Cant take an immediate screenshot image of static video from h264 rtp stream

[Nicolas Dufresne]

Le 2014-09-18 09:34, anno domini a écrit :
> gst-launch -v -e v4l2src device=/dev/video1 norm=PAL ! videoscale ! 
> video/x-raw-rgb, width=720, height=576, pixel-aspect-ratio=1/1 ! 
> ffmpegcolorspace ! tee name=videoTee \
> videoTee. ! queue ! x264enc tune="zerolatency" threads=1 
> intra-refresh=true ! rtph264pay config-interval=2 ! udpsink port=8554

You may want to switch from intra-refresh toward periodic keyframe. The 
decoder is simply waiting until a full valid frame is available. Note 
this behaviour may have change if you move toward a recent GStreamer 
(you are using 0.10, which is unmaintained), you would endup with 
corrupted frame in your PNG (see avdec_h264 property output-corrupt). 
Also, note that the general valve approach is racy, and prevent you from 
taking a shot at a specific time since your decoder state is left 
undefined. Assuming you are always previewing this stream, you could set 
"enable-last-sample" on your display sink, and get the last-sample. On a 
second pipeline, using appsink, you could set the sample caps, push the 
buffer, send EOS, and you'd have a safe result instantly.

Nicolas