Colorimetry Info in H.264 Streams

[ToS_Maverick]

i've read this (http://forum.doom9.org/showthread.php?t=131169) thread about colorimetry in mpeg2. now i'm concerned about h.264:

- what colorspace is used by default?
- is the colorspace-info stored somewhere in the stream?
- are there tools to get the info? (i got hd-streams from sattelite, which are bt.709, i just want to be sure)
- is it possible to implement a switch in x264 to set the colorimetry?

i know, that normally, like xvid for sd bt.601 is used. even CoreAVC interprets my sattelite-footage witch is 709 as 601, which is wrong of course.

[Adub]

Use search.

http://forum.doom9.org/showpost.php?p=1063256&postcount=4

there are a variety of h.264 information programs, i am pretty sure one of them should be able to tell you.

[ToS_Maverick]

well with elecard streameye i got the
color description flag,
color primaries,
transfer caracteristics and the
matrix coefficients.

now i only need to know what they mean!

wouldn't it be better to keep the footage in 709? and why doesn't a decoder respect the flags?

[pandy]

i've read this (http://forum.doom9.org/showthread.php?t=131169)
- what colorspace is used by default?
- is the colorspace-info stored somewhere in the stream?
- are there tools to get the info? (i got hd-streams from sattelite, which are bt.709, i just want to be sure)
- is it possible to implement a switch in x264 to set the colorimetry?

i know, that normally, like xvid for sd bt.601 is used. even CoreAVC interprets my sattelite-footage witch is 709 as 601, which is wrong of course.

many of devices intepret SD as 601, HD as 709, information about color space is in VUI (Annex E of H.264 spec.), accordingly to the x264 HELP info:
--colorprim <string> Specify color primaries ["undef"]
- undef, bt709, bt470m, bt470bg, smpte170m, smpte240m, film

--transfer <string> Specify transfer characteristics ["undef"]
- undef, bt709, bt470m, bt470bg, linear, log100, log316,smpte170m, smpte240m

--colormatrix <string> Specify color matrix setting ["undef"]
- undef, bt709, fcc, bt470bg, smpte170m, smpte240m, GBR, YCgCo

[ToS_Maverick]

thank you very much for pointing this out!

x264 has these options:

Video Usability Info (Annex E):
The VUI settings are not used by the encoder but are merely suggestions to
the playback equipment. See doc/vui.txt for details. Use at your own risk.

--overscan <string> Specify crop overscan setting ["undef"]
- undef, show, crop
--videoformat <string> Specify video format ["undef"]
- component, pal, ntsc, secam, mac, undef
--fullrange <string> Specify full range samples setting ["off"]
- off, on
--colorprim <string> Specify color primaries ["undef"]
- undef, bt709, bt470m, bt470bg
smpte170m, smpte240m, film
--transfer <string> Specify transfer characteristics ["undef"]
- undef, bt709, bt470m, bt470bg, linear,
log100, log316, smpte170m, smpte240m
--colormatrix <string> Specify color matrix setting ["undef"]
- undef, bt709, fcc, bt470bg
smpte170m, smpte240m, GBR, YCgCo
--chromaloc <integer> Specify chroma sample location (0 to 5) [0]

now what besides --colormatrix do i have to specify to mark my stream as 709?
what's the meaning of the other options (--transfer and --colorprim)?

[pandy]

now what besides --colormatrix do i have to specify to mark my stream as 709?
what's the meaning of the other options (--transfer and --colorprim)?

IMHO --colormatrix bt709 --transfer bt709 --colorprim bt709 should be ok

x264 do not interpret such fields as colormatrix or color primairies, x264 only fill accordingly to the user command values which normally are undefinied, decoder must interpret and properly decode such video.

(--transfer and --colorprim) - IMHO meaning of these field are similar to mpeg-2 - important for analog source ie they describe characteristic of the analog source.

http://neuron2.net/library/avc/T-REC-H%5B1%5D.264-200606-I!Amd1!PDF-E.pdf
this should be helpfull

[hkazemi]

I've compiled a summary to hopefully consolidate the threads and address the confusion over colorspace and the usage of Colormatrix. It is available at http://forum.doom9.org/showthread.php?t=133982#post1090068

[CruNcher]

I think the most efficient Decoder @ the moment in this regards (displaying the output like the source looked) is CoreAVC it has a remarkable color and brightness trueness that i saw from no other Decoder so far :)

[bob0r]

.... By Simply following the specs..... yup truely amazing a Decoder following the specs these days! :eek: