Bug: H.264 Playback

[MuldeR]

Hi,
I've just noticed a strange effect on playing back H.264 encoded video in VLC. Problem is, that the video doesn't play smooth! It's not that much, so most times you won't even notice it. But if you take a closer look at the video, you'll notice the video is juddering. For example you can see this at scrolling texts (like News Tickers) very clearly! The problem is there and it is reproduceable. However the same video file plays 100% smooth in other players! So far I've tested MPlayer, Media Player Classic (with latest ffdhsow build) and Nero Showtime (Nero decoders). Only VLC produces juddering. So this MUST be a problem of VLC.

My Video is stored in AVI container and was encoded with latest x264 build (r399) in VirtualDub. Resuloutions is 640 x 480, Framerate is 25 fps. The audio is MP3 (CBR). Note: I use the latest nightly build of VLC for playback.

Hope you can fix that ASAP.

Greeeeeeetz
MuldeR

[MuldeR]

I did some testing: I extracted the audio and video stream from the AVI and re-muxed them with MP4Box. The resulting .mp4 plays 100% fine in VLC, juddering is gone. So now I think the problem must be somthing with the way VLC handles AVI files. Maybe the multiple B-Frames cause trouble? Since other Players don't have that problem, it shouldn't be too hard to fix the AVI splitter in VLC. Unfortunately I can't remux my AVIs to .mp4, since the remuxed file doesn't play in MPlayer for some reason (strange noise + heavy video artifacts)

Thanks for reply!

[MuldeR]

Has any of the developpers read that ???

[tonsofpcs]

What exactly do you mean by "juddering"?
Do you live in a country with 60Hz power or 50Hz power? (trust me, the answer may help me understand what you are saying)

[Vadar[]]

I've had some great help/explanations here: viewtopic.php?t=16006&highlight=

apparently H264 can be a problem an Raw aint Raw

[MuldeR]

What exactly do you mean by "juddering"?
Do you live in a country with 60Hz power or 50Hz power? (trust me, the answer may help me understand what you are saying)

Germany -> PAL -> 50 Hz

I mean the scrolling text is just not running smooth. Like one frame freezing for a few milliseconds and then jumping a few frames ahead. Don't know how to describe it any better. But on the scrolling text you see it very clearly! Nevertheless the whole video is effected. It's not that much, but you can see it and it's annoying...

Just to make clear: The video has been deinterlaced with a good filter before encoding. It's not a tv related probelm. In MPlayer or Media Player Classic (ffdshow) or even Nero ShowTime the vid plays 100% fine! Only VLC is effected !!!

[The DJ]

It sounds like a decoding order vs. display order issue of the frames. As far as i know, AVC video in .avi should be stored in Decoding order and shouldn't differ much from MPEG-4 in this case.

You can upload a sample to ftp://streams.videolan.org/incoming so we can take a look at it. (a couple of Megabytes should be enough). Please accompany it with a textfile with the name of the video, describing the issue.

[MuldeR]

It sounds like a decoding order vs. display order issue of the frames. As far as i know, AVC video in .avi should be stored in Decoding order and shouldn't differ much from MPEG-4 in this case.

You can upload a sample to ftp://streams.videolan.org/incoming so we can take a look at it. (a couple of Megabytes should be enough). Please accompany it with a textfile with the name of the video, describing the issue.

I'll do that right now!

[MuldeR]

So, it has been uploaded (H.264 Juddering Bug)

1. Please play in VLC and focus attention on the scrolling text (lower right corner)
2. Play with MPlayer or ffdhsow and you'll see juddering is gone


Thanks

[Vadar[]]

[see- [NM] ]

[MuldeR]

[see- [NM] ]

eh ???

[Vadar[]]

[NM] is just the traditional forum/disc. group/e-list convention for a post that has [No Message].

You put [NM] in the subject to indicate that the subject contains *all* there is ...
*This* forum won't let you post an 'empty message', however, and the Subject line got truncated - w/o warning - by the forum software ... so, my Subject/question was :

Is it OK if others take a look at that sample, gents ? [NM]

- I'm playing with H264 etc too.

[MuldeR]

[NM] is just the traditional forum/disc. group/e-list convention for a post that has [No Message].

You put [NM] in the subject to indicate that the subject contains *all* there is ...
*This* forum won't let you post an 'empty message', however, and the Subject line got truncated - w/o warning - by the forum software ... so, my Subject/question was :

Is it OK if others take a look at that sample, gents ? [NM]

- I'm playing with H264 etc too.

I can send you the sample video via ICQ

[MuldeR]

Will anybody investigate this ?!?!?

[tonsofpcs]

Well, upon examination of the file, it played in vlc, and when hitting certain frames (the same ones every time), it would pause, and apparently reinitialize the playback engine, restarting at the next keyframe. WinAmp and other players would pause for the single frames (holding certain frames for 2 framelengths [2/25 sec]) and then continue rendering, with a few errors, apparently assuming that the frames causing the problem were exactly the same as the frames before. I tried loading this file into an animation application, and upon attempt to load said frames, it crashed. My prognosis: the file is improper/corrupt on those frames, VLC does the right thing by waiting for the next keyframe, WinAmp and others do the wrong, but more you-freindly thing of attempting to play as if that corrupted were a duplicate, therefore: no bug.

[MuldeR]

@tonsofpcs:
Thank you for testing the file. But:

When you tried to play the file in Winamp, what DShow filtrer did you use for decoding ??? And which source-filter for splitting the AVI ??? IMO Winamp is not a very good tool for testing DShow playback. It doesn't give you much control over your filters and the performance is horrible. In order to test DShow playback you should use Media Player Classic or alike. Furthermore get the latest ffdshow (http://www.x264.nl) and maybe the Haali Media Splitter (supports AVI splitting) and it WILL play fine!

And did you try MPlayer ?!?!?! Also plays 100% fine!

Finally I don't know which "animation application" you used, but I loaded the file into VirtualDub and there were *no* broken or missing or doubled frames at all. Then I loaded the video into Ulead GIF Animator - just for testing - and again no problems. I was even able to make Flash animation from the video. There just were no broken frames.

Again: This is not a problem of the file, it's a software problem.
So please don't lay the blame on a "broken" file that fast!

[MuldeR]

Now, will anybody try to fix this problem ?!?!?!?!?!?!?!?

[MuldeR]

[The DJ]

I haven't found the issue yet. I'll have to bring in more hardcore AVC ppl to investigate the cause.

The only thing i can determine so far is that the AVI seems to use the 'packed' frame method for storing the B-frames, so DTS/PTS becomes different here then normal (The reason why avi shouldn't be used for MPEG4/AVC in the first place btw. use mp4 or matroska).

I'm not really familiar with how vlc/ffmpeg deals with this.

[MuldeR]

Okay. Thanks I hope you'll get it working...

I know there's a big discussion going on about using x264 with VfW/AVI
But AFAIK XviD use a similar method for storing B-Frames in AVI...

[MuldeR]

Just tried the latest nightly build. Problem is still there, unchanged

[MuldeR]

Again: Problem not fixed in latest nightly build.
Can we expect a build of VLC that plays H.264 correctly soon ???

[The DJ]

You can't expect anything. It's Open Source.

[MuldeR]

You can't expect anything. It's Open Source.

Sure. But will any of the devs try to fix this?
If not, I won't be able to use VLC for most of my Videos.