Created attachment 206046 [details]
h264 stream in mp4 container that cannot be parsed properly

Conversion from packetized au aligned avc streams to au aligned byte streams is broken.

* For avc, split_packetized is always set to TRUE with the comment: "if input != output, and input is avc, must split before anything else".
* avc packets are split in gst_h264_parse_chain and NALUs passed separately to baseparse chain
* baseparse chain calls gst_h264_parse_check_valid_frame with one NALU from packet
* check_valid_frame knows that it has a complete NALU and returns success
* NAL collection code is useless when input is packetized. gst_h264_parse_collect_nal doesn't function and its return value is ignored in check_valid_frame.
* baseparse think we have a full frame and pushes it. In reality we have one NALU only.
* pushed "frame" *always* consist of one NALU. Regardless of negotiated alignment (au/nal) we always get nal. src caps is lying which causes downstream elements to fail.

The attached sample triggers these problems:

gst-launch -v filesrc location=output.mp4 ! qtdemux ! h264parse ! video/x-h264,stream-format=byte-stream,alignment=au ! fakesink

* result is nal aligned, not au
* many pushed buffers/nals lacks timestamps
* SPS/PPS from codec_data are injected before first IDR NALU (4th), in the middle of first AU. According to spec, AU delimiter is always first NAL in AU if present. SPS/PPS should go after it, before the two SEIs that reference the SPS/PPS.