Improving the xvid setting in capturing.

[Surf]

Hi Boys,

My rig: XP+ stable @2ghz, 512mb, Philip's SAA7131 cap card.

Systray emptied, AV dis-abled.

VIRTUALvcr: 352x480, 29.97fps, uncompressed 44.1k, 16bit stereo. Target in 2nd hard drive(clean).

XVID settings:

Single pass 1270kps,NTSC cinema profile. Mpeg quantization, AQ off, IE off, QPel off, GMC off, B-VOP checked with default, Packed Bitstream(greyed). Default square pixel aspect ratio.

User defined Motion Search at 6-Ultra High, VHQ at 1-Mode Decision, VHQ for Bitframes off, Chroma Motion checked, frame drop ratio zero, Max I-frame interval at 300.

The arrived setting came from a few weeks of lurking and scrounging.

Any comment to improve the setup is appreciated. The capture seems fine so far, just concerned with upto 80-90 drop frames per hour. Then again it means about 3 seconds loss...and no audio sync issue.

Post processing is done in AVIDEMUX, chopping the commercials and AC3 the audio. Then it's stored in usb pen drive, play @work with MPC...shhhh :D .

Take it away boys and as always, :thanks: !

[Blue_MiSfit]

single pass CBR? not really a good idea. I would go for CQ3 or CQ4 if you're tight on space.

If you need to hit a set filesize, cap in HUFFYUV or some other lossless codec and process afterwards with 2 pass xvid.

I've never used virtual VCR, I would suggest trying VirtualDub, it's very well developed. That setup should *not* be dropping frames.

~MiSfit

[Surf]

CBR is chosen for real time caputre. My lowly cpu is incapable of 2-pass. The listed settings are to reduce as low usage as possible.

Tried numerous times with VirtualDub without success. In spite of setting the cap size to 352x480 VDub output it to 352x360 <<< widescreen.

Ideally I would use Huff-n-Buff if I want to dvd it. But even my 2gig usb pen drive won't be able to hold an hour's worth to view @work.

When chopped and recompressed audio to 2ch AC3, the output is quite watchable with MPC in spite of that 80-90 frame losses and no noticeable audio sync issue.

Any further thoughts?

TIA

[Blue_MiSfit]

I think you might not be understanding my suggestions.

I know your CPU is too slow for 2 pass on capture. Nobody can do that, it's just imposible.

What I am suggesting is that you capture your video in HUFFYUV. When you are done capturing, then do a proper 2 pass XviD encode and put those files on your flash drive so you can watch them at work. You mention wanting to "dvd it". Huffyuv can easily be recompressed into MPEG-2 for DVD.

If you don't want to capture in lossless and re-encode you can capture directly to XviD. I would just suggest not using CBR.

There are 2 single pass modes - CBR and CQ. CBR specifies a constant bitrate (hideously ineffecient, because XviD has to guess quantizers which leads to extensive quality fluctuation). CQ specifies a constant quantizer, which is much closer to constant quality. This is still VBR, but quality stays good.

x264 has a CRF mode as well. CRF is an even better "constant quality" mode that allows for some quantizer variation (thought not much) to improve compresion.

The only downside to CQ modes is that you have no idea how big the output will be. In practice CQ3.5 or CQ4 is a good bet for real time captures.

That said, capping in lossless and re-encoding in proper 2 pass is frequently the best option, though the most time consuming.

Also, AC3 might be unnecessary for captured analog audio. I would suggest LAME mp3 or vorbis, great quality can be had at under 100kbit for stereo

Good luck
~misfit

[Surf]

Thanks BlueM for clearing up the 2 types of single pass. It was my erroneous assumption that CBR would be less strained on the cpu than the CQ. I have noticed that I didn't mention the time restrain for I captured @10pm and transferred to the usb drive the next morning, no time for fancy ansy post production.

Other than that: do you have any comment with the settings mentioned at the very 1st post which would reduce the cpu usage/less drop frames?

[Blue_MiSfit]

Maybe disable VHQ. This will increase filesizes a bit, but VHQ is rather slow. Otherwise it looks like you have selected fast settings.

If you are still having slowness issues, you may have a rotted operating system :) Try a clean install of Windows, the solution to all software problems :D :D :D
~MiSfit

[olnima]

...and maybe set Motion Search at 5-High, enough for "normal" Films on TV. Maybe that give You some more space to higher the resolution (480*480?). If You know your source-material has got black borders, You can crop while caturing (VirtualVCR-cropFilter or ffdshow) This saves CPU-Power

All that depends on the source-video.

Olnima