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On 11/18/2011 10:16 AM, Colin Guthrie wrote:
<blockquote cite="mid:ja63s2$sto$1@dough.gmane.org" type="cite">
<pre wrap="">'Twas brillig, and Kelly Anderson at 18/11/11 16:37 did gyre and gimble:
</pre>
<blockquote type="cite">
<pre wrap="">On 11/17/2011 11:41 PM, Maarten Bosmans wrote:
</pre>
<blockquote type="cite">
<pre wrap="">2011/11/17 Kelly Anderson<a class="moz-txt-link-rfc2396E" href="mailto:kelly@silka.with-linux.com"><kelly@silka.with-linux.com></a>:
</pre>
<blockquote type="cite">
<pre wrap="">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.
</pre>
</blockquote>
<pre wrap="">Note that there's nothing inherently high-definition about the audio
data through a hdmi connector.
</pre>
</blockquote>
<pre wrap="">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.
</pre>
<blockquote type="cite">
<pre wrap="">
How about also adding 4.0 and 5.1? That seems more complete.
</pre>
</blockquote>
<pre wrap="">They weren't necessary for the pass-through support, although they may
be beneficial
for non-pass-through audio.
</pre>
</blockquote>
<pre wrap="">
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?</pre>
</blockquote>
This email provides the most detailed description of the what is
necessary to<br>
get the bandwidth required to do DTS-HD pass-through. The most
significant<br>
piece is the 8 channel HBR requirement. Without adding the patch at
the<br>
start of this thread I can't get it to switch into 8 channel mode to
get the 768K<br>
bandwidth.<br>
<br>
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<a
href="http://lists.freedesktop.org/archives/pulseaudio-discuss/2011-March/009364.html">http://lists.freedesktop.org/archives/pulseaudio-discuss/2011-March/009364.html</a><br>
<br>
I've perused the pulseaudio code many times looking to uncover the
secrets<br>
of the "new" pass-through code. I didn't find anything like a
conversion of raw<br>
DTS(-HD) packets to 0-padded pass-through data. So, I guess I'm
confused<br>
as to the advantage of the "new" pass-through code versus opening
the stream<br>
with PA_STREAM_PASSTHROUGH. I'd be happy for someone to unlock the
secrets<br>
of the "new" pass-through approach. BTW, all of the info on the web
covers<br>
the "old" pass-through techniques but I don't see any info on the
new techniques.<br>
It might be useful for someone to rewrite pacat.c to use the new
techniques<br>
as an example.<br>
<br>
<br>
<blockquote cite="mid:ja63s2$sto$1@dough.gmane.org" type="cite">
<pre wrap="">
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
</pre>
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