Saturation difference between YV12 and I420 using x11 driver

[bdforbes]

I have a rawvideo I420 stream, and encoded it to an mpeg4 YV12 stream. They look the same using the xv driver in mplayer, but using the x11 driver, the I420 stream has a more saturated, unrealistic feel to it, and the YV12 stream looks fine.
Does anybody have any idea why this is? I thought I420 and YV12 were essentially the same.

[Stears555]

Have you any idea?

[Selur]

I thought I420 and YV12 were essentially the same.

they are, but that doesn't mean that decoder X handles them the same way

Using a higher verbosity when you call mplayer through the command line might show some differences,...