Brian Cameron wrote: >> Need to do a correction for my last post about transcoding of Coherence. >> Coherence doesn't depend on the FFmpeg plugins of GStreamer. The current >> Coherence code implements mp4 transcoder, which depends on the qtdemux >> element of gst-plugins-good and h264parse/mp4mux elements of >> gst-plugins-bad 0.10.10. The GStremaer pipeline looks like "$file ! >> qtdemux name=d ! queue ! h264parse ! mp4mux name=mux d. ! queue ! mux.". >> As we can see, coherence doesn't do decoding/encoding, demux/mux are >> involved. >> >> For audio transcoding, the GStreamer lame element was used. But all the >> audio transcoding part is disabled in the current code. I've sent email >> to the upstream community for further information. > > I assume that lame is used for MP3 encoding. Obviously Solaris does > not provide any MP3 encoding support, and Fluendo does not yet sell any > MP3 encoder. Therefore, I think any such support would be disabled in > Solaris by default. One reason it might be disabled in the coherence > code is due to the fact that MP3 encoding is a non-free codec. > > Is it possible to configure coherence audio encoding to use a free > format that is supported on Solaris, such as ogg-vorbis. This might > not be useful for all users, but I'd think that coherence should provide > the option to encode audio in a free format. Just got the response from Coherence author. The MP3 encoding part is only needed for XBox experiment and it's a quick hack. The coherence community will "sort out the proper elements to use in advance and enable/disable transcoding pipelines accordingly". As for OpenSolaris, we can always disable the unsupported transcoding pipelines.
The proposal to use the free ogg vorbis/theora format has been sent out. As Mozilla community investigates big efforts on the open audio/video which makes use of ogg format for its HTML5 audio/video tag support, the ogg format is quite promising. It'll be good that coherence can support this option. >> Is it possible that Fluendo could provide similar codecs as h264parse >> (Parses raw h264 stream)/mp4mux (should be the part to mux the mp4 >> audio/video) do? Are there any replacement for them? > > We first should discuss this with the GStreamer community to find out > if these plugins can be migrated to gst-plugins-good. That would be > the normal process for getting new plugins integrated. We could > consider patching GStreamer to add a plugin, however we first should > work with the external community to get the plugins ready for use. > Could you follow up with the GStreamer community and find out if there > is any way we could help get these plugins migrated to gst-plugins-good > or if there are any alternatives? From the coherence author, Coherence does audio transcoding only currently. The video pipeline was for testing purpose on PS3 and the video-transcoding part is still under development. Some cleanup will happen when it's released and "the availability of the needed elements will be checked in advance". It's not sure for now which gstreamer plugin elements will be used though. I'd suggest to follow up with the upstream GStreamer community when the Coherence video transcoding is finalized. Will also keep the contact with coherence community. We can always disable some of the features in OpenSolaris if the gstreamer elements used aren't part of gst-plugins-good(base). > In other words, some features of coherence might be disabled unless > the user installs their own GStreamer plugins to enable the features. > And some of these features may have further licensing requirements > that users might need to address in order to use those features. Agreed. Best Regards, -Alfred
