Videodecoder PTS&DTS question

[Carlos Rafael Giani]

Hello,

I have noticed that when a frame with valid dts but no valid pts is 
pushed downstream with the video decoder finish_frame() call, the 
videodecoder class will internally reuse the DTS of the *last* frame for 
the PTS. As seen here: 
http://cgit.freedesktop.org/gstreamer/gst-plugins-base/tree/gst-libs/gst/video/gstvideodecoder.c#n2406

I wonder why it is not using the DTS of the current frame. I have a test 
video here, with MPEG-4 part 2 encoded data, in an AVI container. 
Keyframes have valid PTS, the rest doesn't. The video shows a circle 
moving steadily and slowly over the screen. Result: at the keyframes, 
the circle "jumps" - playback is not smooth. By checking the PTS prior 
to finishing, and using PTS = DTS , the jumps go away.

However, I am not sure doing this check is a good idea in general. Maybe 
this is actually covering a bug in the AVI demuxer for example? Opinions?