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

John Michael Zorko j.zorko at att.net
Wed Aug 13 23:57:35 CEST 2003


> I missed that one and did not look at the code in system.c (perhaps I 
> should)

No worries <smile>.

>> Anyway, that fopen / fprintf / fclose only happened on the client VLC 
>> 7 times during my test, while I seeked on the server VLC providing 
>> the stream dozens of times.  Can I infer from this that the server 
>> VLC, after a seek, is not setting the discontinuity bit in the TS 
>> header correctly before sending it out?
> No, because you are looking at the wrong place I think. Only at the 
> creation of TS packet the discontinuity bit can be set in the header. 
> How the access/demux can tell the packetiser/muxer? I do not know.

The fopen / fprintf / fclose I put in there wasn't trying to find where 
the bit it set, but rather to see if the bit was set by the server VLC 
whenever it did a seek (since the code that looks to see if it is is on 
the client VLC).  My tests indicate that it's not, so now i'm trying to 
find out where it would be / should be.  So far, my best guess is a 
function in vlc_root/modules/mux/mpeg/ts.c called PEStoTS() or 
something like that.  This function seems to fill out the TS header 
(found it by grepping for the sync byte code), so this is what i'm 
endeavoring to do right now:

1. figure out how to set the discontinuity bit here -- can you help 
with this?
2. set this bit whenever the server VLC does a seel
3. see if this bit gets over to the client in the TS header
4. see if this fixes the jumbled video problem

> Can you tell which scenario you were using when this 
> fopen/fprint/fclose
> gets triggered?

The test scenario is a VLC acting as a server, and another VLC acting 
as a client (same or different machine -- i'm currently using a Mac 
dual G4 running OSX 10.2.6 as the server, and a Mac iBook 900 as the 
client, but I also see the issue on RedHat Linux 9).  Using the rc 
interface or the GUI on the server VLC, I do the seek, and see what the 
client behavior is (if the video is jumbled for a bit after the seek).



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