Le dimanche 15 mai 2016 à 13:59 +0200, Peter Maersk-Moller a écrit :
Hi.
What is the recommended module for streaming from a H264 capable UVC webcam? Apparently these days both uvch264src and v4l2src can fetch a stream from a UVC webcam. Earlier there have been mentioning about uvch264src wasn't maintained so much. Is that still the case or is that just outdated talk?
uvch264src is a wrapper around v4l2src that implements the part that are specific to UVC driver. uvch264src will call specific UVC ioctl() and also will demux the resulting jpeg file that combines the preview and the encoded stream.
While uvch264src has parameter options to set minimum-bitrate, maximum-bitrate and average-bitrate, the v4l2src does not. Using the caps like show here below does not seem to influence the bitrate:
$ h264caps="video/x-h264,alignment=(string)au,width=(int)1280,height=(int)720,framerate=(fraction)30/1,profile=(string)main,minimum-bitrate=(uint)2000000,maximum-bitrate=(uint)2500000,bitrate=(uint)2200000"
Indeed, this is not exposed through V4L2 ioctl. It's not valid caps either.
$ gst-launch-1.0 -v v4l2src ! $h264caps ! ....
while parameter options with uvch264src works:
$ gst-launch-1.0 uvch264src initial-bitrate=2500000 \
average-bitrate=2200000 peak-bitrate=2500000 \
minimum-bitrate=2000000 fixed-framerate=true \
iframe-period=2000 device=/dev/video0 name=src \
auto-start=true do-timestamp=true src.vidsrc ! ...
Thanks in advance
Peter
hope this information is useful to you,
Nicolas
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