openCV VideoCapture doesn't work with gstreamer x264 -

openCV VideoCapture doesn't work with gstreamer x264 -

i'd display rtp / vp8 video stream comes gstreamer, in opencv.

i have working solution implemented :

gst-launch-0.10 udpsrc port=6666 ! "application/x-rtp,media=(string)video,clock-rate=(int)90000,encoding-name=(string)vp8-draft-ietf-01,payload=(int)120" ! rtpvp8depay ! vp8dec ! ffmpegcolorspace ! ffenc_mpeg4 ! filesink location=videostream

basically grabs incoming info udp socket, depacketize rtp, decode vp8, pass ffmpegcolorspace (i still don't understand for, see everywhere in gstreamer).

the videostream pipe created mkfifo. on side, have opencv code :

videocapture cap("videostream");

and uses cap.read() force mat.

my main concern utilize ffenc_mpeg4 here , believe alters video quality. tried using x264enc in place of ffenc_mpeg4 have no output : opencv doesn't react, neither gstreamer, , after couple of seconds, gst-launch stops.

any thought utilize instead of ffenc_mpeg4 ? looked "lossless codec" on net, seems confusing things such codec, contains, format, compression , encoding ; help (greatly) appreciated !

thanks in advance !

opencv gstreamer h.264 x264 mpeg-4