On 11/18/2011 10:16 AM, Colin Guthrie wrote: > 'Twas brillig, and Kelly Anderson at 18/11/11 16:37 did gyre and gimble: >> On 11/17/2011 11:41 PM, Maarten Bosmans wrote: >>> 2011/11/17 Kelly Anderson<kelly at silka.with-linux.com>: >>>> Hi, >>>> >>>> So I patched PulseAudio 1.1 for hdmi-surround-71 and lo and behold it >>>> worked. >>>> Here's a patch, hopefully we can get this added in the next official >>>> release >>>> of PulseAudio. I know that there are quite a few Xbmc users that >>>> have been >>>> anxiously >>>> waiting for high-definition audio pass-through to work correctly. Of >>>> course >>>> if someone >>>> has a better solution, that would be fine too. >>> Note that there's nothing inherently high-definition about the audio >>> data through a hdmi connector. >> True. I should have said DTS-HD. DTS-HD requires more bandwidth then 2 >> channels @192K >> can handle. 8 channels @192K provides enough bandwidth (768K) to handle >> the high >> def audio formats such as DTS-HD. >> >>> How about also adding 4.0 and 5.1? That seems more complete. >> They weren't necessary for the pass-through support, although they may >> be beneficial >> for non-pass-through audio. > I'm confused..... > > This isn't pass through is it? I mean it's defining an 8 channel PCM > device. You do not pass it encoded DTS, AC3 etc. etc. data, but an 8 > channel PCM stream. > > Pass through is quite different, but is also supported in PA 1.1 > (provide the client application uses the new API to enable pass through). > > Isn't this just enabling 7.1 channel output, such that the application > in question does the decoding and passes the PCM stream to your receiver > equipment? This email provides the most detailed description of the what is necessary to get the bandwidth required to do DTS-HD pass-through. The most significant piece is the 8 channel HBR requirement. Without adding the patch at the start of this thread I can't get it to switch into 8 channel mode to get the 768K bandwidth. http://lists.freedesktop.org/archives/pulseaudio-discuss/2011-March/009364.html I've perused the pulseaudio code many times looking to uncover the secrets of the "new" pass-through code. I didn't find anything like a conversion of raw DTS(-HD) packets to 0-padded pass-through data. So, I guess I'm confused as to the advantage of the "new" pass-through code versus opening the stream with PA_STREAM_PASSTHROUGH. I'd be happy for someone to unlock the secrets of the "new" pass-through approach. BTW, all of the info on the web covers the "old" pass-through techniques but I don't see any info on the new techniques. It might be useful for someone to rewrite pacat.c to use the new techniques as an example. > > This isn't necessarily a bad thing to support, but I think the commit > message and such is then quite wrong (and judging from your comments, > perhaps your understanding of what is going on too might be quite off > target!) > > Col > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20111118/b72b71d0/attachment.htm>
