On 12 February 2015 at 02:17, Dave Rice <d...@dericed.com> wrote: > 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 >
Hi Dave, thanks so much for the explanation and the command. I look forward to test it out. I found this document: http://www.bbc.co.uk/guidelines/dq/pdf/tv/TechnicalDeliveryStandardsBBCv3.pdf where it states: 2.3.2 Tolerance of out of gamut signals In practice it is difficult to avoid generating signals slightly outside this range, and it is considered reasonable to allow a small tolerance, which has been defined as follows under EBU Rec103: RGB components must be between -5 % and 105% (-35 and 735mV) and Luminance (Y) must be between -1% and 103% (-7mV and 721mV) Slight transient overshoots and undershoots may be filtered out before measuring, and an error will only be registered where the out of gamut signals total at least 1% of picture area. Many monitoring devices are designed to detect errors to this specification. - _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user