[FFmpeg-user] How can I set in a D10 MXF (IMX50) file the flags for output color_range, -space, -transfer and primaries?

[tim nicholson]

On 30/04/15 22:03, Marton Balint wrote:
> 
> On Wed, 29 Apr 2015, Christoph Gerstbauer wrote:
> 
>> I found out that a IMX50 mxf file encoded with FFmbc and the IMX50 mxf
>> file encoded with actual ffmpeg builds are different in these mxf
>> metadata flags (by reading out via ffprobe - show_streams)

Are you sure you mean specifically "mxf metadata flags"?
See my comments below.

>>
>> FFMBC IMX FILE stream 0:0:
>> color_range=tv
>> color_space=smpte170m
>> color_transfer=bt709
>> color_primaries=bt470bg
>>
>>
>> FFMPEG IMX FILE stream 0:0:
>> color_range=tv
>> color_space=unknown
>> color_transfer=unknown
>> color_primaries=unknown
>>
>> I want to set these metadata flags to the same values, but with FFmpeg.
>> How can I produce the same output like ffmbc with these 4 metadata flags?
>> I didnt found a answer to that in the ffmpeg documentation :/
> 
> You can manually specify these settings to force them being set with
> these parameters:
> 
> -color_primaries 5
> -color_trc 1
> -colorspace 6
> 
> What does not work as far as I know in ffmpeg is to actually get these
> settings from the source video, even if ffprobe detects them.
> 

And what does not work as far as I know in ffmpeg is these values
actually being written by the mxf muxer. At least I cannot find the
relevant UL's listed in the "Generic Picture Essence Descriptor" section
of mxfenc.c which is where I would expect to see them. Or any where else
for that matter.

Nor are they in ffmbc for that matter, so I suspect ffprobe is picking
them up from the essence rather than the specific mxf UL's. (ffmbc sets
the parameters Marton lists as part of the IMX target, which ffmpeg does
not have)

Given that "MXF encoders should encode Transfer Characteristic whenever
possible" smpte S377-1, this is clearly an omission and I am surprised
the IRT analyser doesn't spot it.

Christoph do you actually require the mxf metadata setting (as it really
ought to be, and what I thought you were after) or are you content with
it in the essence, in which case, in the absence of a target preset, you
will have to set the flags yourself.


> Regards,
> Marton
> [..]

-- 
Tim.
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