Video Frame-rate Weirdness

NewbieToobie

102

« on: 31 / January / 2009, 00:00:57 »

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Earlier today I was watching some deer and squirrels feeding together in the yard. It's been ages since I pushed the video button on my camera. But now I thought I might catch something entertaining. Trouble is, when I reviewed the video tonight I noticed that the speed of the playback was WAY off. The audio recorded at the right rate during playback, I think. It's just the TV playing in the background, shot video through a window, so I can't tell from actions in the video of they are the same rate, but the speed of the animals was going too fast. It's like they were moving at about 1.3x to 1.5x times normal speed.

My camera settings when taking the video were for 640x480, 30fps

I put the video through Virtualdub to change the frame-rate to various speeds. 15 fps was too slow, 23fps was a bit too fast, 20 fps was just about right.

I'm using an S3IS, with CHDK build 0.9.3-0690

I have my CHDK video options set to:

Video Mode: Bitrate
Video Bitrate: 0.75x
Video Quality: 45
Fast Video Control: ON
Video Quality Control: ON
Show Time: BOTH
Refresh Rate: 3 sec

Audio had been left set to 11.025kHz long ago for some reason. It would be nice to see that displayed in the viewfinder so I would know to change it.

Is there some bug in CHDK in this particular build with this camera model that is causing this? Can anyone duplicate this? If so, can this be exploited to give new frame-rates to everyone?

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PhyrePhoX

2254
make RAW not WAR

Re: Video Frame-rate Weirdness

« Reply #1 on: 31 / January / 2009, 00:03:09 »

uhm, what the F? please rephrase this, i cant really make sense of it. hm. seriously. what _exactly_ is the problem here?

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robocat

33

Re: Video Frame-rate Weirdness

« Reply #2 on: 01 / February / 2009, 22:08:31 »

The AVI files produced by canon cameras can be resource hogs on your computer, and will stutter or go slow on a slow CPU and/or old graphics card, or if you try to run them directly from the SD card. This could also occur if you have other resource issues on your machine that is making it go slow.

If this is the problem:
1) Convert the file from an avi to a more efficient format such as wmv and see if the problem goes away.
2) Generally I have seen the sound go at full speed and the video going slower for this problem.

Note that I have seen this issue with 1280x720 video from a TX-1, but I am sure the same principle applies to 640x480 too if the resources are constrained enough.

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