Audio Video Sync and Dropped Frames with VirtualVCR

[dlohren]

Audio / Video Synchronization Capture Problems



Objective: Create VCDs to be used with a DVD player

Software: VirtualVCR

Hardware:
· Motherboard ECS K7S5A
· 768 MB DDR RAM
· AMD XP+1800
· ATI TV Wonder capture card using composite video input
· Sound on motherboard input using Line In
· Audio / Video Source: VHS

Capture File Details:
· 352 x 240 resolution
· PCM Audio
· Huffyuv video compression

Test:
I captured 45 minutes of the same VHS signal using four AVSync options used in VirtualVCR (Audio Resample 100.00%, Audio Resample Dynamically, Video Master Stream, and also without any AV Sync applied). I collected the AVDiff.txt file for each capture.

RESULTS: All of the files are approximately the same size - 6.5GB. All of the files exhibit dropped frames (dropped02) in the same pattern: after capturing for approximately 9 minutes, framedropping begins. After 45 minutes, all have dropped approx 350 frames. The 'audio resample 100%' and 'resample dynamically' are slightly out of sync (0.2 seconds) and the video frequently "jumps" toward the end of the file. The other two files exhibit audio out of sync with video by 10 seconds.

I can provide these AVDiff.txt files or graphs of this data.
Email me at dlohren@hotmail.com

Thanks

[ImaWeTodd]

I am far from an expert at this, but here are some thoughts:

- Post on the VVCR forum http://forum.digtv.ws/. The author seems to get back quickly.

- It's your hard drive (i doubt it) Test with an mjpeg codec. You will write less data.

- It's your source signal. Test with another source like cable tv. Maybe the card has problems with the signal.

- What drivers are you using? I believe the drivers from http://btwincap.sourceforge.net/ work with this card.

Hope this helps give you some ideas. I have a Aver card, and use the btwincap drivers and VVCR. I can cap 352x480 on a P3 700 with picvideo mjpeg 19 quality, and I get 0-20 dropped frames over 1/2 hour. VVCR also does a great job on the audio sync.