ProRes - Color Tag Mismatch

[Selur]

For the input ffmpeg reports:

smpte170m/smpte170m/bt709,

mkvmerge reports:

"color_matrix_coefficients": 6, <> SMTPE170M
        "color_primaries": 6, <> SMTPE170M
        "color_transfer_characteristics": 1, <> ITU-R BT.709

mediainfo reports:

colour_range_Source                      : Container
Color primaries                          : BT.601 NTSC
colour_primaries_Source                  : Container
Transfer characteristics                 : BT.709
transfer_characteristics_Source          : Container
Matrix coefficients                      : BT.601
matrix_coefficients_Source               : Container
coder_type                               : Range Coder

Hybrid assumed:
ColorMatrix: bt601 <> smtpe170M <> bt470m <= here is the problem, somewhere it's assumed that these are identical

"C:\Users\redacted\Documents\Programs\Hybrid\64bit\ffmpeg.exe" -y -noautorotate -nostdin -threads 8 -color_primaries bt470m -color_trc bt709 -colorspace bt470bg -color_range tv -f yuv4mpegpipe -i - -an -sn -color_primaries bt470m -color_trc bt709 -colorspace bt470bg -color_range tv -pix_fmt yuv422p10le -strict -1 -fps_mode auto -r 30000/1001 -vcodec prores_ks -profile:v 3 -vtag apch -bsf:v prores_metadata=color_primaries=smpte170m:color_trc=bt709:colorspace=smpte170m -metadata encoding_tool="Hybrid 2025.11.22.1" -aspect 20:15 -f mov "C:\Users\redacted\AppData\Local\Temp\2011177-1-1-pass3_1_2025-12-03@13_14_16_6310_03.mov"

"-bsf:v ..." sets the tags in the stream.
"-color_primaries bt470m -color_trc bt709 -colorspace bt470bg" sets the tags on the container.

Following what you posted, MediaInfo reports fpr the result:

colour_primaries_Original         : BT.601 NTSC
matrix_coefficients_Original      : BT.601

for the stream

Color primaries                        : BT.470 System M
Matrix coefficients                    : BT.470 System B/G

for the container
and

Transfer characteristics             : BT.709

for both the stream and the container. ('original' is only mentioned if stream and container differ)

I'll try to some testing over the weekend. Not sure how I will handle it.

Cu Selur

ps.: if you can share a small sample of the source that would help to reproduce and trying to fix the problem.