[vlc-devel] Re: 0.5.2 jerky

Derk-Jan Hartman d.hartman at student.utwente.nl
Thu Mar 13 22:48:09 CET 2003

On donderdag, maa 13, 2003, at 19:11 Europe/Amsterdam, Hans-Peter 
Fischer wrote:
> Christophe Massiot wrote:
>>> Audio quality seems to be better, but who cares when video is so 
>>> jerky that you can't really stand it. I've set audio frequency to 
>>> 16000 Hz. That made it quite smooth in the past, but doesn't any 
>>> longer now.
>> Your fix seems quite weird to me, but anyway if you want to restore 
>> the old behavior, you need to remove the plug-in named 
>> "libbandlimited_resampler_plugin.so".
> Thank you very much, Christophe. Deleting this plug-in really did the 
> trick. :-)
> One more question, though: Why do you think reducing audio frequency 
> is a weird fix? Of all the things I've tried to improve video 
> smoothness this one was the most effective. The difference in sound 
> quality is hardly audible here, and the gain in smoothness is 
> *tremendous*. Is there any disadvantage that I don't know of?

Well, maybe the audio doesn't need resampling on your system.
But for instance there were streams with 58Khz output going to 41Khz 
hardware. This produced an enormous amount of noise. Maybe you are 
playing 44khz audio to 41khz or even 41khz on 41khz, so it isn't as 
much of a problem for you, but especially for many mac users it was an 
enormous problem (most of the mac audio hardware can only handle 41khz 
and nothing else).

> The thing is, the audio and image quality of vlc are generally very 
> good now, but video playback is still jerky on my machine (probably 
> among other things because Linux programs and drivers can't take 
> advantage of the DVD motion compensation features of the Rage II+DVD 
> chip, right?).


> But smoothness of camera movements has a much higher influence on the 
> viewing experience than clarity of images and sound, I think. It would 
> therefore be really great if there was a mechanism that allowed the 
> user to sacrifice some image and/or sound quality to free some CPU 
> cycles for smoother playback. I don't know if this is practical, since 
> I don't know enough of how vlc - and DVD decoding in general - work. 
> Do you think something like that might be possible?

This is not possible in the current design of VLC i believe.
For DivX you can enable the hurry-up option of the ffmpeg component. 
That usually works quite well.

Derk-Jan Hartman
Videolan - VLC media player
Derk-Jan 'The DJ' Hartman
Co-Developer of the MacOS X port of vlc
Mail: mailto:thedj at users.sourceforge.net
WWW: http://home.student.utwente.nl/d.hartman/
Goto: http://www.videolan.org/vlc

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