[FFmpeg-user] Use of "-color_range"

[Tim Nicholson]

On 10/07/11 11:10, Thomas Worth wrote:

> Tim, did you ever get this to work properly? I tried transcoding some
> v210 footage to mjpeg, but since mjpeg requires "yuvj" pixel format
> variants, my range is always wrong because the v210 I am working with
> is broadcast range. The mjpeg encoder apparently takes the full range
> as input, so it looks at 0-1023 instead of 64-940.
>

well what I did was take two input png's of colour bars, one full range 
one 601 range and output an uncompressed 8 bit mov using the code below:-

=======================================
for range in 0 1 2
do
out_file=$(basename $1).${range}.mov
ffmpeg -f image2 -loop_input -i $1 -t 5 -vcodec rawvideo -pix_fmt \ 
uyvy422 -color_range $range -vtag 2vuy -an -y "$out_file"


out_file=${range}.$(basename $1).mov
ffmpeg -f image2 -loop_input -color_range $range -i $1 -t 5 -vcodec \ 
rawvideo -pix_fmt uyvy422 -vtag 2vuy -an -y "$out_file"

done
=======================================

As you can see one variation changed the parameter for output, and the 
other version changed it for input.

I then viewed all 6 files in Lightworks (public beta) so I could use the 
scope function.

For any given input file all 6 outputs were identical no matter what the 
setting of -color_range and whether applied to input or output. However 
the differences between the input files was reflected on the outputs.

This would suggest that color_range is having no effect.

*However* I don't know if the "image2" format for input overrides the 
color_range setting, so I want to run some more passes using my 
generated mov's as source.

> What would be great is if I could force ffmpeg / swscale to consider
> only 64-940 as input instead of 0-1023. For most intents and purposes,
> only 64-940 is a valid range with v210.

Absolutely!

-- 
Tim

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