[vorbis-dev] Re: Re: New Ogg/Vorbis/Speex Directshow filters preview...

[Paul Bryson]

Andre Pang wrote...
> 2.  The source filter that we are referring to only concerns the Ogg
> filter: unlike many other filters, we have separate filters for the Ogg
> demuxer and the Vorbis decoder.  This is a more extensible and better
> design than putting everything in the one filter: it makes it far
> easier to support any future codecs that xiph.org bring out.  e.g.
> Putting in support for Ogg FLAC will be trivial compared to extending
> one monolithic Ogg filter.

I agree and I believe it was one of the greatest shortcomings of the OGM filters
designed by Tobias.

> > We could have used your Speex decoder filter to play Speex from
> > matroska container, but right now its unusable for us as it is.
>
> As I mentioned above, one of the ideas of the design of illiminable's
> filters is to be able to play Speex no matter what file it is contained
> in -- if you are having trouble playing Speex in Matroska, please send
> him (or myself) feedback, so that we can work things out.

I was unaware any tools that will place Speex in Matroska.  AFAIK, this is a
limitation of not having a tool to place Speex in Matroska, as well as there
being no GUIDs in the Matroska DirectShow playback filter to know what type of
pin to create.

> (I should
> also point out that the behaviour you want would be much harder to
> obtain from the filters hosted at CoreCodec.org, due to their tighter
> coupling with Ogg.)

I don't really understand this statement.  CoreVorbis is NOT a source filter and
cannot parse Ogg.  I will only decode the raw Vorbis packets handed to it from
whatever source filter.  In theory you should be able to connect the Illiminable
Ogg source filter directly to the CoreVorbis filter to decode Vorbis in Ogg.  Of
course this will not work at the moment because they are not using the same
GUIDs.

Perhaps there could be a problem in that the three packets used to initialize a
Vorbis stream are stored in the codec initialization area of Matroska so I don't
know exactly how they are handled by the CoreVorbis filter.  I am sure though
that a CoreCodec team member could answer this though.

As a side note, I don't believe its a bad thing that there is more than one
Vorbis DirectShow filter.  Choice is a good thing.  I know of no drawbacks with
the current CoreVorbis filter, but if you can make a better one, kudos.  One
thing is to make sure to get channel mappings correct for 5.1 channel streams.
There are some tools out there that will make files with the wrong channel
mappings.  And if nothing else, we really do need a new Ogg source filter that
is currently being developed.

<p>Pamel

<p><p>--- >8 ----
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