[speex-dev] Re: Speex, what container?

ChristianHJW christian at matroska.org
Sat Mar 6 03:06:22 PST 2004

miguel.gomes wrote:
> But is there any sound player for windows that plays speex in an ogg container?

If the ACM codec is installed, DirectShow can use the ACM codec for 
decoding, but somebody had to patch Tobias' OggDS DirectShow filters to 
call the corresponding wFormat tag of the Speex ACM codec if a Speex 
track is found in the Ogg files.

To create the Ogg's with DirectShow, you could use Tobias' Ogg muxer 
filter also, but it also needed to be patched. Funny enough, your app 
could use the Ogg muxer filter and the ACM codec to produce an Ogg with 
speex content, but this would then not be a valid Ogg Speex track, but 
an OGM track containing a WAV audio track ( like MP3 in OGM ).

To produce a valid Ogg Speex track, the Ogg muxer had to be patched at 
least, but better even a DShow Speex encoder filter should be written, 
similar to the Vorbis encoder filter that Tobias has done. The encoder 
and the muxer have their own MEDIASUBTYPE on DirectShow, so the muxer 
knows this is native Vorbis packets coming in and no WAV audio, thus it 
can write real Ogg Vorbis tracks when the DShow encoder filter is being 
used. For the same reason, a real Speex decoder filter could be useful.

matroska project admin

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