On 19 Dec 2003, Florin Andrei wrote:
> You mean that for whole movies (> 1 hour) or for smaller scenes?
For the movie as a whole. Shorter scenes will, as you have seen,
run up against the limit and there's nothing "wrong" about that.
The guidline often is given as 20% but I've found 10% to be workable
too.
> The results? If i set -q so that the average is 10% lower than peaks for
> the whole movie thing, there will be scenes (not just a second or two,
> but entire scenes) where the bitrate will be pressed hard into the
Nothing wrong about that - as long as it's short term relative to
the entire movie.
> I am not exactly sure what's going on with those "bitrate crushed into
> the ceiling" scenes, but there's something weird about them. All bugs
Lots of motion would be one reasonable cause. Professional encoding
folks will apply a selective blur to those types of scenes - not to
the entire movie. The human eye would just be seeing a blur of
motion anyhow so a slight soften/blur by the encoder would lower the
bitrate to keep the peak rate in bounds.
Perhaps when Andrew gets the 2 pass encoding going there will be
hooks for selective filtering of regions where the encoder was running
up against the rate limit.
> everywhere in the video chain (recording, processing, storing, playing)
> tend to be much easier revealed by them.
> E.g., mplex reports the average being higher than the peak. :-)
Statistical anomaly - I've seen it too.
What I'd really like to have is a bitstream analyzer that could
take a stream and produce plots/reports about the bitrate (and other
info).
Cheers,
Steven Schultz
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