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<[email protected]>:
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
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