On 16/09/2013 19:09, Devin Heitmueller wrote:
> To be clear, this card is a *raw* capture card. It does not have any
> hardware compression for H.264. It's done entirely in software.
Ok, well I misunderstood that. And, in addition, I also thought that
hardware encoding *reduced* latency, something you seem to indicate is
not true.
If this is stored in a file, somehow it needs to be encoded, I just
imagined that metal was faster than code.
> Aside from the Mstar video decoder (for which there is no public
> documentation), you would also need a driver for the saa7160 chip,
> which there have been various half-baked drivers floating around but
> nothing upstream, and none of them currently support HD capture
> (AFAIK).
Well the chip thing is confusing me.
1) I don't understand the difference between the MST3367CMK-LF-170 and
the saa7160. Is one analogue and one digital? Or do they perform
different steps in the process (like one does encoding and one does the
DMA thing?
2) If you look here,
http://katocctv.en.alibaba.com/product/594834688-213880911/1080p_PCIe_Video_Grabber_Video_Capture_Card.html
You'll see a very similar card with an extra chip. You can just see
that it is produced by Gennum (but I can't see the number). There is
also another chip on the underside, maybe this is the saa7160? And maybe
it's on the underside of the PEXHDCAP too. This is actually the one I
saw working. As I say it was very fast and high quality, but under windows.
Scroll down and you see this:
Operation System: WINDOWS XP /VISTA/ 7 Linux 2.6. 14 or higher
(32-bit and 64-bit)
Drilling into this, it appeared the statement was more aspirational than
actual, but that it *had* been compatible, but there was not yet an
available driver. They would need to recompile something to include the
latest linux libraries before it would be possible to write the
drivers. I've no idea what this could mean. Although 2 clients had
indeed written gstreamer drivers, one was Cisco systems, but had kept
the code to themselves.
> and none of them currently support HD capture (AFAIK).
What does this mean? No saa7160 drivers, or no drivers period? I have
the Intensity Pro doing full-screen 1080i capture with minimal latency,
but I hate the decklinksrc module. It just does nearly nothing. Maybe
it could be re-written for v4l2src, but anyway it only accepts YPbPr, as
I said before.
> As always, a driver *can* be written, but it would be a rather large
> project (probably several weeks of an engineer working full time on
> it, assuming the engineer has experience in this area). In this case
> it's worse because a significant amount of reverse engineering would
> be required.
Kato Vision agreed with you. They were saying a few months (maybe two
or three). They didn't offer to write it, but they offered technical
support with the driver-writing.
Thanks for your input.
Regards
Steve
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