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Re: [RFT] Major snd_hda rewrite Alexander Motin Fri Feb 03 02:02:26 2012

On 01/24/12 15:32, Alexander Motin wrote:
On 01/24/12 14:57, Mickaël Maillot wrote:
2012/1/21 Alexander Motin <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>
From that description I can conclude that you are passing through
compressed DTS-HD and TrueHD streams to the receiver. What are the
bitrates of streams you are playing? It looks like your receiver
doesn't receives all data. If I understand right, to transfer with
compressed bitrates above 6.144Mbps special High Bit Rate mode
should be activated in CODEC, when data stream occupies all 8 HDMI
channels instead of 2. I haven't implemented this feature yet as my
receiver doesn't support such HD formats.

i dont think bitrate is over 6.144Mbps.
for TrueHD files, mediainfo reports:

Format profile : TrueHD / Core
Mode extension : CM (complete main)
Codec ID : 131
Bit rate mode : Variable / Constant
Bit rate : Unknown / 640 Kbps
Maximum bit rate : 2 868 Kbps / 640 Kbps
Channel(s) : 6 channels

and for DTS-HDMA, mediainfo can't calculate it, but from description,
all tested file have bitrate below 3689 kbps

Then make sure that your player properly sets "sampling rate" for the
playback. Data transferred as "16bit stereo", but depending on bit rate
may have 48000, 96000 or 192000Hz sampling rate (up to 1.5Mbps, 3Mbps
and 6Mbps respectively). For higher bit rates stream transferred as
8-channel (High Bit Rate mode) with same set of frequencies (but now up
to 12, 24 and 49Mbps).

I'll try to make a patch for it a bit later and send you to try.

i'll be happy to try it.

Here is it: http://people.freebsd.org/~mav/hda.HBR.patch
It should activate HBR mode if you try to play stream with AC3 format and 8 channels (>6Mbps).

Until that time, is it possible to make your xbmc to decode those HD
streams into different number of uncompressed LPCM channels to play
it that way?

yes, it's just an option.

It would be interesting to test 6.0, 6.1, 7.0 and 7.1 LPCM
configurations with your receiver. Or at least normal definition 7.1
playback would be interesting to test (you can just set vchanformat
to s16le:7.1 or s32le:7.1 and play anything).

i sucessfully tried 6.1 and 7.1 LPCM in 16 bits.
just a small channel order issue (center and a surround back inversion)
which can be solved easily.

In what number of channels which channels are swapped specifically? I've
compared mapping I am setting in driver with data I have and found no
problem. What channel order for 7.1 uses xbmc? sound(4) uses: Left,
Right, Rear Left, Rear Right, Center, LFE, Side Left, Side Right. I've
never could check what mplayer thinks about it because I have no such
such media. Can you give me some example?

i'll add 32bits support in XBMC later for my test but from what you say,
it'll not work because 8 channels / 48khz / 16 bits = 6.144 Mbit/s.

6Mbps limitation is only for data, as they use only two channels by
default. Audio stream has no such limit.

Alexander Motin
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