Am I trapped by my capture card?

[pburdett]

I have a Hauppage WinTV capture card of some sort and it appears the maximum capture resolution is 360x240. I am capturing primarily from Hi-8 analog camera video so I suspect I have a lot more resolution than that to offer. I am trapping myself in the very beginning of my process with poor capture video that can never be improved on?

Also, it seems to me that, even at the lower resolution, it is worthwhile outputting videos to SVCD and even XSVCD. I may not have the maximum number of pixels to play with, but I want enough bitrate to make sure that I don't lose an ounce of quality from any one of those pixels. Does that make sense? (It appears to - based on my results - but I may be doing something else wrong.)

[fmctm1sw]

What driver are you using? I'm using the one at btwincap.sourceforge.net
I can cap at 720x480 with a wintv card.

[pburdett]

I am not sure about the driver, but it will be the one that came with the card. I was not aware that changing drivers was an option, so I'll check it out.

Once I get the new driver, how do I point XP to using the new driver instead of the old one?

Also, which WinTV card are you using? Mine was the pretty cheap, so you may just have a higher grade model.

[D_Knife]

download and install the driver that fmctm1sw suggested
it will install over your existing capture driver
Most brooktree based cards - like the WinTV use almost the same chipset
you will need to do some tweaking and experimentation
and probably need to turn off full overlay viewing - either go back to preview mode or watch via a seperate TV set but it will work

[pburdett]

I am happier -- but not completely so. The new driver appears to work fine. It lets me capture at 720x480 as long as I don't try to preview the capture (or overlay, or whatever -- I don't really know the difference). I am content watching the captured material on my video camera.

My new problem is dropped frames. I thought I had this problem licked when I went with a dedicated hard drive and shut down every app and service except Windows Audio and Plug and Play (experience shows I need these). If I capture at 320x240 (which is the old situation I am trying to improve on) I can capture with zero dropped frames. At 640x480 I consistently drop a frame every 2 seconds or so. At 720x480 I drop a frame every quarter second or so.

This suggests to me that my "pipeline" may be constrained to some degree. If I try to move too much information too quickly it gets bogged down. Does this make sense? Is there something I can do to unclog the pipes? Any guesses at where the bottleneck is?

[fmctm1sw]

What kind of CPU are you running and what are the details of your hard drive?

[RoopeT]

And what codec are you using for captures? Do compress audio? Are you using any video filtering? Are you using RGB or YUV2 colorspace?

[pburdett]

I'll check on some of the details asked about, but my CPU was a pentium that was pretty close if not top of the line 6 months ago. My capture hard drive is a dedicated 60 G drive -- I'll have to check on the make. (I am at work right now.)

I am capturing in in VF using the capture driver discussed above and a WinTV card. I don't know what "codec" I am using, and as far as I know, I am not using any filters. I am using RGB24 colorspace and have no idea what that means, but I do have some other "colorspace" options to choose from. When I tried them it did not seem to make any difference to the dropped frames. My audio is being captured without compression. (i.e. 44.1).

[dphirschler]

Sounds to me like the bottleneck is the harddrive. I have the same problem. I can capture 640x480 on my 5.7gig drive, but on the 60 it will only go to 480x480. I did managet to get some extra speed by using Picvideo Mjpeg and also by using 16bit colorspace.

If you absolutely have to get it at 720x480, then set your audio settings to the worst possible settings (mono, 8bit). That will help some. Then capture the video. Capture the audio on a second pass (I like to use Exact Audio Copy for recording audio). Then use your crummy audio file as a reference to make your high quality audio file match and line up with the video.


Darryl

[pburdett]

Very creative, dphirschler! I'll try it. It is sometimes amazing to see the inventiveness that goes on in trying to piece together solutions to computer problems!

I think 640x480 will work fine for me. I would even by happy with 480x480, but I don't have that option for some reason. But I seem so close to getting all my frames at 640x480 that limiting the audio might do the trick.

If the bottleneck is indeed the hard drive, is there some way to tweak it to speed it up a bit? It is a 7200 drive and I thought that was pretty fast.

Edit: Info on my system: Pent 4 1.9gh; 512mb ram.

[pburdett]

Hey experts, there are still a few open technical questions of considerable interest to me in this thread. Like, is it really my brand new 7200 60G hard drive that is causing a bottleneck? That is pretty hard to swallow. Anybody care to weigh in?

[s_konstanty]

I had a similar problem with HDD speed. Are you using an Ultra ATA cable for your drive and is it enabled in your machine's BIOS? Also, I am told that if you have a slower drive that is not ata 60/100 compatible it will slow down the speed at which your HDD can capture video/bit rate.

[pburdett]

Here are some weird results:

I tried the "reduced audio" solution mentioned above. It did not work with 640x480, even when I reduced the audio right down to nothing - a video only capture. It was still dropping 10 to 30 frames per 10 second clip.

So I tested at 720x480 with no audio capture to see how much worse that was. Drum roll... 0 drops! So I added the audio back in at a full 44.1 MHz - still 0 drops. Also, I am sure I did exactly this same test before and was consistently dropping two frames per second. Did it take a while for the tubes to warm up or what?

Now I am tempted to shut up, knock on wood, and hope my luck holds, but I am still curious. What is going on? Any ideas?

[fmctm1sw]

burdett, I'll give you a "e" for effort dude. What I found is that the virtualdub benchmark thing will compute a megabytes per second number when you poke in the resolution and color depth and it seems to be pretty consistent with what I can capture at. I'm not sure what is happening for you. I do applaud you for trying things instead of posting every 10 minutes saying "this doesn't work and that doesn't work."

[pburdett]

I spoke too soon. While I still have some nice capture evidence that things were actually working for a while at 720x480, I can't do it any more. Back to 2 dropped frames per second at that rate. So I am still looking for suggestions. I am perhaps more frustrated than ever knowing that my machine CAN do this if the right stars are aligned.

Some more data points to consider. I find that if my camera is PAUSED in the middle of a clip when I capture I get zero drops. The drops will only kick in after I start the tape rolling. That seems wrong to me. If I am capturing uncompressed (which I believe I am) then I should be dumping the whole screen into the capture no matter if it has changed on not. Isn't that right? If it is, then why would it make any difference if my clips has motion or not?

[SilverMana]

have you checked yer dma ? and try to do a hd benchmark with auxsetup.exe in vdub that solved my dropping frame problem ...

[pburdett]

Capturing SUCCESS!

I switched the color space from RGB24 to YUY2 and stopped dropping frames. I did a bit of research on this and found that RGB24 picks up 24 bits of info per pixel, 8 for each color of Red, Green, and Blue (hence the acronym); while YUY2 is only picking up 16 bits of info. I guess that difference in the info load was enough to cause the dropping of frames.

I think YUY2 will work well for me because my ultimate destination is MPEG2 encoding and YUY2 will have more than enough color info (twice as much, I think) to drive that.

I am still not sure why RGB24 worked okay when my camera was paused. It seems to me that the color sampling should still be taking place even if there is no motion in the picture.

I will still try the benchmark thing to see if I can improve further. I will also try using the VirtualDub codec in capturing to see if it will let me do 24 bit color spacing. I guess I am using the Main Concept codec now since I am capturing in Video Factory.

[flaninacupboard]

just thought i'd say, if you use the codec huffyuv, you get yuy2, at about half the normal size. huffyuv compresses the information as it goes along, but not in the sense that mpeg or divx is compressed, more like winzip. it is a lossless codec, so whatever goes in comes out, but it halves the amount of data being sent to your hard drive, which is obviously a big benefit in your case. the other issue at hand is that poor quality/damaged video tape can cause a capture card to drop frames. i don't entirely understand the issue, but im led to believe that if a video is damaged then the "get ready for the next frame!" message never gets to your TV (or capture card, in this case) so the card never starts recording the frame.

[pburdett]

Thanks, flaninacupboard, I'll give it a try.