Mailing List Archive: MythTV: Commits

Ticket #7605: Jumpy DVD playback - lock contention

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mythtv at cvs

Nov 18, 2009, 12:45 PM

Post #1 of 5 (646 views)
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Ticket #7605: Jumpy DVD playback - lock contention

#7605: Jumpy DVD playback - lock contention
------------------------------------------+---------------------------------
Reporter: john.p.harvey@… | Owner: janne
Type: defect | Status: new
Priority: minor | Milestone: unknown
Component: MythTV - Video Playback | Version: head
Severity: medium | Mlocked: 0
------------------------------------------+---------------------------------
I have a problem playing back dvd's on a low powered system. Dual Core
Atom using vdpau graphics.
If the DVD's are imported and played from disk (local or network) it is
fine.
The playback is very jumpy and after digging around the problem is caused
by locking in dvdnav between avformatdecoder & dvdringbuffer.

Both call IsInMenu which calls into dvdnav_is_domain which does a lock.
For some reason avformatdecoder fails to get the lock for up to about a
second which causes the jumpy behaviour.

Just before calling that it avformatdecoder cals DVD()->CellChanged() &
DVD->InStillFrame() which are stored in DVDRingBuffer & don't do any
locking.

As a test i modified IsInMenu to cache the state and only call dvdnav to
update the cached value from methods in DVDRingBuffer that fetch new data.

Since avformatdecoder doesn't try to get a lock this seems to fix the
problem but could someone confirm whether or not this change seems
reasonable? If so i will submit a patch.

This doesn't really explain why avformatdecoder was being starved of the
lock in dvdnav but i nothing seems to change that,(enable/disable real
time threads, different sync methods, enable/disable hyperthreading).
I am running on ubuntu 9.10.

I have attached the patch i am using which definately helps with the
problem but may not be a good solution

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7605>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Nov 21, 2009, 12:50 PM

Post #2 of 5 (584 views)
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Re: Ticket #7605: Jumpy DVD playback - lock contention [In reply to]

mythtv at cvs

Nov 24, 2009, 7:56 PM

Post #3 of 5 (552 views)
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Re: Ticket #7605: Jumpy DVD playback - lock contention [In reply to]

#7605: Jumpy DVD playback - lock contention
------------------------------------------+---------------------------------
Reporter: john.p.harvey@… | Owner: skamithi
Type: defect | Status: assigned
Priority: minor | Milestone: unknown
Component: MythTV - Video Playback | Version: head
Severity: medium | Mlocked: 0
------------------------------------------+---------------------------------

Comment(by skamithi):

(In [22901]) Refs #7605. Jumpy DVD playback. patch provided by
john.p.harvey. will commit to 0.22.fixes in a week or two.

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7605#comment:2>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Nov 27, 2009, 10:39 AM

Post #4 of 5 (529 views)
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Re: Ticket #7605: Jumpy DVD playback - lock contention [In reply to]

#7605: Jumpy DVD playback - lock contention
------------------------------------------+---------------------------------
Reporter: john.p.harvey@… | Owner: skamithi
Type: defect | Status: assigned
Priority: minor | Milestone: unknown
Component: MythTV - Video Playback | Version: head
Severity: medium | Mlocked: 0
------------------------------------------+---------------------------------

Comment(by anonymous):

john.p.harvey, you are the man! This bug has been driving me nuts for at
least a year. I've had to resort to using a stand-alone DVD player to
watch rented DVDs ever since I upgraded to 0.21. I just applied your
patch to the 0.22.0+fixes22594-0ubuntu1 package that comes with Ubuntu
Karmic and behold, we can finally play DVDs properly again! Thank you for
getting to the bottom of this issue and coming up with a fix. Live long
and prosper!

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7605#comment:3>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Nov 28, 2009, 7:55 PM

Post #5 of 5 (512 views)
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Re: Ticket #7605: Jumpy DVD playback - lock contention [In reply to]

#7605: Jumpy DVD playback - lock contention
------------------------------------------+---------------------------------
Reporter: john.p.harvey@… | Owner: skamithi
Type: defect | Status: closed
Priority: minor | Milestone: unknown
Component: MythTV - Video Playback | Version: head
Severity: medium | Resolution: fixed
Mlocked: 0 |
------------------------------------------+---------------------------------
Changes (by skamithi):

* status: assigned => closed
* resolution: => fixed

Comment:

(In [22920]) Closes #7605. Internal DVD Player. Resolves Jumpy dvd
playback on low powered systems. applies [22901] to 0.22 fixes.

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7605#comment:4>
MythTV <http://www.mythtv.org/>
MythTV
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