A noob question

[Tanshu]

I searched the forum, but could not find an answer to this question i had in mind.

If the video has a few successive frames which are exactly identical, does the codec improve the picture quality with each frame or is it the same as the first frame. So, for instance, the first frame is encoded with a lot of artifacts, will all the subsequent frames show them or will try and improve it?

[Blue_MiSfit]

in my experience, very similar frames do get progressively better. However, this is surely encode dependent. Some crappy release group rip might be horrible, and one well done encode might really exhibit artifact cleanup.

It all depends on the settings. As all things do.

[Tanshu]

Thanx Blue, but I was wondering as the codec only tries to see the difference between the frames, once the initial frame is encoded badly, won't the other frames remain bad (as there is absolutely no difference in them). or does the codec compare the image it has calculated and the next frame?

[bond]

Originally posted by Tanshu
If the video has a few successive frames which are exactly identicala smart codec will write n-vops (not coded frames) in such a case, which means that the decoder will display the same frame again
currently xvid, 3ivx and nerodigital can do this

and when using a smart container (which excludes avi) you could have a variable framerate stream

[Tanshu]

Thanx Bond. That accurately answers my questions. This means that all the frames will have the exact same quality. So, if the first frame was encoded such that it exhibits artifacts, all the successive frames will.

[Koepi]

That's not all the truth:

the encoder compares the encoded frame with the reference (source) frame. It will, if possible, replace "bad blocks" with better ones - for example if the artefacts in the encoded reference frame are so bad that they're measured and above a certain threshold - otherwise a nvop would be written, as bond mentioned.

I hope this helps,

Regards
Koepi

[Tanshu]

Thanx Koepi that clears the whole matter up.

And also thanx for Xvid all the releases to date including 1.0.0 :)