Hello I've a MPEG-4 stream that has the code 00 00 within slice data. I see a slight distortion when I try to decode this using HWAccel VAAPI. I've found that the slice size being fed to VA is wrong.
001aca0: 60c8 b7d4 d755 6eb6 66a0 c082 fff8 283a `....Un.f.....(: 001acb0: a7f9 8a7f 8b6d 3c0a 0f2d 9765 b2c6 672a .....m<..-.e..g* 001acc0: 1703 0000 d626 6159 f0c0 3bb4 402f fea0 .....&aY..;.@/.. 001acd0: 875f d29f fb00 0001 b65a 5998 0ca7 864e ._.......ZY....N 001ace0: 7393 5739 ce4a 5739 cfa5 c9e0 c9c9 9dce s.W9.JW9........ The code in ff_h263_find_resync_marker (ituh263dec.c) in ffmpeg libavcodec returns the position in slice where this code appears and as a result, the slice size being sent to VAAPI is 90B instead of 91E. Commenting this code would get rid of the error. My question is: 1. Would this stream comply with the standard? I tried looking in the standard but didn't find anything related to start code emulation prevention. Does MPEG-4 standard allow start code to be present in the slice data? 2. How should I deal with this? I can see that resync_marker is 0 (resync not enabled) for this stream. Does it make more sense checking specifically for the length of the video packet start code based on vop_coding_type, vop_fcode_forward and vop_fcode_backward parameters? Thank you Anuj _______________________________________________ Libva mailing list Libva@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/libva
