[mythtv] DVB alpha-0.4

[Mike Wilcox]

Kenneth Aafloy wrote:
> Hi to you too!
> 
> Mike Wilcox wrote:
> 
> 
>>I seem to have hit a problem that, if I understand correctly, has the 
>>same symptoms of a wrong "use_ts" setting - I get zero-length 
> 
> 
> The use_ts should be fine as long as the card supports it.
> 
> 
>>    DVB#0 Poll timed out waiting for frontend device, retrying.
>>    <snip between 4 and 10 more of these...>
> 
> 
> I've removed this message now, as it's pretty useless
> (and was only for testing).
> 
> 
>>I decided to add some debugging into dvbrecorder.cpp to see what was 
>>happening with the PIDs and the use_ts parameter (I didn't trust that 
>>I'd set these correctly, and the debates on the mailing list left me a 
>>little, er, bemused.
> 
> 
> He, i'm a horrible coder, sorry!

It wasn't the code I was having problems with - more the understanding 
of how to put things into the table(s) - especially which PIDs go where, 
and use of comma-separated lists.

The solution, as ever, is to look in the code. the parsing in dvbchannel 
is the best hint :-)

>>++  //pthread_mutex_unlock(&dvbchannel->lock);
> 
> No wonder it wasn't working, it's not even initialized in dvbchannel.
> Strange though, that it has worked for me and others :)

That certainly explains something. But where is it declared? I can't see 
it in dvbchannel or in channelbase! Standard C and Java are my forte, so 
I guess I'm missing something :-)

>>    o some segv's after recording completes (not gdb enabled at the
>>    moment though).
> 
> 
> DVBCam & DVBSections is pretty ugly coded, and reported fucking with most
> things when they are actually not used (no cam in use) :)

I'll do as you suggested elsewhere, and eradicate it for now...

>>    o failure to display correctly if a channel changes something about
>>    the stream while recording is taking place. I don't know exactly
>>    what, but I've seen it twice related to the start or end of the ITV
>>    news programmes (and still have one recorded).
> 
> Hmmm, didn't quite get that!

Yes it is kinda complex :-(

I have a recording from a single channel that regularly causes problems 
when the recording is viewed - either in full or in the thumbnail.

The problem does not occur from the start of the recording (which is an 
ITV news broadcast, that displays as 4:3 taking up the entirety of the 
screen). Instead, it occurs approx 20 seconds in, at exactly the moment 
the news broadcast finishes.

When viewed as a thumbnail (while displaying the list of recordings), 
mythfrontend segv's at this point.

When viewed at full-size, the display changes from full-screen 4:3 to 
show a letterbox'ed 16:9 image. It usually starts with a green screen, 
then a few mpeg artifact blocks, but then proceeds to play - but with 
frames jumping back-and-forth 1-2 seconds. Imagine playing frames in the 
order:

1, 2, 3... 11, 12, 26, 27, 28... 36, 37, 13, 14, 15... 25, 38, 39...

I also get a stream of these in stdout/stderr of the frontend...

2003-09-07 17:03:31 Delaying to next trigger: 300519
2003-09-07 17:03:32 Delaying to next trigger: 220451
2003-09-07 17:03:32 Delaying to next trigger: 219497
2003-09-07 17:03:34 Delaying to next trigger: 244848
2003-09-07 17:03:35 Delaying to next trigger: 211192
2003-09-07 17:03:35 Delaying to next trigger: 224539
2003-09-07 17:03:36 Delaying to next trigger: 213078
2003-09-07 17:03:37 Delaying to next trigger: 226275
2003-09-07 17:03:38 Delaying to next trigger: 247757
2003-09-07 17:03:39 Delaying to next trigger: 212431
2003-09-07 17:03:39 Delaying to next trigger: 227040
2003-09-07 17:03:40 Delaying to next trigger: 207836
2003-09-07 17:03:41 Delaying to next trigger: 214333
2003-09-07 17:03:42 Delaying to next trigger: 266780

The sound plays fine while the video is doing this.

Now, if I let the recording get to 10 seconds, then hit the right arrow 
to skip over 30 seconds, both video & audio run OK.

I have seen this one other time (but no recording), which again relates 
to starting or ending a news broadcast. My guess is that there's some 
switch in the stream that the mpeg player can't cope with.

I can safely say I haven't the first clue how to go about debugging this 
- but I can recreate it easily. If anyone can give me some pointers, I'm 
willing to try though...

>>    o occasional lockup on changing live-tv channels. particularly from
>>    a qam_64 channel to qam_16 channel.
> 
> 
> This is also caused by cam & section stuff.

I'll see how it behaves with the snip...

>>    o occasional lockup when seeking forward or back in a recorded.
> 
> Discussed in earlier threads, i'm trying to track down what is happening,
> but no luck yet, feel free to give it a shoot..

That'll be fun. I might just try....

>>but I'm not so worried about these until I know the effect I'm having by 
>>losing the mutex.
> 
> 
> I'll try to take my eyes off the telly for a few minutes and fix it :)

Excellent. Are fixes going into another patch release, or direct into 
CVS now?

Cheers,

    Mike