Using ffdshow for better DivX to (S)VCD (less blockiness)

[zizou108]

Hey all,

ffdshow is a DirectShow decoding filter for decompressing DIVX movies - can be found at http://cutka.szm.sk/xvid/xvid.html. The cool thing about using this (rather than standard DivX v3 or 4 or 5 codec DLLs) is that you have control over the amount of post-processing that occurs. When you are re-encoding DivX to (S)VCDs, you want to have the maximum post-processing to minimize blockiness. With ffdshow, you can force it to do max post-proc while decoding the DivX (no matter what your processor speed). This in unlike the DivX5 decoder, which reduces post-proc if it finds it cannot play vid back in real-time at full post-processing.

In TMPGEnc, make sure you turn off the OpenDML and VFW readers (under Environmental Settings/VFAPI Plug-In), leaving only the DirectShow reader on to read AVI files - then you are sure that ffdshow is being used to decode the DivX AVI.

I found great improvement in my SVCDs made from DivX AVIs by using ffdshow's "deblock" settings.

Hope this helps someone,

zizou

[Daagar]

Silly me, I just posted a question about decompressing divx files before conversion, and here this post is

A couple questions... I typically create a AviSynth file (from FitCD) that I load into TMPGEnc. As long as I clear all other DivX codecs from my system, will this still work? I was expecting ffdshow to be an .exe file, but it seems to be just a codec. How do I access its GUI (to get at things like the deblocking features you mentioned?)

Thanks for pointing this util out!

[Daagar]

Doh! There is no .exe, but the is a Configuration item added to Start->Programs->ffdshow. Answers that half

Any tips on the settings you use before going to svcd would be great to hear. Thanks.

[Daagar]

Doh! There is no .exe, but the is a Configuration item added to Start->Programs->ffdshow. Answers that half

Any tips on the settings you use before going to svcd would be great to hear. Thanks.

[zizou108]

Hey Daagar,

I had problems getting ffdshow to work via AviSynth - it made WMP crash and would not load up in TMPGEnc. ffdshow is a DirectShow codec, so you need to use the "DirectShowSource" command (rather than "AVISource") to be sure that AviSynth is using DirectShow to open the AVI file. It should work, but did not for me - maybe it will for you.

Here is a trick to be sure that ffdhow is in fact the codec being used: turn on "Show motion vectors" under the "Tray and Dialog settings" - you will see the little motion vector lines if ffdshow is in use (e.g., in the TMPGEnc preview).

My ffdshow settings are as follows:

• Codecs: I check them all, so that ffdshow is the decoder for all DivX-type files

• Postprocessing: Preset, at highest setting (turns on all deblock and dering); Automatic quality control unchecked (ensures that all post-processing is done, even if it causes video rendering to slow down); Processing Strength at max. I leave Level Fix off, but you may want to play with it and see what it can do.

• Noise: I usually do not add noise, but you may like the efect: it reduces visible blockiness in solid color areas (e.g., walls)

• Sharpen: again, I do not use this, but you may like to: try it

Note that ffdshow becomes the default codec used by Windows Media Player after you install it, so you can play your AVI in WMP, then choose Properties...Advanced-tab to get to the ffdshow settings. Try different settings out and immediately see their effect in WMP.

Have fun with it - it is a cool tool.

zizou

[Daagar]

Thanks for all the info. ffdshow is excellent! It turns out that ffdshow does so much, that there may be no need for AVISynth at all. I couldn't find an equivalent for TemporalSmoother, but that seemed to be the only thing lacking.

I played around with it for a bit last night, and was able to do all my resizing and processing via ffdshow, bypassing AVISynth completely. I'll try to hook it up as you mentioned just so I can see if temporal smoother makes a difference, but I can see the conflict. TMPGEnc usually requires that DirectShow be turned off for loading .avs files, while DirectShow needs to be on for ffdshow :P

For the record, the sharpen tool is pretty nice. It actually helps to reduce noise in the picture, so it helps reduce the final filesize of the resulting mpeg. Very handy if you're using something like kwag's templates. It is also a LOT faster than turning on noise reduction in TMPGEnc. I only tried 100% processing strength last night since I couldn't find documentation on how it affected things, but I'll crank it to max and see if I can tell a difference. Level fix I had to leave off... it did really screwy things to the brightness.

Thanks for the info about going to the Advanced tab in WMP... I was trying to change things in the Config panel and hope it took affect immediately, but of course that didn't work. Will make it much easier to optimize settings!

[zizou108]

Daagar,

Yeah, I like all the filters in ffdshow - some of these (like the resize and crop) were not in ffdshow just a month ago - keep checking for updates on the ffdshow website.

Using GraphEdit (http://www.digital-digest.com/dvd/downloads/graphedit.html), it is even possible to insert ffdshow as a filter when playing back MPEG1 or MPEG2 videos - so I was able to force a 480*480 SVCD to play back on my computer at the proper 4:3 ratio - pretty cool!

Thanks for your feedback re the noise reduction - I also am just starting to experiment with kwag's KCVD templates, and have been very impressed.

It seems to me that having DirectShow disabled in TMPGEnc should not (theoretically) affect the ability of Avisynth to read your AVI via DirectShow. I.e., I think you should be able to still use AviSynth with ffdshow to frameserve into TMPGEnc - but maybe not. As I said, I have not been able to get Avisynth to work at all with ffdshow on my system.

zizou