Hi,
Christian Thaeter schrieb:
Johannes Sixt wrote:
On Mittwoch, 23. Juni 2010, E Chalaron wrote:
Hi all
I have an academic argument with someone here.
When I export in quicktime 422 yuv2 8 bits, is it compressed yes or no ?
To me it is not.
1. Define "compressed".
2. Define what you compress.
I think a nice definition would be "is is lossy?" ... but you are in the
twist to determine how much loss is there. For programmers its easy to
tell when there is some 'information-loss' in the mathematical sense,
the other variable which is not really easy to measure is if there is
any perceptional loss. Technology got quite ahead hiding the
'mathematical' losses from the human eye. But the big catch is that when
you process this data further it might reveal much visible artifacts.
And no, cinelerra has no lossless compression codec to my knowledge.
You have only the choice between uncompressed (really huge) or lossy.
But as Johannes saied, when your transformation to the output format
already drops information thats secondary. Most actions do and with 8bit
quantization there is really no much headroom to suppress perceptible
artifacts (color model conversion, color corrections, crossfades, ..).
IMO whether 8 bit YUV 422 is lossy or not depends on the source (== original)
format.
If the source is 8bit RGB, it's lossy (and compressed), if the source is
16 bit RGB it's even more lossy.
If the source is exactly 8 bit YUV 422, it's lossless.
If the source if 8 bit YUV 420, it's bloat :)
Burkhard
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