On Fri, Jul 24, 2015 at 03:28:22PM +0300, Ivan Uskov wrote: > Hello Hendrik, > > Friday, July 24, 2015, 2:37:11 PM, you wrote: > >> The attached patch solves this issue. The corresponded code was taken > >> from \libavcodec\crystalhd.c which also uses the h264_mp4toannexb_bsf > >> filter. > > HL> I don't think this is safe. avctx->extradata is user-managed and > HL> allocated, so mocking with it from within a decoder seems rather > HL> unsafe. > I totally agree. In general it is issue of old-old h264_mp4toannexb_bsf.c > which kills original extradata and silently replaces it by own > version, with annex-b prefixes. Most fanny fact that this filter > can not handle correctly own extradata changes if it creates second > time for the same context. > > I can not patch h264_mp4toannexb_bsf because here can be side effects > in other codecs which can wait replaced extradata (SPS/PPS transformed > to annex-b kind) after this filter work. > Please note that dirty trick with original extradata storing/restoring > does present currently in another codecs which use h264_mp4toannexb_bsf.c. > it is libavcodec\crystalhd.c and libavcodec\libstagefright.cpp, > > I can not left libavcodec/qsvdec_h264.c as is because it is not able > to decode mp4 and mkv at all which is definitely bug. > > Do you have any constructive idea how bad behavior of the > h264_mp4toannexb_bsf.c can be overcome into the libavcodec/qsvdec_h264.c? > Should I write own "good" mp4toannexb filter? > Any other ideas?
it should be possible to add a parameter (passed through args) which disables extradata mangling to h264_mp4toannexb_bsf [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Awnsering whenever a program halts or runs forever is On a turing machine, in general impossible (turings halting problem). On any real computer, always possible as a real computer has a finite number of states N, and will either halt in less than N cycles or never halt.
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