[Ffmpeg-devel] [PATCH] DV image quality improvement (original) (raw)

Rich Felker dalias
Sat Feb 25 23🔞42 CET 2006

On Sat, Feb 25, 2006 at 09:59:32PM +0100, Christian Iversen wrote:

On Saturday 25 February 2006 21:18, Dan Maas wrote: > The attached (very small) patch improves image quality from ffmpeg's > DV encoder, increasing PSNR by about 3dB on the BBC's test footage.

Not at all commenting on the quality of the patch in question (which is probably great), when are "we" (meaning "you" :-) going to stop using PSNR as a quality measure? There is only a quite weak correlation between percieved image quality and PSNR. There are other quality measures available that will give much better results. A difference of 3dB really proves very, very little about how good the result looks.

Umm, as much as PSNR sucks, 3dB is HUGE. In ffmpeg development, 0.1dB improvement is even considered fairly good, provided there are no visual problems. I agree that PSNR in general doesn't say much about video quality, but once you fix your testing to a particular codec (and thus a particular type of quantization/error) it's fairly well correlated with overall quality, at least for single frames. Often these 0.1-0.2dB improvements come with a perceptible visual improvement. Rate control makes the whole topic much more complicated of course, but that's mostly irrelevant with DV which is normally CBR.

Rich

More information about the ffmpeg-devel mailing list