[FFmpeg-user] a -vf for broadcast safe

[Paul B Mahol]

On 12/30/15, Dave Rice <dave at dericed.com> wrote:
>
>> On Feb 12, 2014, at 4:43 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
>>
>> Jim Shupert <jshupert <at> pps-inc.com> writes:
>>
>>> input a unCompressed  yuv avi and get a second
>>> Uncompressed yuv avi or mov and it would be
>>> 'broadcast safe'.
>>
>> Rereading your original post:
>> Could you provide an uncompressed yuv avi that
>> needs the filter you have in mind?
>> (One frame is probably enough.)
>
> Responding late, as I find myself in need of this filter as well.
>
> A sample that needs the filter can be generated via:
>
> ffmpeg -f lavfi -i color=gray:s=256x256 -vf
> format=yuv444p,geq=lum=X,scale=out_range=tv -vframes 1 -pix_fmt yuv444p -c:v
> rawvideo -y needsbroadcastsafe.nut
> ffmpeg version 2.8.4 Copyright (c) 2000-2015 the FFmpeg developers
>   built with Apple LLVM version 7.0.2 (clang-700.1.81)
>   configuration: --prefix=/usr/local/Cellar/ffmpeg/2.8.4 --enable-shared
> --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables
> --enable-avresample --cc=clang --host-cflags= --host-ldflags=
> --enable-opencl --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc
> --enable-libxvid --enable-libfreetype --enable-libfaac --enable-libass
> --enable-ffplay --enable-libopenjpeg --disable-decoder=jpeg2000
> --extra-cflags=-I/usr/local/Cellar/openjpeg/1.5.2_1/include/openjpeg-1.5
> --enable-nonfree --enable-vda
>   libavutil      54. 31.100 / 54. 31.100
>   libavcodec     56. 60.100 / 56. 60.100
>   libavformat    56. 40.101 / 56. 40.101
>   libavdevice    56.  4.100 / 56.  4.100
>   libavfilter     5. 40.101 /  5. 40.101
>   libavresample   2.  1.  0 /  2.  1.  0
>   libswscale      3.  1.101 /  3.  1.101
>   libswresample   1.  2.101 /  1.  2.101
>   libpostproc    53.  3.100 / 53.  3.100
> Input #0, lavfi, from 'color=gray:s=256x256':
>   Duration: N/A, start: 0.000000, bitrate: N/A
>     Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 256x256 [SAR
> 1:1 DAR 1:1], 25 tbr, 25 tbn, 25 tbc
> Output #0, nut, to 'needsbroadcastsafe.nut':
>   Metadata:
>     encoder         : Lavf56.40.101
>     Stream #0:0: Video: rawvideo (444P / 0x50343434), yuv444p, 256x256 [SAR
> 1:1 DAR 1:1], q=2-31, 200 kb/s, 25 fps, 51200 tbn, 25 tbc
>     Metadata:
>       encoder         : Lavc56.60.100 rawvideo
> Stream mapping:
>   Stream #0:0 -> #0:0 (rawvideo (native) -> rawvideo (native))
> Press [q] to stop, [?] for help
> frame=    1 fps=0.0 q=-0.0 Lsize=     192kB time=00:00:00.04
> bitrate=39382.2kbits/s
> video:192kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
> muxing overhead: 0.154114%
>
> The result of `ffmpeg -i needsbroadcastsafe.nut -vf broadcastsafe
> nowbroadcastsafe.nut` would result in the output containing luma values only
> between 16-235 inclusively (8 bit) and 16-240 for chroma planes.

So what it would do? Rescale everything with fixed number, just clip,
or some other
fancy stuff?
IMHO this is scale bug, does same happens with zscale?