HDMI out to TV, no sound

[Thomas Milne]

Another thing I just noticed about this video card. On the box, in very very
small print are the 'minimum requirements', which I normally don't pay much
attention to because it usually just talks about how I need Windows ;)
Anyhow, this one actually says I need at _least_ 2 GB of system memory. 2
GB!!?? Wow, I only have 1 GB, so I need to upgrade I guess...

Wow.

On Sat, Jun 4, 2011 at 11:43 AM, Russell Reiter <rreiter91-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:

> I had a further look at this information on HDMI and it seems to me
> this is what jackd is for. A udev event, although you might not even
> need that daemon to try this. I have my own problems with trans coding
> video and audio signals at the moment, this problem is a distraction
> and why I'm top posting.
>
> Try plugging the cable connected to the tv into the pc and use #lspci
> see what pin 19 shows on the bus when hot plugged. Then try udevadm
> info --attribute-walk <path and name> man udev, to see how this works.
> Assuming you get results, you might be able to use a hot plug event to
> connect the audio stream(s), using a udev rule.
>
> The hdmi cables audio transport layer carries LPCM sound, surround
> sound if your tv has output for that, which it probably does in the
> form of, hdmi in and hdmi out and unlike midi no throughput. That
> transport layer will convey the digital signal to the tv for trans
> coding. Shielding the signal from the "copper"  noise. There are three
> shields for the data and one for the bus clock. The shielding signals
> make for more efficient multiplexing of the signal, remember it's an
> RF signal. Alternatively if the tv does not do its own trans coding
> and is expecting something else in its TDMS data stream, that
> condition could most likely be overcome by udev re-assignment as well.
> In order to pass the signal through the sound card and then mix it
> back in to the stream, the appropriate udev rule could be applied on a
> hot plug event. I believe this is where jackd would fit in, making it
> easier to allow for the lack of direct pin assignments to digital
> device outputs.
>
> aplay -L will show what audio devices are detected. Although the lack
> of one to one pin assignment, as noted in the links, may be
> insurmountable without the jackd daemon to handle the kernelspace
> mappings.
>
> There is a lot of RF noise when you take an analog audio signal
> directly from the back of the computer. Better to deliver it to a
> "clean" switch digitally before converting it to analog.
>
>
> On Fri, Jun 3, 2011 at 11:14 PM, D. Hugh Redelmeier <hugh-pmF8o41NoarQT0dZR+AlfA at public.gmane.org>
> wrote:
> > | From: Thomas Milne <thomas.bruce.milne-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org>
> >
> > | If I have an HDMI out on my video card, and I connect to my TV, is that
> all
> > | I need? Should that convey the sound? The manual for the video card
> says
> > | nothing on the subject. There were no extra cables or anything, though
> some
> > | people seem to be saying you need to connect the video card to a sound
> > | device?
> >
> > It depends on the card.  I'd bet almost all modern cards with HDMI-out
> > also support sound out on HDMI.
> >
> > You were having problems with your GeForce GT 520 card.  That card
> > would have sound out.  See section 6.1.4 in
> > <
> ftp://download.nvidia.com/XFree86/gpu-hdmi-audio-document/gpu-hdmi-audio.html
> >
> > (Not sure why it is XFree86.)
> >
> > There are different kinds of audio supported on HDMI.  Not all types
> > are supported by all cards.  From <http://en.wikipedia.org/wiki/HDMI>:
> >
> >    For digital audio, if an HDMI device supports audio, it is required to
> >    support the baseline format: stereo (uncompressed) PCM. Other formats
> >    are optional, with HDMI allowing up to 8 channels of uncompressed
> >    audio at sample sizes of 16-bit, 20-bit and 24-bit, with sample rates
> >    of 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz and 192
> >    kHz.[21][45] HDMI also supports any IEC 61937-compliant compressed
> >    audio stream, such as Dolby Digital and DTS, and up to 8 channels of
> >    one-bit DSD audio (used on Super Audio CDs) at rates up to four times
> >    that of Super Audio CD.[45] With version 1.3, HDMI supports lossless
> >    compressed audio streams Dolby TrueHD and DTS-HD Master Audio.[45] As
> >    with the YCbCr video, device support for audio is optional.
> > --
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> --
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>



-- 
Thomas Milne
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