Wednesday, July 16, 2003

Capture Stuff

Doom9 Capture Guide

NTSC frame rate is 29.97, but VirtualDub has to have it set to 29.9697 due to some sort of rounding error (my guess, the source wasn't real specific as to the why and wherefore).

Trying out the Virtual VCR product combined with Huffyuv v2.1.1 (I'll dig up links for those later). Reason I'm using Virtual VCR is that the All-In-Wonder Radeon card doesn't have Video for Windows (VfW) drivers, instead it has WDM drivers (which VirtualDub won't use).

Attempting to capture 640x480 YUV2 29.97 fps using the Huffyuv v2.1.1 (predict median best). Audio was 16 bit 44Khz stereo, packed to Microsoft ADPCM 44Khz stero. CPU usage was 52%, but disk rate was 6.5Mb/sec or so which resulted in rougly 0.5% dropped frames.

Tried again at 352x240 YUV2 29.97 fps, Huffyuv v2.1.1 (predict median best), 44.1Khz 16bit stereo audio, Microsoft ADPCM 44.1Khz stereo. While the data rate dropped to 2Mb/sec, and CPU usage was only 27%, I still saw about 1% dropped frames (DirectShow reports 0 dropped frames, but Virtual VCR is able to detect dropped frames and displays that as Dropped 2 numbers).

352x240 YUV2 29.97 fps, no compression on audio or video results in a clean capture at 5Mb/sec with 35% CPU. Of course, that means 20Gb per hour of video which makes for some fun storage issues.

Supposedly, PicVideo's Motion JPEG format ($28 for personal use) is a good capture codec with good performance (they say 640x480 30fps is possible on a PentiumII, so my Athlon XP1800+ should be fine).

352x240 YUV2 29.97 fps, huffyuv 2.1.1, but this time with no audio compression resulted in a clean capture at 27% CPU and 2Mb/sec.

640x480 YUV2 29.97 fps, huffyuv, no audio compression results in 52% CPU and 7Mb/sec with 1 or 2 dropped frames per 1000 (shrug, luck of the draw). 7Mb/sec is easily doable by the hard drives that I have (Promise FastTrak100 RAID1 7200rpm) since IIRC their top tested speed was around 10-12 Mb/sec writing. However, old style AVI files are limited to 2Gb which is 4.5 min or so at 7Mb/sec. But, supposedly, VirtualDub can handle AVIs larger then 2Gb (report is that 48Gb is the practical limit though according to the author). FYI, a 24 min capture at 7Mb/sec is a 10Gb file (wheee).

posted by Wuphon's at 11:44 PM