00 CET 2003

 <ChrHJW_work> no MS compatibility mode for audio guys !
 <myFUN> but ...
 <BlackSun> or wFormatTag
 <ChrHJW_work> but ?
 <ChrHJW_work> Cyrius, misunderstanding ?
 <ChrHJW_work> the plan for audio is to use native matroska IDs from the start
 <ChrHJW_work> A_MPEGLAYER3 for Mp3
 <ChrHJW_work> A_DOL_AC3 for AC3
 <ChrHJW_work> A_VORBIS for Vorbis
 <myFUN> for usage of exsiting filters the parser needs the wFormatTag or GUID
 <ChrHJW_work> yes Jan, here is how we do it until we dont have UCI plugins :
 <myFUN> that means i must hardcode a list into the parser for mapping those
strings to GUIDs
 <ChrHJW_work> we will backup the WAVEFORMATEX structure in KaxCodecPrivateData
[13:22] * BlackSun put his nose in the story
 <myFUN> ok
 <BlackSun> but the DSF need to provide a wFormatTag or a GUID
 <ChrHJW_work> not for the time being, as we can be sure all file creation apps
will have this backup of WAVEFORMATEX

2 reasons why it's not good :
- we will never know all the existing ACM codec. So one way or another we'll
have to support WAVEFORMATEX someday
- putting WAVEFORMATEX in KaxCodecPrivate is very bad, because some (most)
(native) codec don't require it, and encoding apps will have to create one anyway...

Remember we're not building smething for a demo and change everything after !!!
We're building something that is going to last. So please stop doing this kind
of ugly hack !

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