[FFmpeg-user] YUV->RGB conversion. What is the default matrix used?

Tim Nicholson nichot20 at yahoo.com
Fri Jul 6 16:54:41 CEST 2012

On 06/07/12 14:49, Mike Scheutzow wrote:
> Tim Nicholson wrote:
>> Yes, but the coefficients are the same as 624-4. So is that really the
>> case, or are they just there for "future expansion" and yet to be
>> properly populated?
> It looks to me like 'ITU-R 624-4 System B,G' is better known as 'ITU-R
> BT.470 System B,G'.

No wonder I was confused.

> And according to this link, 'Smpte 170M' and 'ITU-R BT.470 System B,G'
> are extremely similar colorspaces:
> http://en.wikipedia.org/wiki/RGB_color_space
> so, it's not surprising that the coefficents match.

and overall it suggests that ffmpegs default of

#define SWS_CS_DEFAULT 5

is the PAL/SECAM setting (BT470 B G)  which has the same values as the
NTSC (170M) which is also the same as the 601 values.....

> Mike Scheutzow
> _______________________________________________

> [...]

Thanks for you assistance in this, now back to my colourbar generator
with the right values....


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