Canvassing for Linux support for Startech PEXHDCAP

[Steve Cookson]

Hi People,

I just wrote an email to this group about the Hauppauge 01381. Really i=
t=20
was a fall-back choice. If I can't get anything else then that might b=
e=20
my only option left.

But here is my preferred choice. The Startech PEXHDCAP.

It costs about $100 here:

http://www.amazon.com/StarTech-com-Express-Video-Capture-1080p/dp/B007U=
5MGBE/ref=3Dcm_cr_pr_product_top

Here is a review of it:

http://www.videogameperfection.com/av-gear/startech-pexhdcap-hdmirgbvga=
component-capture-card-review/

Here is the spec:

http://www.startech.com/AV/Converters/Video/PCI-Express-HD-Video-Captur=
e-Card-1080p-HDMI-DVI-VGA-Component~PEXHDCAP#tchspcs

But the main spec points (for me at least) are

- It's based on the Mstar MST3367CMK chip as are many similar cards,
- It's PCIe connection
- It has inputs of:
--- Component Video (YPbPr)
--- DVI-I (plus a vga adaptor)
--- HDMI
--- Stereo Audio
- Maximum Digital Resolution: 1080p30
- TV input resolution: 1080i/p, 720p, 576i/p, 480i/p
- PC input resolution: 1920x1080, 1440x900, 1280x1024, 1280x960,=20
1280x720, 1024x768, 800x600
- MPEG4/H.264 hardware compression.

But:

- OS Compatibility Windows=AE

There are already a number of positive reviews for this card around the=
=20
place together with it's twin the Micomsoft SC-500N1.

I would like to ask for expressions of interest for putting together a=20
group of like-minded interested people to build an open source v4l2=20
driver and associated gstreamer bits and pieces, together with=20
specifying any hardware that might be required. I'd like to identify o=
r=20
specify any (cheap) converters, sync splitters and the like which would=
=20
make it work for the full range of signals (eg Composite and S-video -=20
that s-video-like mini-port in the picture is actually a YPbPr Componen=
t=20
input).

I would be great for gaming, medical image capture, university and=20
research purposes.

Please let me know what you think.

Regards

Steve.

[Devin Heitmueller]

http://www.startech.com/AV/Converters/Video/PCI-Express-HD-Video-Capture-Card-1080p-HDMI-DVI-VGA-Component~PEXHDCAP#tchspcs
But the main spec points (for me at least) are
- It's based on the Mstar MST3367CMK chip as are many similar cards,
- It's PCIe connection
--- Component Video (YPbPr)
--- DVI-I (plus a vga adaptor)
--- HDMI
--- Stereo Audio
- Maximum Digital Resolution: 1080p30
- TV input resolution: 1080i/p, 720p, 576i/p, 480i/p
- PC input resolution: 1920x1080, 1440x900, 1280x1024, 1280x960, 1280x720,
1024x768, 800x600
- MPEG4/H.264 hardware compression.

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.

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).

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.

Devin

[Steve Cookson]

Post by Devin Heitmueller
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.

Post by Devin Heitmueller
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.

Post by Devin Heitmueller
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.

Post by Devin Heitmueller
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

[Devin Heitmueller]

Post by Steve Cookson

Post by Devin Heitmueller
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.

Nope, the opposite. In order to compress the video you need to store
enough context to look for repetition. H.264 encoders can vary in
latency, and in fact some can be adjusted to reduce latency at the
cost of compression performance. But they will always have more
latency than just reading the raw video as it comes in.

Post by Steve Cookson
If this is stored in a file, somehow it needs to be encoded, I just imagined
that metal was faster than code.

If your intent is to store the video in a file, then you almost
certainly will need to encode it with a scheme such as H.264. However
raw capture cards can be very useful for cases where you want to take
in the video, alter it somehow, and then put it back out to the
display (think digital signage). Capturing raw video also allows the
consumer to have better control over the actual compression process
(since it's done in software), which is why it is preferred for
professional capture application (which is why BlackMagic doesn't make
any cards with hardware encoders). Cost isn't a concern and those
sorts of customers are willing to have high end workstations to
actually work with the uncompressed video.

Post by Steve Cookson

Post by Devin Heitmueller
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?

The Mstar chip encodes the analog signal to a digital format. The
saa7160 takes the resulting digital signal and makes it available to
the host via DMA.

Post by Steve Cookson
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.

The "extra" chip is for SDI capture, which isn't supported by the
lower cost mstar chip (which is designed for HDMI and component). The
bridge is the chip nearest the PCIe connector, which can be a saa7160
or some other component.

Post by Steve Cookson
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.

Who knows? So much of that junk on alibaba is cut/pasted from other
products and isn't actually accurate. Or maybe somebody does have a
driver. There's nothing in the mainline kernel though.

Post by Steve Cookson

Post by Devin Heitmueller
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.

The Blackmagic boards are the only low cost boards out there which
have readily available drivers. The downside is you have to deal with
their proprietary interface that isn't remotely V4L2 compatible (and
thus only works with their applications or if you're prepared to write
your own app).

We wrote open source drivers for a couple of the ViewCast boards which
do HDMI/DVI capture, but while the drivers are free the boards
themselves can cost a couple thousand dollars.

Post by Steve Cookson

Post by Devin Heitmueller
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.

Yup. We've been through the exercise several times with various HD
capture boards. Adjust the multiplier based on the level of
experience of the developer doing the work. :-)

Devin

[Steve Cookson]

Nope, the opposite. In order to compress the video you need to stor=

e

enough context to look for repetition.

Ok, quite intuitive, once you know what to look for.

Yup. We've been through the exercise several times with various HD=20

capture boards. Adjust the multiplier based on the level of experience=20
of the developer doing the work.

So it is do-able. That's good to know.

If I want to capture 480i/576i and 1080i analogue my alternatives seem=20
to be:

- Something like Dazzle, $50 (480i/576i only - s-video and composite),
- Intensity Pro, $200 (480i in s-video and composite, plus, 480i/576i &=
=20
1080i in Component but YPbPr only). S-Video and Component in 480i/576i=
=20
seem to have very similar picture quality.

Which leaves me with how to capture RGBS 1080i composite synch.

What do you think of Epiphan VGA2USB (with the internal PCIe mounting=20
kit)? The basic model at $299 doesn't cover RGBS, but it does do=20
1080i. Maybe I could use a sync splitter and inverter, like the=20
LS1881n, to make the RGBS composite synch fit the VGA H+V pins. The LR=20
at $799 doesn't seem to capture 1080i. I thought it did, but now I loo=
k=20
at the website again, I can't see it. Have you used it? If not those=
=20
then there is only the HR at $1,600 :(

But Epiphan appears to support v4l2 and gstreamer. Is it fast? I gues=
s=20
it doesn't do S-Video and Composite.

If not Epiphan then what? The Epixinc PIXCI=AE A310?

It seems quite a hard problem.

Regards

Steve.