FFDshow postprocessing...

[bugmenotwillyou]

This pisses off a lot of people and I really do not understand what the persons responsible for ffdshow (if any) are thinking.

By default (and that's by installing the latest version from x264.nl, which is advertised as what you need to play back h264), ffdshow will install with posprocessing, with exactly the only combination of options that DON'T WORK AT ALL.

(Changing "H264 deblocking" to "when decoding H.264 video" for example fixes it - the real fix if of course is to BAN POSPROCESSING WHEN DECODING H264 or at least reduce strength, since it sees quantizers like 25 and it applies a lot of strength because it thinks these are ASP quantizers - or that's what it seems)

Now in each playback guide you see "install ffdshow and disable posprocessing". Great, half people won't do that and will see washed out video and slower performance, the other half who do that will see blocky ASP video.

If that wasn't enough, to top it off, the default "Subtitles" options DO NOT WORK AT ALL. "Letterboxing" to 4:3 is selected, but "Use overlay mixer" in "Output" is not, leading to cropped subtitles on any widescreen video. (BTW letterboxing a 4:3 video to 16:10 for a widescreen monitor will crop it, which doesn't make sense and seems a bug)

I don't know what the policy for ffdshow is, but I'd expect for the default setting to make some sense, and for bugs that destroy video quality to be fixed. It's like the authors are purposefully attempting to worsen the quality "by default"... And it's so easy to fix...

I appreciate a lot the great work that is ffdshow, but I really don't understand why this is broken. Perhaps the default settings are never looked into since the people who could fix them always upgrade on top of an older version? Could somebody shed a bit of light on that for me? Thank you :)

[ChronoCross]

your an ass. those settings work by defualt on almost all codecs. if your having a problem with a particular settings make your own installer and use that. so dude you need to stfu. I personally have never had problems with the settings that you say. perhaps you should blame your own computer and that of your probably warez friends.

[bugmenotwillyou]

Perhaps I should have used less uppercase, sorry. Here's the problem I'm talking about:

Default settings:

http://img182.imageshack.us/img182/4148/default8eu.jpg (http://imageshack.us)

Disabling postprocessing:

http://img179.imageshack.us/img179/3800/nopp7hk.jpg (http://imageshack.us)

(The video is anamorphic, but that doesn't matter (Though with default settings, it will play with the wrong aspect ratio too))

The first image looks washed, the second one is correct. There are people already building custom installers with the settings fixed: an example is the CCCP project.

[ChronoCross]

the CCCP project is a way for anime warez groups to watch each others encodes.

As for that: it's not a bug. it does exactly as it's supposed to. try the same source using xvid I'm sure it looks way better using postprocessing than without. There are no codec specific profiles as far as I know and pretty much every codec benefits from postprocessing. if x264 is an exception that still does not constitute a complete installer redesign. However it might be good to put a post install readme or something to tell people about possible problems or a note on the website.

[bugmenotwillyou]

It's not a redesign or anything - it's just changing "when decoding H.264 video and decoder deblocking is off" to "when decoding H.264 video". This does not affect other codecs, and solves this problem with H.264.

Likewise, changing "use overlay mixer" from off to the "half-marked" state makes a lot of sense: it allows correct aspect ratio playback and subtitle cropping, and doesn't break anything (falls back if it can't be done).

I've hit these problems multiple times, and when I forget to adjust these settings they'll eventually show up. Just a heads up.

[foxyshadis]

It's been this way since I reported it 9 months ago, and I'm sure before then. It's definitely a legitimate bug that's easily fixed by changing one setting, because post-processing was already re-engineered for this one codec a year ago, but set to the wrong defalt value. (In fact, on second thought the bug is that there's any choice; h.264 with extra pp, or decoded without deblocking, is way out of spec, the only possible rationalization for it is if you always watch encodes made with deblocking off.) It was quite frustrating to find out why every encode looked terrible initially, and it's a pain to tell everyone "make sure you click here, here, here, and change this setting, and no I don't know why it's that way". What's the other choice, tell them to buy nero's decoder or coreavc?

There's another place postprocessing is misapplied to: lossless video. What? Why? At least other formats PP is applied to have a checkbox to disable it per-format. I've resigned myself to just turning it on or off as necessary depending on what I'm watching.

Kind of belongs in the ffdshow thread, or at least the video codecs forum.

I don't even touch colorspaces, AR adjustments, and ffdshow subtitles anymore, that's a complete snake's den in my experience.

[Audionut]

I just disable it altogether. If your making an encode with blocking, your not doing it right.:D

But I just checked the ffdshow build I'm using, and it's default enabled to only deblock h264 if decoder deblocking off.

[Livesms]

Can somebody tell me - what should i do with all this ffdshow postprocessing?

By default i get "when decoding H264 and deblocking off"

But changing to "when decoding H264" i get better picture but 10 fps :(

And it's look like some bug, cause switching off postprocessing at all gives me 30-32 % CPU load playing x264 video (640*480).

Shots
1 - off (http://dump.ru/files/5/5595896344/1%20-%20off.JPG)
3 - when decoding H264 (http://dump.ru/files/6/67430200/3%20-%20when%20decoding%20H264.JPG)
2 - when decoding H264 and deblocking off (http://dump.ru/files/5/5933361529/2%20-%20when%20decoding%20H264%20and%20deblocking%20off%20.JPG)

[SergeyFedosov]

Enable postprocessing, presets, slider to the right. Automatic quality control 100%. No more postprocessing.
About deblocking. Do not use forced deblocking for high bitrate encodes!!! It is only suitable when playing the low quality video!!! Noticeable and annoying blocks appear at low bitrates encodes, when the videosample cannot be sharp by default. The only sharp thing would be exactly those macroblocks. Therefore, deblocking removes eye catching artifacts and smooths quite a little the rest of the picture (which is not sharp from the beginning). On the contrary, application of deblocking to a good quality video would inevitably deteriorate the picture: there are no macroblocks to remove, and instead the smoothing procedure is applied to the rest of the picture.

[foxyshadis]

I think you missed the point of this thread, which concerns h.264 (encoder side) deblocking, and the way ffdshow is doubling up the deblocking in some modes because of either an implementation or design error.

[rezard]

Now in each playback guide you see "install ffdshow and disable posprocessing". Great, half people won't do that and will see washed out video and slower performance, the other half who do that will see blocky ASP video.

I'm confused. first of all, it is strange that the PP configuration contains h.264 deblocking.

I have been using ffdshow without postprocessing so far.
turning off PP also disable h.264 deblocking?:(

by the way, what's the meaning of 'skip deblocking when safe' in 'Codecs' configuration?

[foxyshadis]

Basically, don't deblock B frames for a speedup. (Actually any non-ref frame, but that's usually mostly B frames.)

But PP and h264 deblocking are unrelated, don't worry, only the option above affects decoding. It's only passing through the PP filter that you can enable extra deblocking, strangely.

[Dark Eiri]

Do what I did! Use CoreAVC :D

[Blue_MiSfit]

roger that. CoreAVC + Overlay Mixer +MPC makes one fast AVC decoder. I can watch full res NTSC stuff on my 700MHz P3 lappy over wireless without dropping frames!

I use ffdshow for YV12 processing , so that I can use lanczos4resize. This only works on my desktop of course, given the high CPU requirements.

I agree that the default setting should be changed, PP should not be activated by default for h.264. This shouldnt be too hard to impliment. Still, you get to choose when installing ffdshow if you want PP to be enabled by default. I personally hate PP, and only use it to watch crappy old rips that I made before I knew what I was doing and am too lazy to re-do :)

~MiSfit

[JarrettH]

Anything looks better without the postprocessing in ffdshow. I don't see the point of it.

[DarkZell666]

Anything looks better without the postprocessing in ffdshow.More precisely : anything encoded correctly doesn't need PP to be watchable. Actually, I've got a Mary higgins clark DVD which is terribly noisy for which only PP would reduce the noise in a pleasant way.

[mike_lee]

Anything looks better without the postprocessing in ffdshow. I don't see the point of it.

I'm glad you said that. As I was reading this thread I was thinking to myself "Damn, I guess I'm gonna' have to turn post processing back on."

[LoRd_MuldeR]

Sorry, still confused.

What exactly does the "H.264 deblocking" option on the "Postprocessing" page mean? Does it refer to H.264's own deblocking or to ffdshow's additional postprocessing? What do I have to select if I want to keep H.264's deblocking on but I do *not* want any additional deblocking ??? I always thought to completely disable the "Postprocssing" filter is enough and the "H.264 deblocking" option doesn't do anything then. Is that correct and does it keep H.264 inloop-deblocking enabled?

IMO this should be changed in ffdshow to make it more clear...

[foxyshadis]

How it's suposed to work is that you put it on "when decoding h.264 and decoder deblocking is off" so that if it was encoded without inloop and looks crappy you can get some pp.

But because of a longstanding code bug, the meanings are all reversed; "off": it's always on, "always": disables pp entirely, including for asp, "h264 video": it's always off, "h.264 video without deblocking": it's off when inloop is disabled and on otherwise. Makes sense, eh? The wrong setting obviously doubles up inloop.

The entire idea behind it is flawed though; turning inloop off is rarely done except for HD, where it's relatively unimportant. Most of the time when inloop is off it's because video is too low quant (ie, high quality).

[LoRd_MuldeR]

How it's suposed to work is that you put it on "when decoding h.264 and decoder deblocking is off" so that if it was encoded without inloop and looks crappy you can get some pp.

But because of a longstanding code bug, the meanings are all reversed; "off": it's always on, "always": disables pp entirely, including for asp, "h264 video": it's always off, "h.264 video without deblocking": it's off when inloop is disabled and on otherwise. Makes sense, eh? The wrong setting obviously doubles up inloop.

The entire idea behind it is flawed though; turning inloop off is rarely done except for HD, where it's relatively unimportant. Most of the time when inloop is off it's because video is too low quant (ie, high quality).

Okay. But if I disable ffdshow's "Postprocessing" filter (this is what I'm used to do), will the "H.264 deblocking" option still have any effect, or can I ignore it? And will I still get inloop-deblocking (this is what I want), as long as I don't disable it on the "Codecs" page ???

[foxyshadis]

Yes, disabling PP has no effect on normal decoding. (Easy enough to test!)