Hi Carles, > On Feb 11, 2015, at 1:45 PM, Carles Vila <cvi...@gmail.com> wrote: > > Hi all, > I'd like to set up a command to find out if a video is broadcast legal. > I've tried to understand how signalstats works but I need some help. > I tried the examples in the ffmpeg filter documentation, like the one > pasted below, but I'd like to customize it to my needs. > > Ideally It would output a list of frames that do not meet broadcast specs. > > FWIW, the video is Quicktime wrapped DNxHD. > Thank you! > > > $ ffprobe -f lavfi movie=INPUTFILE.mov,signalstats="stat=brng" -show_frames > ffprobe version 2.4.2 Copyright (c) 2007-2014 the FFmpeg developers > built on Oct 28 2014 17:39:46 with Apple LLVM version 5.1 > (clang-503.0.40) (based on LLVM 3.4svn) > configuration: --prefix=/usr/local/Cellar/ffmpeg/2.4.2 --enable-shared > --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree > --enable-hardcoded-tables --enable-avresample --enable-vda --cc=clang > --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac > --enable-libmp3lame --enable-libxvid --enable-libfreetype > --enable-libtheora --enable-libvorbis --enable-libvpx --enable-librtmp > --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-aacenc > --enable-libass --enable-ffplay --enable-libspeex --enable-libschroedinger > --enable-libfdk-aac --enable-libopus --enable-frei0r --enable-libopenjpeg > --extra-cflags='-I/usr/local/Cellar/openjpeg/1.5.1_1/include/openjpeg-1.5 ' > libavutil 54. 7.100 / 54. 7.100 > libavcodec 56. 1.100 / 56. 1.100 > libavformat 56. 4.101 / 56. 4.101 > libavdevice 56. 0.100 / 56. 0.100 > libavfilter 5. 1.100 / 5. 1.100 > libavresample 2. 1. 0 / 2. 1. 0 > libswscale 3. 0.100 / 3. 0.100 > libswresample 1. 1.100 / 1. 1.100 > libpostproc 53. 0.100 / 53. 0.100 > Input #0, lavfi, from 'movie=INPUTFILE.mov,signalstats=stat=brng': > Duration: N/A, start: 0.000000, bitrate: N/A > Stream #0:0: Video: rawvideo (Y42B / 0x42323459), yuv422p, 1920x1080 > [SAR 1:1 DAR 16:9], 25 tbr, 25 tbn, 25 tbc > [FRAME] > media_type=video > key_frame=1 > pkt_pts=0 > pkt_pts_time=0.000000 > pkt_dts=0 > pkt_dts_time=0.000000 > best_effort_timestamp=0 > best_effort_timestamp_time=0.000000 > pkt_duration=1 > pkt_duration_time=0.040000 > pkt_pos=577024 > pkt_size=4147200 > width=1920 > height=1080 > pix_fmt=yuv422p > sample_aspect_ratio=1:1 > pict_type=I > coded_picture_number=0 > display_picture_number=0 > interlaced_frame=0 > top_field_first=0 > repeat_pict=0 > TAG:lavfi.signalstats.YMIN=12 > TAG:lavfi.signalstats.YLOW=58 > TAG:lavfi.signalstats.YAVG=74.9742 > TAG:lavfi.signalstats.YHIGH=84 > TAG:lavfi.signalstats.YMAX=241 > TAG:lavfi.signalstats.UMIN=36 > TAG:lavfi.signalstats.ULOW=145 > TAG:lavfi.signalstats.UAVG=150.074 > TAG:lavfi.signalstats.UHIGH=158 > TAG:lavfi.signalstats.UMAX=166 > TAG:lavfi.signalstats.VMIN=47 > TAG:lavfi.signalstats.VLOW=98 > TAG:lavfi.signalstats.VAVG=106.101 > TAG:lavfi.signalstats.VHIGH=112 > TAG:lavfi.signalstats.VMAX=174 > TAG:lavfi.signalstats.SATMIN=0 > TAG:lavfi.signalstats.SATLOW=24 > TAG:lavfi.signalstats.SATAVG=32.6906 > TAG:lavfi.signalstats.SATHIGH=42 > TAG:lavfi.signalstats.SATMAX=99 > TAG:lavfi.signalstats.HUEMED=313 > TAG:lavfi.signalstats.HUEAVG=308.107 > TAG:lavfi.signalstats.YDIF=0 > TAG:lavfi.signalstats.UDIF=0 > TAG:lavfi.signalstats.VDIF=0 > TAG:lavfi.signalstats.BRNG=0.00231144 > [/FRAME]
This means that 0.00231144% of the frame is outside of broadcast range (Y within 16-235 and U/V within 16-240) which in your file is about 4,793 pixels. I vaguely remember someone referring a broadcast standards document which referred to broadcast legal not considering 100% of pixels to be within that range, but considered broadcast legal to mean somewhat less than 100% of the pixels had to be in the stated ranges. Unfortunately I can't remember what amount of outliers was tolerated or what the spec was. The output of ffprobe -f lavfi movie=INPUTFILE.mov,signalstats="stat=brng" -show_entries frame_tags=lavfi.signalstats.BRNG -of flat may be easier to parse in your scenario since the output will include the frame numbers, like frames.frame.567.tags.lavfi_signalstats_BRNG="0" frames.frame.568.tags.lavfi_signalstats_BRNG="0" frames.frame.569.tags.lavfi_signalstats_BRNG="0" then you would need to grep out the lines where BRNG exceed some defined threshold. Hope this helps. Dave Rice _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
