[theora] Theora 1.1 rate controller
gmaxwell at gmail.com
Mon Jul 13 22:19:58 PDT 2009
On Wed, Jul 8, 2009 at 12:40 PM, Thomas de Buman<tdbuman at gmail.com> wrote:
> Here are the bitrates I measured (VGA resolution):
> tx = target_bitrate (Mbps); ox = max rate observed at output of encoder
> (Mbps; approximation)
> tx: 0.7 --> ox: 0.7
> tx: 1.0 --> ox: 0.9
> tx: 1.6 --> ox: 1.1
> tx: 2.0 --> ox: 1.3
> tx: 4.0 --> ox: 2.4
> tx: 6.0 --> ox: 3.4
> tx: 8.0 --> ox: 5.6
On Tue, Jul 14, 2009 at 12:56 AM, <xiphmont at xiph.org> wrote:
> That's quite surprising. I use the bitrate management in Thusnelda
> (FTR, 1.1 hasn't been released yet, these are alphas) and have found
> it to be robust and correct. That's not to say bugs don't remain.
The current code will miss your target rate if you bump into the
finest quantizer (i.e. equal to -v10) or the most coarse (-v 0).
Does "VGA" here mean 320x200 (the highest res classic vga could do
with 256 colors)?
*Lossless* 4:2:0 320x200x30fps is only something like 23mbit, so if
the video is 320x200 I would expect pretty significant undershoot at
higher rates as shown here, though under high motion it would
undershoot less which might explain the concern that the results are
content related. That doesn't explain the discontinuity however.
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