On Sat, Nov 13, 2010 at 8:36 AM, Eli Billauer <[email protected]> wrote:
> The truth is that I don't understand why people are so uptight about having
> their original footage going directly into Cinelerra. I mean, it's nice that
> Cinelerra supports several video formats, but somehow I'm only really calm
> when I feed it with MJPEGs. Meaning, take the original video, convert it to
> MJPEG using ffmpeg or mencoder and then use that file with Cinelerra.

The vast majority of digital video, uless you're a studio using
cameras that cost more than most cars, is 8 bit.  8 bit is not quite
enough dynamic resolution to avoid reasonably easy to see artifacts,
one reason that pro production people are so concerned with dither and
de-banding filters in production renders.

The problem with MJPEG is that it uses a different color space than
all other video formats, and the conversion isn't lossless.  Going
from any of the MPEG formats to MJPEG increases banding and
quantization noise, and it is noticable.  Every conversion from one
format to another, even the uncompressed formats, is doing lossy
colorspace conversion.  You lose a fraction of a bit (out of only
eight bits!) on every colorspace conversion.

That doesn't even get into the fact that converting from lossy format
to lossy format is also adding quantization noise and losing detail
because each conversion is... well... lossy.  There's no consumer
camera out there using a bitrate high enough to be completely
transparent as it is, and now conversion... plus conversion... plus
conversion... each genration is losing more and more.

Oh, and Cinelerra's colorspace conversion code is also subtly wrong at
practically every step, so you're losing more than you would be
otherwise because of that too...

Monty

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