avisynth filter doubt

[tengo6dedos]

hw

ok, so avisynth filters like deblockers or denoisers help a lot when u want to clean a bad source but what happen when u want to clean artifacts that appear when doin a little compression? u can use any filter or there are special desing compression ones? could u throw in some compression filters names if there r any?

thanks

[unskinnyboy]

Blockbuster is one such. A different approach, but _may_ help reduce DCT blocking - DCTFilter. That said, if you are getting a lot of artifacts, you are probably compressing too much (I know, the obvious).

[Ranguvar]

Yeah. Just remember, you want to ease the amount of work the encoder has to do. If you're seeing a lot of blocks, try removing some fine (invisible noise), along with some fine detail, with UnDot(). Other denoisers can do well if you want to reduce blocking, but will remove more detail.

A better option would most likely be to use the filters in ffdshow, or even the AviSynth scripting option in ffdshow, to remove such artifacts on-the-fly when watching. The downsides are you're limited in how much processing you can do before the video stutters, and it obviously isn't going to work on hardware players.

[unskinnyboy]

Yeah. Just remember, you want to ease the amount of work the encoder has to do. If you're seeing a lot of blocks, try removing some fine (invisible noise), along with some fine detail, with UnDot(). Other denoisers can do well if you want to reduce blocking, but will remove more detail.You are suggesting the opposite of what he wants. He already knows about standard deblockers and denoisers. He wants to remove DCT blocking, which is different from the macroblocking of the source. If you remove more detail with a denoiser like UnDot, you are going to get more DCT blocking, not less. Blockbuster adds noise to the source, so the encoder will spend more bits there, thus reducing the blocking.

[Ranguvar]

Ah, sorry. I actually had not heard of DCT blocking before, and assumed it was macroblocking.

What does DCT blocking look like, please? And what causes it, usually? Google has no help. I've probably seen it before, just not had a name for it.

[unskinnyboy]

OK. Simply put, DCT blocking happens when areas of low detail are compressed too much by the encoder resulting in a kind of blocking, which wasn't in the source to start with. This would result in a high compression ratio, but when viewing the encode, you will see some annoying dancing blocks. Black areas or areas with low luma are particularly affected. This is an unwanted side-effect of the psychovisual enhancements some codecs apply. The way to combat this is to reduce the compression by lowering the quantizer or to raise the level of detail of the 8x8 block (which Blockbuster tries to do by adding noise). On the downside, this will lower the compressibility of the source and raise the bitrate needed to compress it.

[tengo6dedos]

thanks man, ill run tests with DCTfilter and blockbuster.


any other suggestions?

[foxyshadis]

Use a deband filter like the one built into ffdshow on playback. It completely eliminates most of this banding/blocking.

[tengo6dedos]

i searched for deband filters followin ur suggestion but it seems they cant be used on a script because they r for postprocessing? so i have to call them from ffdshow and set avisynth n postprocessing box and im good to go?

[tengo6dedos]

any other suggestions?

[unskinnyboy]

any other suggestions?
Well, did you try the previous suggestions (DCTFilter, Blockbuster etc.)? What was the outcome?

[tengo6dedos]

Well, did you try the previous suggestions (DCTFilter, Blockbuster etc.)? What was the outcome?

i got nice results, im just lookin for other options to try

[stax76]

If you use DGDecode you can use MPEG2Source("...", CPU=6)