[alsa-devel] [Intel-gfx] [RFC][PATCH] ELD routines and proc interface
wfg at linux.intel.com
Fri Nov 21 02:59:10 CET 2008
On Thu, Nov 20, 2008 at 05:46:49PM -0800, Shane W wrote:
> On Fri, Nov 21, 2008 at 09:36:55AM +0800, Wu Fengguang wrote:
> > > supports coding type AC-3: channels = 6, rates = 44100
> > > 48000 88200, max bitrate = 640000
> > > supports coding type DTS: channels = 7, rates = 44100 48000
> > > 88200 176400 192000, max bitrate = 1536000
> > > supports coding type DSD (One Bit Audio): channels = 6,
> > > rates = 48000
> > It's weird that DTS supports 7 channels while DSD supports 6.
> > DTS is simple the compressed form of DSD.
> Hmm, I thought DTS was just another way of compressing PCM
> whereas DSD is the format used on SACD disks, IE 6 channel.
Well my source is a bit different ;-)
To reduce the space and bandwidth requirements of DSD (2.8 Mbit/s per
channel), a lossless data compression method called Direct Stream
Transfer (DST) is used — DST compression is compulsory for
multi-channel regions and optional for stereo regions. This typically
compresses by a factor of between two and three, allowing a disc to
contain 80 minutes of both 2-channel and 5.1-channel sound.
> > > The speakers 0 line is a bit confusing, not sure if that's
> > Yes it's unexpected. Do you know its real speaker numbers and
> > allocations? Does it provide some number of line-out ports?
> There are six speakers connected, fl, ct, fr, rl, rr and
Takashi, I'd suggest to support writing to the ELD proc interface to
alter the internal ELD struct. This could let users debug/fix quicks
conveniently. But sure these fixes should eventually be incorporated
into the kernel so that it just works.
> > > what's doing it. I am using:
> > > aplay 51test.wav
> > >
> > > which I have put here:
> > > http://www.csy.ca/~shane/51test.wav
> > I hear only "front left" and "front right" in my T61 :-)
> Yeah, you should get:
> Front left
> Rear left
> Rear right
> and a little boom from the sub
> If you encode 51test.wav to ac3 and stream through hdmi
> directly, it does this properly.
OK, so 5.1 AC3 audio plays properly on HDMI?
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