[vlc-devel] Re: Doing an lseek() with VOB files ...

John Michael Zorko j.zorko at att.net
Wed Aug 13 10:18:42 CEST 2003


Thanks for your input.

> Does the server VLC start streaming on a I-Frame when doing ff/rewind? 
> If not you get a jumbled-up video because you then have either a P or 
> a B-Frame and they depend on previous frames.

The server does an input_Seek() to the off_t of a sequence header / 
GOP.  Since I-frames are the first frame in the GOP, this shouldn't be 
an issue.  The real issue here is that, when VLC is playing from a 
file, seeking anywhere doesn't disrupt the video i.e. the seek bar in 
the GUI does not seek on I-frames, it seeks to an off_t that represents 
where the GUI bar was moved to, without regard to if this is an I-frame 
or not.  When playing from a stream, this same action (using the GUI 
seek bar on the server VLC) results in momentary disrupted video on the 
client VLC.

So, something is different when VLC is playing from a file and a seek 
happens, than playing from a stream and a seek happens on the server 
VLC.  Either the data sent from the server to the client is different 
in this case, or the code that the client VLC executes (the UDP access 
module, the MPEG demuxer, the libmpeg2 codec interface, and the 
video_output) is doing something different because it's a stream, and 
this something different is resulting in jumbled video for a fraction 
of a second every time the server VLC seeks, whether it's to an 
I-frame, GOP, sequence header, pack header or random off_t.  This is 
what i'm trying to find.



Falling You - exploring the beauty of voice and sound
New EP, "hope thrown down," available now at

This is the vlc-devel mailing-list, see http://www.videolan.org/vlc/
To unsubscribe, please read http://developers.videolan.org/lists.html
If you are in trouble, please contact <postmaster at videolan.org>

More information about the vlc-devel mailing list