[XviD-devel] inter48x48

[daniel smith]

> it think it's an motion estimation problem. internally, 2 identicall frames
> _should_ be the same. maybe some little adds could fix that ???

the frame xvid compares the current frame against (in terms of an ipppp sequence) is the *decoded* version of the previous frame.  because it's been compressed and then decompressed, it contains artifacts so that it is no longer a 100% identical replica.

> 100% agreed. I already thinked of that it's why i wanted "perfect" frames to
> be dropped

but what if the frame that you begin the sequence of repeated frames with, looks terrible because of a high quantizer?  such a frame may take 2 or 3 subsequent "correction" frames to start looking good.  thus dropping those frames would result in a rather ugly still image.

> I think of something : Creating a totally artificial frames that would be
> recognised by XviD as dropp-it
> something like a FF00FF00FF00FF00FF00FF00FF00FF00FF00............ patern in
> the Y plane for
> exemple : should be very easy to recognise BUT the filter should be in last
> and it's really a
> ugly hack :(

if you'd like, you could compile a version of xvid that looks for 0xDEADBEEF as the first 4 bytes of the Y block, and drops that frame.  that'd solve your problem - the harder part is finding a method suitable for commiting to cvs for everyone else.  open source means you can do as you please in your own sand box :-)

> we could always add a checkbox somewhere, but i think we can easily make a
> statistical
> 99,99...% perfect algo, using the fact that video is always noisy (even
> DVD's, even HDTV)
> specially on the chroma planes. and it could be disabled

such a dangerous feature should definitely be disabled by default.  pete's suggestion of optionally calling image_mad before compressing each frame may suit your purposes, if you can find the right threshold.  what algorithm are you using in your avisynth filter to detect duplicate frames, and how often does it miss frames due to small amounts of motion / noise?

dan
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