[mythtv] A couple of questions about mythtv 0.19

Michael T. Dean mtdean at thirdcontact.com
Mon Jul 10 21:01:17 UTC 2006

On 07/10/2006 04:37 PM, Hamish wrote:
> I have a couple of questions... I'm not sure whether these are features I just 
> don't understand, or genuine bugs... Hoping someone can help. The system is 
> combined front/back ends. AMD 64 X2 4200+. 3GB memory. Hauppage Nova card.
> 1. Why, when a file doesn't exist, does mythfrontend try 5 or 6 times to open 
> the file... Counting down the attempts each time? If it's not there the first 
> time, it isn't going to  be there the second... Or third. Or fourth etc.

Unless the file is a LiveTV file or preview pixmap or ... that's just 
been created but hasn't yet appeared in the frontend's view of the 
filesystem (i.e. due to file attribute caching for networked 
filesystems).  Or unless it's a LiveTV file that's being created, but 
hasn't yet been written to disk.  Or ...

> Isthere any way to tell it just admit the file isn't there?

Only by changing the code and running a non-standard version of Myth 
(that probably won't be able to play LiveTV and may have other problems).

> 2. It seems to be random chance but sometimes when a file isn't present on 
> disk, but is  onthe DB, you can't delet it. Yet other times you can. Why?

Long story.  Fixed in SVN trunk in [9490].  See ticket #1480 ( 
http://www.gossamer-threads.com/lists/mythtv/commits/188835#188835 ) and 
my very verbose description at 
http://www.gossamer-threads.com/lists/mythtv/dev/188846#188846 .

The fix hasn't been applied to 0.19-fixes because it technically adds a 
new feature (therefore, it's not a pure "fix").  Since it keeps coming 
up again and again, I'll see if I can convince Chris Pinkham (the one 
who committed the patch to trunk) to commit it to -fixes under a more 
liberal definition of a fix.

Basically, though, if you delete it first (i.e. enter Watch Recordings, 
scroll to the file directly, and then delete it without doing anything 
else), it should allow you to delete it.

> 3. Why is the interface so slow?  Ihave an AMD64 X2 4200+. Sitting in 
> the 'select a recoding to watch' screen mythfrontend is using 99% of one 
> core. Doing what I have no idea... (strace says it's looping on
> select(17, [16], NULL, NULL, {0, 5000}) = 1 (in [16], left {0, 5000})
> ioctl(16, FIONREAD, [0])                = 0
> gettimeofday({1152563349, 448771}, NULL) = 0
> select(17, [16], NULL, NULL, {0, 5000}) = 1 (in [16], left {0, 5000})
> ioctl(16, FIONREAD, [0])                = 0
> gettimeofday({1152563349, 448843}, NULL) = 0
> select(17, [16], NULL, NULL, {0, 5000}) = 1 (in [16], left {0, 5000})
> ioctl(16, FIONREAD, [0])                = 0
> gettimeofday({1152563349, 448911}, NULL) = 0
> select(17, [16], NULL, NULL, {0, 5000}) = 1 (in [16], left {0, 5000})
> ioctl(16, FIONREAD, [0])                = 0
> gettimeofday({1152563349, 448983}, NULL) = 0
> select(17, [16], NULL, NULL, {0, 5000}) = 1 (in [16], left {0, 5000})
> )
> This translates into extreeme slowness. Like 2-3 second between pressing a key 
> & taking action on it. 

Bad configuration.  (Can't really say more than that with the info 
you've given.)

> 4. Why do I get duplicate recordings? I thought it was designed to record one 
> showing of a program. Yet things like Dr Who, which is repeated, when set to 
> record any time any channel gets EVERY repeated episode. Same for channels 
> like ABC, Sky3 etc which may repeat the same thing 3 times in a single day. I 
> get all 3 runs of it.

You didn't set the duplicate-matching policy or there are actually 
differences in the episode titles (subtitles) and/or descriptions or ...

> 5. When deleting, sometimes the dialog that pops up says allow re-record, 
> sometimes not... What is this dependent on?

Because you haven't set a duplicate-matching policy on your recording 
rule?  (Hmmm.  This is becoming even more likely to be the answer to 4.)

> 6. What's the prebuffering pause for logged below? It seems to cause jerkiness 
> on playback (I've seem several people with it, but no answers. I did have it 
> a while ago & posted then, but it 'went away'. Not sure why. When I upgraded 
> to the X2 from an amd64 3200+ it came back... The software didn't change, 
> just the hardware..

(and configuration)

>   Since mplayer can play the same file no problems (With 
> about 25 CPU), I know it's not the machine. 
> 2006-07-10 21:33:49.122 Video timing method: DRM
> 2006-07-10 21:33:49.189 dropping back audio_buffer_unused
> 2006-07-10 21:33:49.253 dropping back audio_buffer_unused
> 2006-07-10 21:33:52.176 NVP: prebuffering pauseAAAAAAAAAAAAAAAAAAAAAAAAAAAAuLL
> 2006-07-10 21:33:52.209 WriteAudio: buffer underrun
> 2006-07-10 21:33:55.229 NVP: prebuffering pauseAAAAAAAAAAAAAAAAAAAAAAAAAuAALAL
> 2006-07-10 21:33:55.266 WriteAudio: buffer underrun

Probably due to the configuration problem that's causing 3.

> 7. Is there any way to resize the playback on the fly?

It always does.  It should scale to full-screen or full-window or 
whatever size is appropriate for your playback settings.

>  Failing that, can you 
> tell myth to use mplayer to payback?

Nope.  I think that's called Freevo.

>  I have no problems with mplayer, xine 
> etc, but myth playback seems to be a dark art to get working & fails on me at 
> the rop of a hat (Usually with the prebuffering pauses above).

Fix 3 and then see...


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