[MPlayer-users] Are mencoder lossless codecs really lossless?
Carl Eugen Hoyos
cehoyos at ag.or.at
Tue Jul 9 15:04:56 CEST 2013
James Board <jpboard2 <at> yahoo.com> writes:
> Okay, so then if I start with some specific color space,
> compress with the lossless codecs, and then transcode back
> to that same original colorspace (assuming everything else
> is the same too: resolution, frame-rate, etc), then the
> frames should be exactly the same as the original (except
> for maybe small round-off errors, or artifacts of that
> nature)?
No.
When using a lossless codecs, no small round-off errors and
no artefacts are possible (assuming a bug-free encoder,
this is of course impossible, but recent tests with ffv1
were successful.)
The only possibility is that the original colourspace
is not supported by the encoder, but this is not the
case here, all three encoders support yuv422.
(x264 also supports it.)
Since you mention "frame-rate" above:
I don't think the frame-rate has any relevance here,
it is the applications responsibility to produce
correct timestamps at encoding and decoding, this
has nothing (or at least not much) to do with the
encoder (and does not affect the losslessness of
the codec).
Please do not top-post here, Carl Eugen
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