[Ffmpeg-devel] Video compression and quality of codecs.

Robert Swain robert.swain
Wed Apr 5 14:22:09 CEST 2006

On Wednesday 05 April 2006 11:44, Bogdan Mustiata wrote:
> I have tested the H263 codec in order to achieve best compression and
> quality (an utopia, I know).
> After playing around with bitrates, resolutions and framerates I

Usually the aim is for the "best" quality when these are fixed, though 
sometimes it is reasonable to have the bit rate fixed and alter the other 
two, such as for a stream encoded in real time.

> obtained something like:
> Bitrate:	2750
> Rezolution:	352x288
> Framerate:	10 fps
> Keyframe:	1/s (one keyframe at a second)
> KB/s		29-31.
> (KiloBytes per second)

Bit rate 2750, KB/s 29-31.... uhhh? Do you understand what bit rate is?

> The problem was that I was getting some small (and sometimes bigger)
> squares (done probably by the super-sampling).

These could be blocking artifacts due to quantisation if the bit rate is 
indeed ~30 kilobytes per second, I would doubt such usual artifacts would be 
visible in a 2750 kilobits per second (~350 kilobytes per second... 8 bits 
per byte on most modern systems).


> What astonishes me is the quality which was so much better on the WMV

Probably a case of misuse of the h.263 codec if the quality difference is 
_huge_ versus the current WMV9. Not to say that WMV9 shouldn't "beat" h.263, 
but I wouldn't have thought the difference would be huge. (h.263 has in-loop 
filtering doesn't it? Or is that h.263+? Or am I insane? :))

> Anyway, regarding strictly compression, the question that wonders me is:
> which is the best codec that still keeps a good quality in FFmpeg not
> regarding CPU consumption, memory or other factors, simply compression?

Codec recommendations are pretty much as Luca says, though I'd place emphasis 
on x264 at the moment.


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