Deinterlacing filters use up more bits?

[rjc7394]

These filters (ie. Tomsmocomp) make XviD work harder (ie. searching) trying to implement deinterlacing algorithms?

If you add more and more internal or external filters does the output quality go down implementing all these algorithms?

[Teegedeck]

Sorry? XviD doesn't do any deinterlacing. If you feed XviD a deinterlaced source, that's fine; if you feed it an interlaced source you'll have to tell XviD that it's interlaced by using the 'interlaced' switch in XviD (meaning that the end result still will be interlaced).

Other than that: what you see is what you get; if external filters deteriorate the picture the encoded result will never look good. Nothing to do with XviD. But why would you use filters that deteriorate the picture? (What are 'internal' filters?)

Edit: For the bitrate-usage bit: Every filter potentially has influence on compressibility; generally properly deinterlaced sources take less bits than interlaced ones with XviD.

[henryho_hk]

XviD either compresses in a progressive manner or in a interlaced manner. Encoding interlaced materials in the progressive mode is simply a night nightmare.

Deinterlace filters generate a progressive output from the interlaced source. You can actually consider it an artifact, an intended artifact. There are many deinterlacing filters, some give the same frame rate, some give a doubled frame rate, some give a smooth picture, some give a sharp picture and some leave visible artifacts. All these affects the compressibility a lot.

However, unlike DivX, XviD does not have deinterlacing function built-in. [I'd rather use the other excellent AVS deinterlacers but not the DivX one.]

[rjc7394]

I was talking about deinterlacing in XviD using Virtualdub and Virtualdub's external (Fielddeinterlace, Kerneldeinterlace, Tomsmocomp) and internal filters (Smart, Area-based, blending, etc.) so it can be viewed on the PC without the interlacing. (All these deinterlacers output the original framerate.) They are counterproductive to compressibility?

[GodofaGap]

I was talking about deinterlacing in XviD
There is no such thing in XviD, it does not have a deinterlacer. It can either encode as progressive or as interlaced but it does not try to deinterlace either way. It is hard to say what interlacing does for compressibility, because obviously you are not encoding the same footage anymore after deinterlacing. It is true that normally progressive content is easier to compress than interlaced content (and that is not even condidering the efficiency of either mode in XviD).

[rjc7394]

Encoding in XviD while using an external deinterlacer in the Avisynth script. I know there's no deinterlacer in XviD just like I know there's no resizer, crop or color adjustment in XviD.
Does the external deinterlacer have an effect on the compressibility? I guess it depends on the extent of the interlacing.

[chilledoutuk]

As stated previously encoding interlaced content is normally allways less easy to compress in comparison to the same content that has been deinerlaced.

The varying filters for deinterlacing do affect the compressability depeding on how much detail there able to keep.

for example a simple field deinterlacing filter will just blend the fields together which looses a lot of temporal information and softens the image making it easier to compress.

A motion compensated filter such as toms predicts the temporal changes and uses that to fill in the gaps creating a more acurate progressive representation of the interlaced video.

The more information in this image makes it harder for codecs to compress however in my opinion this is more than made up by the fields not being blended and thus for all interlaced content i like to use tomsmocomp.

[GodofaGap]

I guess fieldblending could hurt compressability, but IMO fieldblending can hardly be called deinterlacing. It is more like trading one annoying frame property for another.