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| dangorn |
| Posted: Oct 28 2002, 12:35 PM |
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Unregistered
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I recently bought a new display adapter (Geforce4 4200), and it came with a video-in port. Naturally I've been tinkering with it, and soon realized with all my hard drive space this could make an excellent digital VCR system. I looked around for capturing software, and settled on the most excellent Virtualdub.
But I've been having a problem with audio. I haven't tried an exhaustive list of audio codecs, but so far I've had limited success. I can use most formats without problems, except for MP3 and Ogg Vorbis. I haven't tried AAC yet. I can use formats like PCM, ADPCM, CCITT, etc. just fine.
When I use MP3/Ogg, I get an insane amount of dropped frames. It's completely unusable. There is one minor exception to this: if I use a bitrate of 320kbit/sec for MP3, it works just fine. No dropped frames. Any other MP3 bitrate drops more frames than it captures.
Any idea what could be causing this? Very peculiar. I've actually been using that bitrate for my capturing, but it's a complete overkill and bloats my recordings unnecessarily.
For audio capturing, I'm using a SB Audigy. I've read that there are a few issues with SB cards, but I'm not sure they apply to my problem.
Oh, and one more thing. I'm capturing in UYVY (YUV 4:2:2 interleaved) format. Is there anyway to convert this to RGB in real-time using Virtualdub, so I could apply filtering effects on a live video stream?
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| fccHandler |
| Posted: Oct 28 2002, 03:21 PM |
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Administrator n00b
Group: Moderators
Posts: 3961
Member No.: 280
Joined: 13-September 02
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My All-In-Wonder doesn't do RGB, but I've been able to use real-time filtering during capture when I force my capture format to YUY2 (don't ask me how that works, but it does)!
Nevertheless, real-time filtering and audio compression overload the CPU and that's probably why you are getting dropped frames. I recommend that you capture to Huffyuv and uncompressed PCM audio, then do all of your filtering and compression afterwards, for best results.
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May the FOURCC be with you... |
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| dangorn |
| Posted: Oct 28 2002, 05:22 PM |
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| QUOTE (fccHandler @ Oct 28 2002, 09:21 AM) | My All-In-Wonder doesn't do RGB, but I've been able to use real-time filtering during capture when I force my capture format to YUY2 (don't ask me how that works, but it does)!
Nevertheless, real-time filtering and audio compression overload the CPU and that's probably why you are getting dropped frames. I recommend that you capture to Huffyuv and uncompressed PCM audio, then do all of your filtering and compression afterwards, for best results. |
I'm not doing real-time filtering. CPU load isn't the issue--I'm only seeing around 25% CPU load. The problem is more subtle/obscure than overloading my CPU.
YUY2 isn't a supported video format for my card unfortunately. I tried them all, and only one works: UYVY.
And for best quality results, I'd capture with a lossless codec and do all the processor-intensive stuff afterwards, non-realtime. Agreed. But the whole idea of this was a simple digital VCR system. And it is working in that capacity, but it would be nice to chop off a bit of the storage requirements by using a more suitable audio bitrate. 
Thanks for your input,
Dangorn |
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