Can't mux stereo H.264 to qtmux
@thaytan
Submitted by Jan Schmidt Link to original bug (#752816)
Description
There's a disconnect between h264parse and qtmux when it comes to handling stereoscopic/multiview H.264.
Initially, h264parse outputs caps with video/x-h264...profile=high. Later, when it sees the Subset-SPS packet and knows it is handling stereo or multiview content, it changes the caps.
However, at that point qtmux does:
0:00:00.296990888 19789 0x7fb0000025e0 WARN qtmux gstqtmux.c:4052:gst_qt_mux_video_sink_set_caps:<mp4mux0>
pad video_0 refused renegotiation to video/x-h264, stream-format=(string)avc, alignment=(string)au, width=(int)1280, height=(int)720, pixel-aspect-ratio=(fraction)1/1, framerate=(fraction)10000000/333667, multiview-mode=(string)frame-by-frame, multiview-flags=(GstVideoMultiviewFlagsSet)0:ffffffff:/right-view-first/left-flipped/left-flopped/right-flipped/right-flopped/half-aspect/mixed-mono, parsed=(boolean)true, profile=(string)stereo-high, level=(string)3.1, codec_data=(buffer)0180001fffe200196764001fac56805005b3ff0001000110005176301312d0094000156f80001f4b15a014016cffc000400040abf8fc2a4402000468ce3c8000046848e3c8
and everything halts.
I'm not sure how it should be resolved. It might be possible to make qtmux allow caps changes until some data has been muxed, and refuse after. It's likely more difficult to make h264parse delay the caps setting until later "just in case" a subset SPS comes along.