Archived from groups: rec.video.desktop (More info?)
Using AV_IO, I can capture large video streams all day and never drop
a frame. But if I also capture the audio stream, I drop frames at a
small but consistent rate. It has nothing to do with the hard drive
keeping up: I can reduce the video stream to a tiny postage stamp (80
x 60) with a miniscule file size but it still happens. Even stranger,
the problem gets worse if I REDUCE the size of the audio stream. For
instance, if I reduce the audio sampling rate to the lowest setting
(8K mono), AV_IO drops more frames than when the audio sampling rate
is at 44.1K stereo.
The rate of dropped frame is not terrible (about one dropped frame
every 300 at a low audio capture rate, and about one dropped frame
every thousand at a high audio capture rate), but the phenomenon is
completely consistent and 100% reproduceable. It's like an
interference pattern or something -- periodically some combination of
events occurs that AV_IO can't handle and it seems to have nothing to
do with system resources. What could it be?
If anyone would like to know the particulars of the setup: Intel P4
3.2 GHz Northwood core; 800 Mhz FSB; 1 Gig DDR; 120 Gig hard drive for
OS and apps; dedicated 250 Gig hard drive for capture (completely
defragged and empty); Windows 2000; Winnov Videum capture card (and if
I capture with the Videum software instead of AV_IO the problem does
NOT occur, but then I run in to the 2 Gig filesize limit).
Nat Kane
Using AV_IO, I can capture large video streams all day and never drop
a frame. But if I also capture the audio stream, I drop frames at a
small but consistent rate. It has nothing to do with the hard drive
keeping up: I can reduce the video stream to a tiny postage stamp (80
x 60) with a miniscule file size but it still happens. Even stranger,
the problem gets worse if I REDUCE the size of the audio stream. For
instance, if I reduce the audio sampling rate to the lowest setting
(8K mono), AV_IO drops more frames than when the audio sampling rate
is at 44.1K stereo.
The rate of dropped frame is not terrible (about one dropped frame
every 300 at a low audio capture rate, and about one dropped frame
every thousand at a high audio capture rate), but the phenomenon is
completely consistent and 100% reproduceable. It's like an
interference pattern or something -- periodically some combination of
events occurs that AV_IO can't handle and it seems to have nothing to
do with system resources. What could it be?
If anyone would like to know the particulars of the setup: Intel P4
3.2 GHz Northwood core; 800 Mhz FSB; 1 Gig DDR; 120 Gig hard drive for
OS and apps; dedicated 250 Gig hard drive for capture (completely
defragged and empty); Windows 2000; Winnov Videum capture card (and if
I capture with the Videum software instead of AV_IO the problem does
NOT occur, but then I run in to the 2 Gig filesize limit).
Nat Kane
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