Friday, July 18, 2003

Audio/Visual Sync

Well, I'm bugged with the A/V sync issue, that and a 1/1000 dropped frames problem. The dropping 1 in 1000 frames is bugging me because I had gotten to the point where I was getting only 1 in 5000 dropped frames. Virtual VCR offers a dynamic audio resync option, but that drives my frame rate lost up to 1 in 100 (ewwww). Gotta solve the frame drop problem first (yes, I've turned off the AntiVirus software and other background software).

Setup:
Asus A7V266E Motherboard
Athlon XP 1800+ CPU
512Mb PC2100 RAM
FastTrak100 RAID (built-in to motherboard)
(2) IBM DeskStar 7200rpm ATA/100 75Gb drives
(1) IBM DeskStar 7200rpm ATA/100 40Gb drive
ATI All-In-Wonder Radeon 32Mb AGP
Santa Cruz PCI Soundcard
Adaptec AUA-3100LP USB2 PCI controller
(2) 60Gb USB 2.0 drives

The O/S (Windows 2000) is installed on the 75Gb RAID1 mirror. The (2) 60Gb USB 2.0 drives are used to store video captures that I've not yet started to process (or am in the middle of processing). Video capture was being done to the 75Gb RAID1 drive (defragged and mostly empty) but I'm thinking this might be the cause of dropped frames (even though the drive is well within it's performance abilities).

So I dropped the 7200rpm 40Gb drive in, hooked up to the ATA/100 interface on the motherboard. Makes a big difference (not that the Promise FastTrak100 was ever a slouch when it comes to performance) in dropped frames. 0 for 5000 at 3 minutes into a capture instead of my usual 5-25 dropped frames - and that's at 720x480 YUV2 PicVideo MJPEG Q19 (2.6Mb/sec or so).

So... since I got zero dropped frames on a 3 min capture by writing to the 40Gb scratch drive, I went back and turned on A/V sync (dynamic mode) in Virtual VCR. That means that Virtual VCR will add audio samples to the audio stream to make the two match up. That's giving me zero dropped frames as well (low-key woot) so I'm going to go re-cap that 1 hour set of cartoons (VHS tape in LP mode, rather poor source material) and see if the audio stays sync'd up.

Assuming that issue is finally put to bed (I'm 0 for 14,000 frames currently) and the dynamic A/V sync works, my next step is to do a quick-n-dirty transfer to DVD using EasyCD Creator6.

FYI, 54 minutes into a cap now (97,000 frames) with zero dropped. Audio sync problem is fixed, but introduces another problem - "pops" in the audio stream.

posted by Wuphon's at 9:07 PM