In the DV25 codec, for every four luminance samples, each color-difference component is sampled just once (a 4:1:1 chroma subsampling scheme). In a 4:1:1 scheme, the C_b (blue-difference) signal is sampled at the same location as the first luma sample, and then that C_b colour value is repeated three times (while the luma signal is sampled at each of those points). The C_r (red colour-difference) signal is also sampled once and repeated three times.

This co-siting creates a Y/C delay that can appear as blockiness or lower resolution in scenes with high saturation, and particularly red saturation.¹

Can it be fixed?

No, sub-sampling artifacts cannot be remedied.

See also

Adam Wilt, The DV, DVCAM & DVCPRO Formats, 2000-2006.

References

^{1. Adam Wilt, DV Pix - Sampling Methods, 1998. ↩}