Sounds like you have a good understanding of the nal units and h264 traffic in general. So It might be a decoder issue. I have found descrepencies in interpretations of the standard.
>From experience... Each Nal unit needs a header before it goes to the decoder. This is the 00 00 00 01 before the nal unit. I have seen some streams only have 00 00 01 and different versions of libavcodec for example would be tolerent or not tolerent of this. Assuming [x] represents the nal unit x with the headers. and 7 is sps 8 is pps 5 is IDR slice and 1 is P-slice [7][8][5][1][1][1]...[1][7][8][5][1][1]... is normal [7][8][5][5][5][1][1][1]...[1][7][8][5][5][5][1][1]... is seen on high resolution [7][8][5][1][1][1]...[1][5][1][1]... is legal [7][8][5][1][1][1]...[1][7][8][1][1]...[5][1][1].... is actually legal per standard but messes with some decoders. On Thu, Feb 13, 2014 at 9:13 AM, Eli <el...@bdrgroup.com> wrote: > Hi everyone, > > > > I have encountered a strange problem while playing an RTP H.264 stream > using VLC player. > > > > I am developing firmware for an IP camera designed to be used with > specialized software (control client). > > By default, the camera's RTSP streamer (based on wis-streamer with a > custom video source) had a bug where in each GOP, the SPS, PPS, SEI and > IDR-frame were all grouped, and the stream simply consisted of an SPS NAL > unit, followed by several P-slices. The PPS, SEI, and IDR-frame were all > hidden inside the payload of the SPS packet. This caused the target > software to be unable to play the stream, yet VLC player worked just fine. > > > > After fixing the video source and properly splitting the various NAL > units, the stream works properly on the target client, but now it works > only partially with VLC - sometimes it works well, other times it freezes > after showing 1-2 frames. Looking at the wireshark capture, the stream now > looks like a proper H.264 stream: SPS, PPS, SEI, IDR, P-Slice, P-Slice, > P-Slice... > > I've uploaded wireshark logs and VLC logs for both scenarios (old stream, > new stream): > > > > https://www.dropbox.com/s/kk4m04toudijb82/new.log > > https://www.dropbox.com/s/gyg39osmhqi7p1r/New.pcapng > > > > https://www.dropbox.com/s/ewank7m3itt8jcr/old.log > > https://www.dropbox.com/s/jk08a4nq8cuog76/Old.pcapng > > > I've posted this question to the VLC support boards and was advised it > might be a live555 problem and that I should ask about it over here. > > Any help would be greatly appreciated. > > _______________________________________________ > live-devel mailing list > live-devel@lists.live555.com > http://lists.live555.com/mailman/listinfo/live-devel > >
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