On Thu, 27 Mar 2008 15:06:00 +0100, Marcin Kostur
<[EMAIL PROTECTED]> wrote:
2008/3/27, Herman Robak <[EMAIL PROTECTED]>:
On a modern dual core it shouldn't be, but in Cinelerra 2.x it is.
Richard Spindler has run some benchmarks on this, and if I recall
correctly, he could decode two HDV streams on a laptop and still have
CPU power to spare.
Decode 2 streams is not enought. One needs backward play, play from
random place. 2 streams mean - 1 track + fade transition ;-)
Yes. Backward play should be full speed, and it ought to start
instantly, not with a half second delay. If Cinelerra prerendered
video from the cursor back to the next I-frame, it could achieve that.
During forward playback Cinelerra should retain at least a couple of
GOPs in a cache, so instant backward playback always would be possible.
This is technically doable (but not implemented in Cinelerra) for all
but a few corner cases. In those corner cases there should at most be
a lag of about 1/4 second. I expect this of Lumiera. :-)
Play from random place would require to decode an average 1/2 of GOP in
1/25s.
Only in rare cases the editor will only have 1/25s available to
produce a "difficult" frame in time. The _average_ time must be
1/25s or less, but a clever editor should strive to get a little
ahead as soon as it can. Asynchronous decoding is the naive way.
More clever ways are needed, like selectively pre-rendering regions
that will likely fail to render in realtime.
On dual core PC with soft composer fade transition gives me 7-9fps ;-)
That's because Cinelerra isn't as clever as an HD video editor needs
to be.
--
Herman Robak
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