[mythtv] Re: TS Timing issues

Taylor Jacob rtjacob at earthlink.net
Sat Mar 19 16:54:01 UTC 2005


Quoting William Uther <willu.mailingLists at cse.unsw.edu.au>:
> 1) I've already posted information that significantly narrows down the
> bug (and put it in the bug report: id=221): e.g. TS only, Channel
> specific, 100% repeatable.  There is more - I suggest you go read the
> bug report if you want it.  All of it has been posted to this list in a
> clear format.

After some emails from Kent Williams I have determined the time issue is in the
frontend.. It doesn't seem to pickup on a seperate PCR PID properly in TS
mode..

As far as 2 more TS mode issues I just fixed these last night:

1. Startup Delay - I have removed the SDT scan at the begining of TS playback, 
it was trying to find a SDT table (DVB SI) and then falling back to a PAT, so
now it just looks for a PAT and plays the program described there.. Seems to
startup as fast as PS mode..

2. Mark Andersons av_remove_stream code was removing streams in
avformatdecoder.cpp so if you were changing channels and the same audio pid
existed on both channels it would get removed with this code, and never get
added back since the removal of PIDS was taking place in 2 places, but the
adding back was only in one..

3. I have one sample of a seperate PCR stream recording now that I will play
with, and see how that goes.. I should be able to fix it now that I am starting
to look into mpegts.c

> 2) I understand "the devs" are busy.  But I'm not asking someone else
> to fix it.  What I *would* like is just a little help understanding how
> the system works so that I can fix it.  This has the advantage that I
> can go on to fix other things.  So far I've asked for help a few times,
> and got nothing but silence.

Unfortunatly we don't get paid, so when something comes up in life or work
usually open source hobbies end up going to the side.. That was the case with
me for a while.. I appologize, but that won't chang anytime soon.. We don't
work for fun.. :)

> I'm sorry if I'm stating the obvious or something, but I feel it would
> be nice with a better structure for helping new people help around
> here.  Helping new people help => more devs => quicker fixes and a more
> vibrant community.  If people have to fight to join the mythtv-dev
> community, they wont.

Using bugzilla is the way to go in my opinion.. I have been fixing my personal
list of "broken stuff" first, and then i'll be movinging into the bugzilla DVB
related issues..

> And so I'll ask again.  Where is the best documentation on dvb and
> mpeg2 decoding?  How do I find out what a PCR PID is, and how I might
> see if it is separate from a video PID?  I've tried google searching.
> I've looked through the the linuxtv wiki.  I'm slowly finding stuff,
> but I have the distinct feeling that a few pointers from those who've
> been here before would really speed things up.  It would certainly help
> more than someone telling me what a bug tracking system is.

You need to get the docs from ISO.. 13818 I believe is the spec.. That explains
what a PCR it.. Its the Program Clock Reference.. Everything I can recieve in
North America its in the Video PID but it seems just down under you guys have
them seperate, so it makes fixing it even more difficult.. You can use dvbsnoop
to look at the PMT tables and see if the PCR PID is listed differently from the
Mpeg2 Video PID on the affected channels.. I am 99.9% sure thats the problem
since I have gotten a few different responses from others in Oz..

Taylor


More information about the mythtv-dev mailing list