[mythtv-users] Swapping PCI cards kills X

Devin Heitmueller dheitmueller at kernellabs.com
Sat Oct 16 13:59:43 UTC 2010


On Fri, Oct 15, 2010 at 10:34 PM, Gavin Hurlbut <gjhurlbu at gmail.com> wrote:
> On Fri, Oct 15, 2010 at 7:11 PM, mike at grounded.net <mike at grounded.net> wrote:
>> I have no doubt that it was but it didn't answer my question in terms of the card being able to feed the audio section via system bus.
>> Some cards need to be cabled but some cards have the audio on the bus so just sends it directly to the sound card. Well, then again, I believe that's how some of the cards I've owned have worked.
>
> HUH?
>
> I think you need to read some documentation again...  The HVR-1600
> records to MPEG-2 streams from analog, and captures MPEG-2 streams
> from digital...  These streams contain both video and audio.  This is
> the same as the PVR-500.  These cards do not present themselves as
> sound input cards, and do not take sound from your sound card.  Going
> over the system bus is an MPEG-2 stream, which then gets written to
> your disk.  When you play this file back, the video goes out your
> video card, and the sound goes out your sound card (typically).  The
> HVR-1600 has no need to send anything to your soundcard over the bus
> or over cables.  It is not an old cheap framegrabber.
>
> Honestly, some research before buying equipment goes a long way :)

Gavin,

Actually the HVR-1600 can operate as a frame grabber, and does present
an ALSA sound card device to Linux in recent kernels to handle cases
where the user needs to bypass the encoder.  Example usage patterns
include video game consoles where they want to avoid latency or low
end platforms where they don't intend to do any recording and want to
avoid the cost of MPEG decoding in software.

That said, you are correct that nobody using the device for MythTV
would use it in this model, but it can create some confusion for users
who run "arecord -l" and see the HVR-1600 offering up an ALSA capture
device

Devin



-- 
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com


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