Hi Alex, > On Jan 23, 2015, at 10:23 AM, Alex Kink <alexk...@gmail.com> wrote: > > Hello all. > > Is there a way to detect blue screen (usually generated by analog videotape > equipment) using ffmpeg. I know there is a way to detect black screen. > > Below is a sample of what I have in mind. > > https://www.youtube.com/watch?v=fC_bO-4uwFk
You could use the metadata output of the signalstats filter to get the average hue (HUEAVG), like this: ffprobe -f lavfi movie=AnalogVideoToBlueScreen5seconds-fC_bO-4uwFk.mp4,signalstats -show_entries frame_tags=lavfi.signalstats.HUEAVG -of flat The HUEAVG value for a blue frame is 279, so finding frames where HUEAVG equals 279 +/- some margin would find frames are blue. If looking for a specific saturation of blue you could use the average values of the chroma plans (UAVG and VAVG), which could be accessed like this: ffprobe -f lavfi movie=AnalogVideoToBlueScreen5seconds-fC_bO-4uwFk.mp4,signalstats -show_entries frame_tags=lavfi.signalstats.UAVG,lavfi.signalstats.VAVG -of flat The specific blue is your video is roughly UAVG=205 and VAVG=114, so finding frames close to those values would give you the blue frames you're looking for. Another option could be using the geq filter with if statements which would replace U and V values with black if in those numerical ranges, then adding blackdetect next in the filterchain. Dave Rice _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
