WMV recording

[komal]

I record tv in WMV format at 640x480, I've got a 2700+ with 1 gig of ram, hard drive is decent, wd1200jb. Anyways, whenever I record, it takes up 100% of the CPU, but the tv is still laggy, and you can notice how laggy the video is, problem is, that lag is ALSO how the video is recorded. Can't you guys work on optimizing it for the next revision?

[Bryce]

what is your video card, and type of capture card??

sounds like you are using software encoding... and software encoding is a CPU heavy process.

[komal]

I know that it's software encoding, and I know that software encoding is CPU heavy, but doesn't hardware encoding only work if you're recording in mpeg2 format? Anyways, I don't mind that it's CPU heavy, I mind that the video ends up looking laggy.

[komal]

Oh, btw, vid card is 9500 pro, it plays everything fine, problem is the video is recorded choppy. Capture card is a mercury/kobian tv tuner. Not the greatest, but it works.

[Ziffelpig]

I believe your problem lies with your capture card. It's probably based on the Brooktree BT8x8 or Conexant variant chipset, which for the most part are garbage.
Are you using the capture software that came with the card? If you are take a look at these free alternatives.
http://virtualvcr.sourceforge.net/
http://freevcr.ifrance.com/freevcr/index-en.html
Virtual Dub has a WDM mod as well.
Try using the highest resolution 720x480 for capturing it's usually the optimum for these types of cards though you would think a lower resolution would work better.Then try capturing at 352x480 if available.
You may have to look at capturing to VideoCD 352x240 CBR 1150k at 29.97fps.
Videohelp.com is a great resource for capture advice or any other video related problem.

[komal]

Umm...I'm using beyondtv.

No idea what chipset it's based on, but since WMV recording is the only thing that's choppy, I doubt it's my card's fault.

[ricflair]

Most software cards have a hard time keeping up 30 fps when doing anything higher than 352x240 or 320x240. 640x480 is extremely hard for older capture cards to keep up at 30 fps.. like even my WinTV FM shows it's stats as 352x240 or 320x240 at 30fps.. but the 640x480 capture spec only offers 15 fps consistantly. so I'd assume even with a 6 gigahertz pentium 4, you'd still have issues due to the capture cards limitations.. Most of the software cards on the market today have a rough time consistantly working by capturing at 640x480.. as mentioned above.. try 352x480 or 320x480 then turn deinterlace on and you'll get a really crisp 320x240 recording.. when I was using a software card.. I played with capture resolutions often to see what kept the CPU lowest.. if I remember back correctly.. I was able to get 352x480 captured at like 2000kbps deinterlaced into 352x240 30 fps.. looked about as good as you can get with low res analog tv anyhow.. and my CPU would sit around 60-70%. on a AMD 2400.

Thanks,
Ron

[fanbanlo]

Originally Posted by ricflair

try 352x480 or 320x480 then turn deinterlace on and you'll get a really crisp 320x240 recording..

Ron

You mean real-time deinterlace? or deinterlace @ ShowSqueeze?

I'm using PAL and now I'm recording at 352*288 @ ~800kps w/ very little noise, but looks worse than VCD sometimes.

I'm wondering if I cap in MPEG2 first (maybe 576 lines?) , then re-encode (w/ deinterlace?) into WMV9 using showSqueeze, would this help the quality even if I stay with same bitrate?

~800kbps is because my capture station is oversea. I need to download the .wmv's across a slow internet connection (~60KBps).

Thanks

[ricflair]

I was referring to deinterlacing when showsqueezing..
I had it where it would capture at 352x480 then when I squeeze it I would use 2 pass wmv with output rez of 352x240 (w/ deinterlacing enabled during the recompress (squeeze). this would make the output at 352x240 (not interlaced) at 30fps.. with the 2pass reencoding it looked very nice for the size.. the mpeg2 recording was huge but the end all wmv file was like quite small considering it had 64kbps 44hz stereo and 30fps at 352x240. That was what I used for recording t.v. shows.. but now that I have a PVR-350.. I encode at like 4,000,000 bitrate/variable bursting to 7,000,000. 128bit stereo audio and then convert to wmv format at 640x480 around 1,500,000 bitrate.. 2 pass.. the original captures are huge.. but then they are showsqueezed down to a decent size with pretty good quality.. for keeper movies.. I encode at a higher bitrate when I squeeze. like 2,000,000 bitrate which is better than VCD but not quite DVD quality (keep in mind I'm coming from an analog signal so why would I want DVD quality.. just a waste)..

[ricflair]

I'm not sure what the PAL standards are off the top of my head.. but I would try to capture mpeg if you can.. the problem with wmv capturing is that it is a compressed format so while your PC is pulling in all the data from the capture card it also has to compress is before it saves it to disk.. that's alot of work. and alot of I/O from the capture card.. not to mention memory and disk use is high.. recording mpeg will free up the processor some (however disk usage will go up some).. but there's less "work" for your system to do.. it basically gets the data from the capture card and just saves it to your hard drive.. then with the high res source you can quality showsqueeze(reencode) the show... so capture at like 2,000,000-4,000,000bitrates mpeg2 in whatever mpeg2 standard dimentions you can.. then have the show squeezed using 2/pass.. I try to capture the mpeg with higher vertical resolution so I can deinterlace it and it halves the verticle resolution.. which in my opinion makes the capture look better..

The last mpeg software recording I did was I think at 352x480 with a bitrate of like 3,000,000.. this made a large file.. but then I immediately have Beyond TV squeeze is into wmv at 352x240(288 in your case I guess) with a bitrate of about 1.1 lilke VCD and they looked pretty good.. no lost frames.. a solid 30fps.. whereas when I tried capturing right to wmv.. at 30fps 352x288 I would get skipped frames and the CPU would linger around 80-100%.. I've noticed anytime the CPU gets above 80-85% I start seeing dropped frames periodically.. the mpeg method gave me a smooth 30/fps and the CPU was only at around 40-50% during capture... sure the reencoding squeeze is a huge waste of time.. but blame your capture card and cpu.. it's hard to pull in multiple megabtyes of video/audio from a PCI card.. then process it inline/compress it/ then store it on the hard drive..

I hope to see the ability to record mpeg with my high end PVR-350 with high bitrate.. save it to disk.. then have Beyond TV showsqueeze it to DivX with slow reencode for best quality/size.. after all the mpeg will be deleted after capture.. but that way we'll get awesome quality that will be DVD ready with the mpeg capture.. to burn.. or we can archive once compressed into DivX..

[fanbanlo]

Have you tried DivX at same bitrate/res.? How does that compare to WMV9?

So you're saying, cap MPEG2 at double horizontal res. and deinterlace & resize back to 352x288 (pal) in WMV9, correct?

My system is a P4 2.8 with 512 DDR400 Dual-channel mem.

Do you know how long would it take to re-encode to WMV9? I know WMV encoder is optimized for SSE2.

[ricflair]

Yes.. That is the way I had been recording with my analog card and it came out pretty nice.. and the CPU usage during capture wasn't too bad.. end all quality was pretty good.. as for how long it took to reencode to wmv.. it took awhile but I don't remember the actual times.. I know it would take a couple of hours to reencode hour long (approx 1GB) capture. but keep in mind the system then was not as powerful as yours.

Ron