Digital to Analog chips

[j_me]

Hello everyone,

I wanted to ask what TV tuner makers actually design their own DAC chips (I would call them analog to digital, since the analog signal is converted to digital, but that's a different story).

As far as I know, Ati makes their own chips, the Theater series. That's why I have two all-in-wonder cards - Rage 128 pro AIW PCI, Radeon 7500 AIW PCI and I'm trying to get one Powercolor TV Wonder 650 PCI (DVB-T version).

But Ati doesn't really make laptop tuners. There is a USB model, but that one is big enough to look like another laptop near your laptop, and it's for the US standards only - NTSC and ATSC.

So I tried to remember what a guru once told me: Ati and Canopus make their own DAC chips. I'm not really in the mood for digging around for an expresscard tuner from Canopus.

But I did find a Pinnacle hybrid offering named PCTV 320cx. Well? How about that? Good DAC? I'm gonna be capturing video mostly, not really watching TV (much less anyway). Is it any good?

Thank you for reading this

[jagabo]

DAC? I think you mean analog to digital for video capture, not digital to analog (DAC) for video output.

[j_me]

oh so that's what DAC means...good. Thank you. Yes, I meant analog to digital, like the Ati Theater chips, Conexant/Brooktree BTxxx on average TV tuners, Phillips also makes such chips...

[edDV]

oh so that's what DAC means...good. Thank you. Yes, I meant analog to digital, like the Ati Theater chips, Conexant/Brooktree BTxxx on average TV tuners, Phillips also makes such chips...

There is much more to these cards than A/D, D/A. ATI tuner/display chipsets are explained here
http://www.amd.com/us/products/desktop/chipsets/Pages/desktop-chipsets.aspx

You can discuss ATI chipsets here
http://forums.amd.com/forum/index.cfm?forumid=1

NVidia chipsets are overviewed here
http://www.nvidia.com/page/products.html
http://www.nvidia.com/object/geforce_family.html

Do you have a more specific question?

Analog capture can be to various PC or studio formats. Popular formats are:
Uncompressed 4:2:2 YCbCr 10bit/component
Uncompressed 4:2:2 YCbCr 8bit/component
Uncompressed 8bit/10bit SDI (SMPTE 259M)
DV format
DVD ready MPeg2
MPeg h.263
MPeg h.264
Divx
etc.

[j_me]

yes, I do. I want to know who makes their own analog to digital chips. I heard Canopus and Pinnacle do that. True or false? Anyone else?

[edDV]

These cards are more integrated than that. Canopus makes analog to DV and analog to MPeg chipsets. That would be A/D plus digital encoder. The DV chipset also included DV decode and D/A.

The ATI and NVidia chipsets are described above. Pinnacle mostly uses third party hardware in consumer products (e.g. Connexant, Philips, etc.). They also have pro products.

Lower end ATI tuners use third party parts (e.g. Connexant, Philips, etc.). The upper end "All-in-Wonder" cards use the intergrated "Theater" chipsets.

[jagabo]

And for the most part, standard definition video A/D is pretty mature. There's not much difference at that level. The differences come more from hardware implementation (low noise, analog filtering), firmware, drivers, and software.

[j_me]

ah, thank you all for the replies. And so, I need not worry about the video quality of this little device, right?

http://www.pctvsystems.com/Products/ProductsEuropeAsia/Hybridproducts/PCTVHybridExpres...B/Default.aspx

[edDV]

Pinnacle consumer products are very poorly documented. You need to find a review by somebody capturing analog video with it. It isn't clear if it will capture uncompressed or force an encode to MPeg2 or Divx. If you want to edit or filter is is better for image quality to capture uncompressed.

[j_me]

I'm pretty handy at transcoding and all that, so yes, I know about the advantage of uncompressed video. Lagarith, anyone?

Yes, I'd love the software to be able to capture to avi with the codec of my choice. I will seek a review.

But in the meantime, why not use the good old VirtualDub? Even Nerovision (bundled with the Nero packages) allows you to record to avi with the codec you need. They most probably detect the device from Windows, so why use the bundled application?

And how about this one?

http://www.avermedia.eu/avertv/UK/Product/ProductDetail.aspx?Id=289

I forgot to add Avermedia to the list. Do they implement things well ? I'm pretty confident they also use other people's chips (Phillips, Conexant and whoever else).

Also, another issue comes to mind: Avermedia has one tuner for expresscard 34 and one for expresscard 54. Pinnacle only has a model for expresscard 34. The 54 cards are simply wider. I have no idea if the slot actually has more bandwidth and wether 54 cards actually use it

I have no idea which one is better (Avermedia has hardware mpeg-4 encoding) but as far as brands go, I have a better image of Pinnacle rather than Avermedia. Completely subjective though. I won't stick to their tuner just because of their name.

[edDV]

I'm pretty handy at transcoding and all that, so yes, I know about the advantage of uncompressed video. Lagarith, anyone?

Yes, I'd love the software to be able to capture to avi with the codec of my choice. I will seek a review.

But in the meantime, why not use the good old VirtualDub? Even Nerovision (bundled with the Nero packages) allows you to record to avi with the codec you need. They most probably detect the device from Windows, so why use the bundled application?

Most of the current generation "external" capture cards do not allow uncompressed capture in hardware. They must output compressed. If this were the case, VirtualDub would only see MPeg or Divx.

Most PC card designs are just external designs with a PC card interface tacked on. You need to dig deeper to see if they allow uncompressed capture. You might get that info from the manufacturer or in a product specific forum.

[jagabo]

ah, thank you all for the replies. And so, I need not worry about the video quality of this little device, right?

You don't need to worry about which A/D chip they use. But you still need to worry about whether the guy(s) who designed the entire device knew anything about handling analog video input -- how to avoid digital noise from contaminating the analog signals, how to separate chroma and luma from a composite signal (if necessary), things like that. If the device uses a hardware MPEG 2 or Divx encoder chip the situation is further complicated by the fact that this is usually done with a chip separate from the A/D chip. Firmware within the device may not make the best use of the chips. Using the wrong combination of chips may not work well. Many companies making these sorts of devices have a minimal knowledge of video capture and just slap together a few chips along with some sample code from the chip manufacturers. The digital engineers probably have little knowledge of analog electronics. The code may be hobbled together by a low level programmer who isn't given time to figure out how best to utilize the hardware and barely manages to put together something (almost?) works.

Even if the right combination of chips is selected, the device is designed properly, and the internal firmware is well written, the capture driver installed in the computer can still screw things up.

The only way to evaluate which cards are best is to look for reviews from people that know something about capturing video and have other devices to compare to. Or buy a bunch and compare them yourself.

Also note that devices that capture digital broadcast usually just save the broadcast stream to a file. If the broadcaster is sending a 480x576 interlaced MPEG 2 stream at 5000 kbps, that's what you get.

VirtualDub cannot capture from many hardware encoder devices. You often have to use the software that came with the device.

[j_me]

Thank you. None of the two convinced me - from people's general reviews, both look like what jagabo described them. The Pinnacle offering is old, the AverMedia offering heats up, has no remote, etc.

I was hoping for something like this, but for PAL/DVB-T and smaller (USB stick-sized or ExpressCard-sized). With that kind of size you're almost carrying two laptops (over 11 inches long - about 30 centimetres, and quite heavy). But I assume the image is good.

Maybe, in the future, Ati will make a much smaller version of this for the USB or ExpressCard. Who knows.

[jagabo]

I was hoping for something like this, but for PAL/DVB-T and smaller (USB stick-sized or ExpressCard-sized). With that kind of size you're almost carrying two laptops (over 11 inches long - about 30 centimetres, and quite heavy).

Are you sure it's 11 inches? The specs say "11.6875 X 8.9375 X 2.875" but don't say if it's inches or centimeters. If it's inches and the remote is to scale the remote is something like 15 inches long! I suspect the dimension are the box it comes in, not the product itself. I suspect the enlarged image is close to the actual size -- ~13 cm long. The weight is listed at only 0.5 pounds.

Looking at the TVW650PCIE, a half height PCIe card, the dimensions must be in centimeters.

http://www.diamondmm.com/productmatrix1.php?family=VFZXNjUw

[j_me]

Makes sense. Yeah, it's probably centimeters but it's still NTSC/ATSC. The Ati Theater chip inside will probably work with PAL (it's advertised as being able to decode any analog signal on AMD's website) but it will certainly not decode DVB-T. And if you take your laptop with you, that's what you get in this country: over the air PAL and DVB-T.

So maybe they'll make a DVB-T version, have to wait for that.

[j_me]

What do you know...

http://www.amd.com/us/products/pctv/tv-theater/Pages/tv-theater-specs.aspx