[mythtv-users] FYI - New HW video accellAPI from NVIDIA

[Jack Perveiler]

On Wed, Nov 19, 2008 at 1:18 PM, Steven Adeff <adeffs.mythtv at gmail.com>wrote:

> On Wed, Nov 19, 2008 at 11:58 AM, Brad DerManouelian
> <myth at dermanouelian.com> wrote:
> > On Nov 19, 2008, at 6:03 AM, Steven Adeff wrote:
> >
> >> On Wed, Nov 19, 2008 at 12:05 AM,  <lindsay.mathieson at gmail.com>
> >> wrote:
> >>>> or plug all those HDMI connections into a receiver and get
> >>>> uncompressed high quality audio...
> >>>
> >>> Not sure what you mean by that Steve but it sounds interesting
> >>
> >> The bandwidth in HDMI was set to allow uncompressed multichannel audio
> >> up to (and possibly exceeding) 7.1 at a very high bitrate which allows
> >> for very high quality audio (think better than DVD-Audio/SACD). It has
> >> been taken use of with Blu-Ray(and what was HD-DVD) and is slowly
> >> becoming the replacement for the old DVD-Audio/SACD debacle for music.
> >>
> >> It may not be better(or worse?) than the DisplayPort thing, but it is
> >> a standard that is in place and being used quite extensively.
> >
> > DisplayPort standard allows for more bandwidth (10.8Gbps) so
> > theoretically better. HDMI 1.3 offers 10.2 Gbps which is more than
> > earlier versions, but I don't know what they offered. DisplayPort also
> > allows for great color depths and refresh rates than HDMI. Apple and
> > Dell (and probably others) have started using DisplayPort as their
> > preferred and standard port. I hope more people use it. Lots more info
> > here: http://displayport.org
> >
> > None of this has anything to do with the new nVidia API. ;)
>
> well yes, DisplayPort is designed as a digital monitor cable, HDMI was
> designed for use in hometheaters, specifically tailored to HDTV
> resolutions.
>
> from the wikipedia,
> "HDMI supports 8 channel uncompressed digital audio at 192 kHz sample
> rate with 24 bits/sample as well as compressed audio streams such as
> Dolby Digital and DTS.[14] HDMI supports up to 8 channels of one-bit
> DSD audio, which is used on Super Audio CDs, at rates up to 4x that of
> Super Audio CD.[14] With version 1.3, HDMI also supports lossless
> compressed audio streams such as Dolby TrueHD and DTS-HD Master
> Audio."
>
> so 8 channels at that high quality, or DTS-HD/Dolby-TrueHD which is
> lossless compressed, so even better possible quality. Thats way more
> than most people need/can take advantage of. Of course, fewer channels
> allows for high sample/bit rates per channel.
>
> Right, right. NVidia needs to get their driver doing audio over HDMI
> working in linux. ;-)
>

I haven't actually tested this myself, but I believe HDMI audio over MCP78
(geforce 8200) is now suported in alsa 1.0.18:

http://www.alsa-project.org/main/index.php/Changes_v1.0.17_v1.0.18

"ALSA: Support NVIDIA MCP78/7A HDMI audio"

I have this MB:

http://www.newegg.com/Product/Product.aspx?Item=N82E16813128340

It had audio problems with whatever alsa came with ubuntu 8.04 (1.0.17 I
believe), so I had to go buy a $20 sound card.  According to the alsa lists
it got fixed for 1.0.18 but I haven't been brave enough to mess with it yet
(my wife would kill me if I ruined my working frontend right now).

So if somebody wants to give it a go and then report how it went I'd be all
ears :)

--Jack
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