HD audio bitstream, not PCM in linux - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 4 Old 05-28-2012, 05:19 PM - Thread Starter
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Hi, I`m running ubuntu 12.04 and xbmc on a Core i3 and Nvidia GT430.

I've tried to setup the system to bitstream HD audio (TrueHD, DTS-HD) without any luck and my question is therefore; is it at all possible to bitstream HD audio on linux or is it hopeless? I have tried xbmc, vlc and mplayer without getting anywhere (except PCM which I dont want). Should I just give up or is it hope?

Thanks in advice.
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post #2 of 4 Old 05-28-2012, 06:19 PM
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post #3 of 4 Old 05-29-2012, 04:28 PM
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I don't use XMBC, I use MythTV. But I have the same video card, and MythTV since version 0.24 streams HD audio just fine with it. So the hardware and the OS are not the limiting factor.
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post #4 of 4 Old 05-29-2012, 06:40 PM
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Mythtv docs re: HD Audio passthrough


Shows Mythtv setup screen shots and a table with known working video cards with HDMI audio passthrough


To support DD+ and DTS-HD HR ; your audio card must support stereo output at 192kHz.

Audio/Video cards known to support it:

ION and 9400M IGP : provided you use a kernel newer than 2.6.32 (it is not supported in kernel 2.6.31 and earlier)
nVidia GT2xx
nVidia GT4xx
nVidia GT5xx
Some Intel HDMI graphics chipsets (in particular IbexPeak (0x80862804), CougarPoint)

Audio/Video cards known not to support it:

Most ATI card (many only support 48kHz)
Intel HDMI graphics chipsets Cantiga, Eaglelake

To check for actual support, run mythfrontend and go into Setup -> Audio. If the E-AC3/DTS-HD flag is enabled, it is likely that your audio card supports it. Remember you must use an HDMI connection. Optical or coaxial SPDIF will *not* work.
TrueHD and DTS-HD MA support

For your audio card to support loss-less HD audio passthrough (TrueHD and DTS-HD MA), your audio card has to support HBR.
You can check DTS-HD/TrueHD support on Linux by checking for "HBR" text in "Pincap" line in /proc/asound/cardX/codec#Y. This doesn't guarantee in any way that your audio card will support HBR ; but if you don't have it, it's very unlikely that it does.

Chips known to support HBR:

nVidia GT4xx
nVidia GT5xx

Chips known not to support HBR:

ION first generation
nVidia 9400M IGP
nVidia GT2xx (*)
nVidia 8xxx, 9xxx

(*) Though not officially supported, HBR works to some extent with nVidia GT2xx ; your mileage may vary. It is highly dependent of the combination between audio processor/amplifier and video card.

You'll need a recent linux kernel (>= 2.6.36) that contains the required ALSA drivers (>= 1.0.24. Version can be found in /proc/asound/version).

Alternatively, Ubuntu users can grab the latest backported drivers from the daily ASLA ppa

Or the latest ALSA drivers can be compiled from the git repository

git clone git://git.alsa-project.org/alsa-driver.git alsa-driver
git clone git://git.alsa-project.org/alsa-kmirror.git alsa-kmirror
cd alsa-driver
sudo make install

Alsa library 1.0.23 is the required minimum. However if you had to mess with the device name to get basic audio working, it is strongly recommended you get a new version as otherwise you will likely have to mess with alsa configuration file.

git clone git://git.alsa-project.org/alsa-lib.git alsa-lib
cd alsa-lib
sudo make install

Checking your TV / Amplifier / Audio Processor capabilities
With ALSA 1.0.25 or later, Linux kernel 3.3 or later

Provided your hdmi device (TV or amp) was powered on before your PC started, Myth can display the audio capabilities of the device.

Go into Setup -> Audio. Select one of the ALSA:hdmi audio output device. In the description section, it will show the name of the connected device as well as the list of all the digital codec supported being one of the following:

DSD (One Bit Audio aka SACD)
MPEG Surround

As of Myth 0.25, only LPCM, AC3, DTS, DTS-HD and TrueHD are supported, with the caveats mentioned in the earlier section.

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