Greetings,
We use a Sony HCM-CH240 3mpixel camera to capture our data and MPEG4
stream via RTSP to a Linux box (Ubuntu) running openRTSP, -i to pipe
output in *.avi format. The problem is that the camera sends vop (video
object plane) start sequence frame type-- I think in the same RTP packet
payload as an I-frame (I-VOP) type (defining the start of a Group Of
Pictures) We were sent proprietary white papers from Sony describing the
theory of operation of this camera (for developers). Generally a bit
stream of a visual object sequence (e.g., Group Of Pictures) is
terminated with another frame containing a VOP termination code;
but this termination code frame is not added in the case of this camera
(I do not have enough experience with commercial ip cams to understand
if this is the norm or not...)
The camera consistently writes out a vop start of sequence frame in this
manner for *every* GOP sequence. It seems like openRTSP client keeps
*BOTH* the 'empty' start sequence vop frame, *AND*, the I-FRAME, and
actually assigns a time stamp to both?? Then, then for the next frame
received in the payload, the program sees that the timestamp matches
the time stamp of the I-FRAME assigned previously and it is thrown
out to preserve the proper frame rate
Could this be possible??
The result: constant pause-and-skip motions of image sequence. I have
now noticed this with other programs too (for example VLC, etc.). This
has inspired us to try different tricks with mencoder but none of them
will remove the duplicate, vop start-sequence frame--even though
mencoder recognizes the problem! I tried hard-setting framerate and
frame size and it does nothing.
Has anyone encountered a similar problem, and if so, could you share how
you addressed it?
I'm quite a newbie with utilizing openRTSP, and ip cameras for this
purpose.
thanks to all in advance,
t
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