On Fri, Jan 24, 2025 at 3:59 AM Zhao Zhili <quinkblack-at-foxmail....@ffmpeg.org> wrote: > > > > > On Jan 24, 2025, at 02:02, Timo Rothenpieler <t...@rothenpieler.org> wrote: > > > > On 23.01.2025 15:17, Zhao Zhili wrote: > >> From: Zhao Zhili <zhiliz...@tencent.com> > >> Otherwise all frames can be dropped after seek without the > >> output_corrupt/showall flags. > >> --- > >> libavcodec/nvenc.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> diff --git a/libavcodec/nvenc.c b/libavcodec/nvenc.c > >> index 06e3fb81a4..68b1b661e4 100644 > >> --- a/libavcodec/nvenc.c > >> +++ b/libavcodec/nvenc.c > >> @@ -1247,6 +1247,7 @@ static av_cold int > >> nvenc_setup_h264_config(AVCodecContext *avctx) > >> h264->intraRefreshPeriod = cc->gopLength; > >> h264->intraRefreshCnt = cc->gopLength - 1; > >> cc->gopLength = NVENC_INFINITE_GOPLENGTH; > >> + h264->outputRecoveryPointSEI = 1; > >> #ifdef NVENC_HAVE_SINGLE_SLICE_INTRA_REFRESH > >> h264->singleSliceIntraRefresh = ctx->single_slice_intra_refresh; > >> #endif > >> @@ -1380,6 +1381,7 @@ static av_cold int > >> nvenc_setup_hevc_config(AVCodecContext *avctx) > >> hevc->intraRefreshPeriod = cc->gopLength; > >> hevc->intraRefreshCnt = cc->gopLength - 1; > >> cc->gopLength = NVENC_INFINITE_GOPLENGTH; > >> + hevc->outputRecoveryPointSEI = 1; > >> #ifdef NVENC_HAVE_SINGLE_SLICE_INTRA_REFRESH > >> hevc->singleSliceIntraRefresh = ctx->single_slice_intra_refresh; > >> #endif > > > > Is there any reason someone might not want this? > > Or could it break certain scenarios? > > Reads to me like it'd only make the bitstream slightly larger, or are there > > other implications? > > For H.264 and H.265, GDR is intra refresh encoding together with recovery > point SEI. SEI is optional for > decoding, but it’s critical for GDR decoding. For H.266, GDR is a NALU type, > which makes this > technique complete. > > Without recovery point SEI, we can try decoding at any point blindly by > specify -flags output_corrupt, > which isn’t the default behavior of our decoder. Otherwise all frames can be > dropped and > never recovery. > > x264 don’t make option to disable recovery point SEI, which I think is the > right design. > On the other hand, both x265 and hevc_nvenc don’t output recovery point SEI > or output > recovery point SEI with useless fields, which makes user who want to use > intra refresh > encoding must specify -flags output_corrupt for decoding. That is, without > recovery point > SEI, user should have prior knowledge on encoding configuration before > decoding. > > Anyway, even incorrect recovery point SEI is helpful so we don’t need to > specify -flags > output_corrupt manually. Follow x264’s design, I don’t think save a few bytes > worth the > trouble of disable recovery point SEI.
I don't know anything about nvenc specifically, but I think this decision about recovery point SEI is correct. Kieran _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
