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| Unofficial VirtualDub Support Forums > Advanced Video Processing > Ripping Wav Audio From Avi |
| Posted by: fccHandler Nov 21 2002, 07:07 AM |
| Amigos, I posted my very first question to these forums a long time ago. Since then I've been a frequent visitor (and ultimately became a moderator) but I never received a satisfying answer to my first post. So here it is again (requires Avisynth): 1) Create the simplest script possible: AVISource("CAPTURE.AVI") 2) Save it as CAPTURE.avs 3) Open CAPTURE.avs in VirtualDub 4) Choose "Save WAV" to rip the audio From my experience, this is like 10 times faster than opening the original AVI with VirtualDub and choosing "Save WAV." Anyone else seen this? Anyone know why? (Maybe no one knows, and it's an eternal mystery...) |
| Posted by: phaeron Nov 21 2002, 08:44 AM |
| VirtualDub attempts heavier buffering than Avisynth -- or, rather, AVIFile -- for AVI files. This is very effective for high-bandwidth files, but for finely interleaved files, it can result in excessive disk I/O. The problem is particularly bad if the audio interleaving is too far off, causing cache misses in the read routine. There is a checkbox on the extended options dialog for AVI, "disable streaming I/O," that disables the readahead cache and may improve throughput. |
| Posted by: fccHandler Nov 21 2002, 06:06 PM |
| Thanks, I'll try that! |
| Posted by: fccHandler Nov 21 2002, 07:01 PM |
| Thanks so much, phaeron; it worked just like you said. Neat trick! I'm still amazed by how huge the difference is. The quick test I just did was to rip all of the PCM audio from an approx. 1G capture file: with streaming: 1 minute, 30 secs without streaming: 12 secs I'm so much happier now! |