Hello Michael,
Sunday, July 24, 2016, 11:25:29 PM, you wrote:
MN> On Sun, Jul 24, 2016 at 11:18:38PM +0300, Ivan Uskov wrote:
>> Hello Michael,
>>
>> Sunday, July 24, 2016, 11:11:32 PM, you wrote:
>>
>> MN> On Sun, Jul 24, 2016 at 09:55:21PM +0300, Ivan Uskov wrote:
>> >> Hello All,
>> >>
>> >> I have discovered the following issue:
>> >> Latest builds of ffmpeg crashes into the h264.c when *hardware* qsv-based
>> >> h264 decoder uses.
>> >> The crash does appear inside the
>> >>
>> >> int avpriv_h264_has_num_reorder_frames(AVCodecContext *avctx)
>> >> {
>> >> H264Context *h = avctx->priv_data;
>> >> return h && h->ps.sps ? h->ps.sps->num_reorder_frames : 0;
>> >> }
>> >>
>> >> It is obvious, that casting to H264Context cannot be used for qsv decoder
>> >> because there is QSVH2645Context. Similar issue will appear for CUVID
>> >> decoder case (CuvidContext uses), Android MediaCodec H.264 decoder
>> >> (MediaCodecH264DecContext uses), possible another cases existing.
>> >>
>> >> The caller function is
>> >>
>> >> static int has_decode_delay_been_guessed(AVStream *st)
>> >> {
>> >> if (st->codecpar->codec_id != AV_CODEC_ID_H264) return 1;
>> >> if (!st->info) // if we have left find_stream_info then
>> >> nb_decoded_frames won't increase anymore for stream copy
>> >> return 1;
>> >> #if CONFIG_H264_DECODER
>> >> if (st->internal->avctx->has_b_frames &&
>> >> avpriv_h264_has_num_reorder_frames(st->internal->avctx) ==
>> >> st->internal->avctx->has_b_frames)
>> >> return 1;
>> >> #endif
>> >> if (st->internal->avctx->has_b_frames<3)
>> >> return st->nb_decoded_frames >= 7;
>> >> else if (st->internal->avctx->has_b_frames<4)
>> >> return st->nb_decoded_frames >= 18;
>> >> else
>> >> return st->nb_decoded_frames >= 20;
>> >> }
>> >> ...which called by update_initial_timestamps()
>> >>
>> >> Have anybody the idea how it can be correctly fixed?
>> >> Looks like has_decode_delay_been_guessed() should be corrected.
>>
>> MN> this code is not new, this is in git since 4 years
>> MN> commit bafa1c7f383d6c1c0f3d207395fe6a574092b7ac
>> MN> Date: Mon Jul 2 23:16:59 2012 +020
>>
>> MN> why does it cause a problem now ?
>>
>> MN> why does libavformat use hw h264 decoding ?
>> I do not know that is reason why I'm asking.
>> I just run ffmpeg like
>> ffmpeg -c:v h264_qsv -i ./Ducks.Take.Off.720p.QHD.CRF24.x264-CtrlHD.mkv
>> -vcodec h264_qsv -y ./result.mp4
>> ..and it crashes inside avpriv_h264_has_num_reorder_frames(AVCodecContext
>> *avctx)
>>
>> When I replace
>> #if CONFIG_H264_DECODER
>> to
>> #if 0
>> ...all working fine.
>>
>> I can not say when exactly the issue appeared, about several weeks ago all
>> worked correct. But current build is broken at this place.
MN> can you use git bisect to figure out when this issue appeared?
Ok, I'll try, it will take some time.
MN> was the decoder used in libavformat previously also the hw instead of
MN> sw decoder ?
There are no appropriate methods in hw decoder to be called from libavformat.
So hw decoder exactly was never used.
MN> [...]
--
Best regards,
Ivan mailto:ivan.us...@nablet.com
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
