the meaning of various tunings in x264

[codemaster]

The x264 encoder has the folowing options for "tuning":

- default
- film
- animation
- grain
- psnr
- ssim
- fastdecode

I'm assuming that these are optimisations based on the source input. For example, if I encode an animation, then it's best to use "--tune animation" when encoding, because this way, the encoder would be the most efficient at compression.

But I don't understand the other options listed above. For example, I don't understand what is "grain", and when shold I use it insteand of "film". And, based on what criteria I should determine if I should use "--tune film" or "--tune grain", and the other ones ?

[fritzi93]

Film is good for most anything if you're in doubt. As the name implies, it can do a good job preserving film grain. It will do a good job on animation too, although it's not optimized for it.

I'll let someone else elaborate on the other possibilities. Good luck.

[Selur]

film: ment for normal film material encoded at a decent datarate (lowers the inloop-deblocking and tweaks the psychovisual settings slightly)
animation: cartoon like material with large flat areas (boost deblocking, changes pychoviual settings doubles reference frames)
grain: for grainy (or really foggy) source material where the grain should be kept and is not filtered out before encoding (see: https://en.wikipedia.org/wiki/Film_grain); the movie 300 is a good example of a grains source
psnr: disables the psychovisual settings, which you normally do not want; this is mainly there for debugging and seeing how (https://en.wikipedia.org/wiki/PSNR) is affected by the settings choice
ssim: similar to psnr but here you aim for good SSIM (https://en.wikipedia.org/wiki/Structural_similarity) values; like psnr not really ment for normal use
fastdecode: this is ment for content that needs to be played back on systems with low cpu power; to archive the same quality that you would have without this tune option, you will have to boost the datarate probably more than 30% (fastdecode disables a lot of the essential bit rate saving, but cpu power consuming options of the H.264 standard)

Cu Selur

[maxrockpro]

So would you recommend using the film tune while trying to backup a Blu-Ray movie from BD50 to BD25 mkv file.

[Selur]

asssuming you use a decent bitrate or crf: yes

[maxrockpro]

Thanks for replying.

Here's my issue. I am trying to backup a Blu-Ray movie from BD50 to BD25 mkv file. With the following settings:
Video:
Framerate: Same as source
Codec: x264
Bitrate: 17000 Avg bitrate (2-pass with Turbo first pass)
Profile: High@4.1
No other changes from the source.
Yet, there is severe motion ghosting in action sequences.
I tried Film tune with constant and variable framerates to no avail.

[Selur]

Yet, there is severe motion ghosting in action sequences.

Ghosting is not something caused by the encoder (x264), it is something that is either in the source to begin with or is created to to wrong decoding (in example blend deinterlacing). If it's in the source and you want to remove it Avisynth with sRestore might help.
Sorry, but without a sample of the source all I can say is that this has nothing to do with your x264 settings but either with your source or the way you decode and/or filter the source.

[maxrockpro]

[QUOTE=Selur;2263914]

If it's in the source and you want to remove it Avisynth with sRestore might help.
Sorry, but without a sample of the source all I can say is that this has nothing to do with your x264 settings but either with your source or the way you decode and/or filter the source.

I understand. However, considering the source being the culprit, is there any tweaking in x264 that atleast reduce the ghosting?

If not and Avisynth being the only solution, could you give me tips or a link to instructions to use it?

[Selur]

I understand. However, considering the source being the culprit, is there any tweaking in x264 that atleast reduce the ghosting?

No

If not and Avisynth being the only solution, could you give me tips or a link to instructions to use it?

If you post a sample other people might be able to suggest how an Avisynth script to properly handle the source should look like.
If you don't know anything about Avisynth you might want to start reading and testing to get a hang of it starting with:
http://avisynth.nl/index.php/Main_Page#New_to_AviSynth_-_start_here
http://www.animemusicvideos.org/guides/avtech/amvappavisynth.html
http://www.afterdawn.com/guides/archive/using_avisynth.cfm
once you understand the basics about Avisynth using sRestore is rather simple.
What you normally do inside your Avisynth script, if you try to remove ghosting:
a. load your source with a input source filter
b. bob the source with a bobber (+ may be add some cleaning/postprocessing)
c. run the bobbed content through sRestore

-> Avisynth isn't something that will work by itself and just copying scripts rarely helps, so you really need to understand what you are doing. (googling for Avisynth and ghosting and reading how others tackle the problem isn't a bad idea either )

Cu Selur

[maxrockpro]

Scripts! Oh, Im in trouble!

[sanlyn]

sRestore is not an anti-ghost filter.

Without some kind of sample, no one knows what the problem really looks like.

[Selur]

sanly is right, sRestore is for deblending. (exorcist, LGhost and Ghostbuster are for ghosting removal)

[sanlyn]

Many people refer to blend and combing artifacts as "ghosting". But again, we need a sample or at least an image from the problem vid.