чт, 11 янв. 2024 г., 03:13 Andrew Randrianasulu <randrianas...@gmail.com>:
> I was looking at videohelp forum > > > https://web.archive.org/web/20201125203546/https://forum.videohelp.com/threads/398119-Cutting-Open-GOP-H264-videos-properly > > (web archive link because it hopefully will stay active for some time even > if forum software will be upgraded and ruin old links in the future) > > It provides this ffprobe-based method of seeing if given h264 video stream > is Open GOP or not : > > echo entry,pkt_pts_time,pict_type,coded_picture_number > "%~n1.csv" > > ffprobe -v 32 -stats -y -hide_banner -i %1 -select_streams v -print_format > csv -of csv -show_entries > "frame=pkt_pts_time,pict_type,coded_picture_number" >> "%~n1.csv" > > === quote ==== > > You can see that the last frame of the first GOP is a B frame -- so that's > an open GOP. Also, the coded picture number is higher than that of the I > frame after it -- indicating that the I frame had to be decoded before the > B frame, another indication of an open GOP. > > === quote ends === > > I checked one of my videos: > > ffprobe -v 32 -stats -y -hide_banner -i > ~/Sea_of_life_plus_Mikura_dolphins_test.mp4 -select_streams v -print_format > csv -of csv -show_entries > "frame=pkt_pts_time,pict_type,coded_picture_number" >> "Sea_of_life-n1.csv" > > and it seems resulting cvs file show it as open GOP consistently with > mediainfo: > > frame,8.308300,B,250 > frame,8.341667,I,249 > frame,8.375033,B,253 > > mediainfo (v23.11) snip: > > === snip === > > Video > > ID : 1 > > Format : AVC > Format/Info : Advanced Video > Codec > Format profile : High@L4.1 > Format settings : 4 Ref Frames > > Format settings, CABAC : No > Format settings, Reference frames : 4 frames > > Codec ID : avc1 > > Codec ID/Info : Advanced Video Coding > > Duration : 5 min 4 s > Bit rate : 16.0 Mb/s > Width : 1 920 pixels > > Height : 1 080 pixels > > Display aspect ratio : 16:9 > > Frame rate mode : Constant > > Frame rate : 29.970 (30000/1001) FPS > Color space : YUV > > Chroma subsampling : 4:2:0 > > Bit depth : 8 bits > > Scan type : Progressive > > Bits/(Pixel*Frame) : 0.257 > Stream size : 575 MiB (99%) > > Writing library : x264 core 148 > > Encoding settings : cabac=0 / ref=3 / deblock=1:0:0 > / analyse=0x3:0x113 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / > mixed_ref=1 / me_range=16 / chroma_me=0 / trellis=1 / 8x8dct=1 / cqm=0 / > deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=3 / > lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / > bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=0 > / b_bias=0 / direct=1 / weightb=1 / open_gop=1 / weightp=2 / keyint=250 / > keyint_min=25 / scenecut=0 / intra_refresh=0 / rc_lookahead=40 / rc=abr / > mbtree=1 / bitrate=16000 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / > qpstep=4 / ip_ratio=1.41 / aq=1:1.00 > > Codec configuration box : avcC > > ==== snip ends === > > So, at least I may try to cut this video at various intervals and see if > cutting breaks on specifically open-gop h264 stream. > > But as it was said in forum post above - ffprobe a bit slow, few minutes > for whole video, eating one cpu core completely. > > Is there faster way to get this info ? > Additionally, I tried to add another variable key_frame to see difference between IDR frames (I type , key_frame=1) and just I type frames: ffprobe -v 32 -stats -y -hide_banner -i ~/Sea_of_life_plus_Mikura_dolphins_test.mp4 -select_streams v -print_format csv -of csv -show_entries "frame=pkt_pts_time,pict_type,key_frame,coded_picture_number" >> "Sea_of_life-n1-v1.csv" but resulting csv file grouped them like frame,1,8.341667,I,249 like key_frame come before pkt_pts_time. May be this is bug due to ffprobe being from v. 4.4.4 and not latest. Not sure. But interesting. I also see few picture types in libavutil/avutil.h enum AVPictureType { AV_PICTURE_TYPE_NONE = 0, ///< Undefined AV_PICTURE_TYPE_I, ///< Intra AV_PICTURE_TYPE_P, ///< Predicted AV_PICTURE_TYPE_B, ///< Bi-dir predicted AV_PICTURE_TYPE_S, ///< S(GMC)-VOP MPEG-4 AV_PICTURE_TYPE_SI, ///< Switching Intra AV_PICTURE_TYPE_SP, ///< Switching Predicted AV_PICTURE_TYPE_BI, ///< BI type }; Is this list complete when it comes to codecs like HEVC ? _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
