[SOLVED] Need UVC webcam to produce 30 fps

Dafydd · 01-14-2011, 10:40 PM

Logitech 9000 pro.

I need 30 fps so I can splice into existing video.
I am using this script.

Code:

#!/bin/bash
##Turn on webcam and save video and audio output to file.

# check if there is no command line argument
if [ $# -eq 0 ]
then
echo "You forgot to name the output file!"
echo "Usage :: webcam-capture name of output file"
exit
fi

name=$1;


mencoder -tv fps=30:driver=v4l2:buffersize=256:norm=NTSC:input=0:volume=40:amode=1:quality=100:width=640:height=480:device=/dev/video0:adevice=/dev/dsp1:audiorate=44100:immediatemode=0:forceaudio tv:// -o "$name".avi -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=490:keyint=18 -ofps 30 -vf lavcdeint -oac mp3lame -lameopts cbr:br=96:mode=0 -noskip


echo "Recording. Ctrl-C or close window to stop"

Even though I have set 'fps' to 30, I only get between 14 and 16. Several thread on the internet tell me that UVC in only capable of 15 fps in 640x480 mode.

Is there some way to make the camera (ID 046d:0809 Logitech, Inc.) work as something OTHER than a UVC type camera? Is there a code snippet to work with?

I have no problems with getting the camera to work with any of the apps in the Ubuntu reposit. The script above records video and audio great, just not 30 fps.

TIA
Dave

PS
The video I will be splicing into will be shot with a video recorder and windows software. If it is a USB hookup, will it have the same constraints of UVC at 15 fps. IIRC, it is the USB that has the compression problem that limit it to 15 fps.

Dafydd · 01-17-2011, 07:56 PM

Further search and read has led me to the reason for the low FPS on the webcam. Everything states that the UVC is capible of 30 fps. What it doesn't tell you is that the fps speed is determined by the exposure.

The less light the longer it takes the camera to correct and compress the image. The solution is to turn off automatic exposure. That can drastically affect image quality, but it does speed up fps.

Lets mark this solved for a while.