[mythtv-commits] Ticket #9854: ISO playback problems

[MythTV]

#9854: ISO playback problems
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 Reporter:  Jim Stichnoth <stichnot@…>          |          Owner:  markk
     Type:  Bug Report - General                |         Status:  accepted
 Priority:  minor                               |      Milestone:  0.25
Component:  MythTV - Video Playback             |        Version:  Trunk
 Severity:  medium                              |  Head
 Keywords:                                      |     Resolution:
                                                |  Ticket locked:  0
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Comment (by markk):

 Replying to [ticket:9854 Jim Stichnoth <stichnot@…>]:

 Can I just point out that adding 3 different issues to 1 ticket is not
 helpful.


 > I recently observe 3 problems when playing ISO DVD rips.
 >
 > 1. Widescreen videos (16x9) switch to 4x3 aspect ratio at some point,
 which seems to be repeatable.  I suspect it happens when a subtitle shows
 up in the stream.  See attached mythfrontend1.log output for clues.  This
 happens with Slim and VDPAU Normal profiles.  One can "fix" this by
 selecting H.Stretch from the Adjust Fill menu.

 Does this happen spontaneously while watching a sequence? or does it
 happen after jumping to a chapter or manually skipping?

 > 2. ISOs with several titles take a long time to start up, and also to
 jump to the main menu.  See attached mythfrontend2.log output, where the
 time between 06:55:32 and 06:56:08 (36 seconds) is spent on the "Please
 Wait...." screen.

 This is a known issue that I've spent far too long trying to resolve. When
 playing back over a storage group, the libmythdvdnav object gets a
 RemoteFile object from mythtv to load the iso over the network. This uses
 a readahead thread to buffer playback but it is painfully inefficient at
 dealing with the various seeks and file checks that libmythdvdnav needs to
 do when examining the file structure etc. Blu-ray playback has a similar
 problem.

 The quick and dirty fix is to not use the readahead thread. This will
 generally reduce startup times to less than a second but you will almost
 certainly get playback issues due to the lack of buffering - especially at
 cell boundaries.

 If anyone has any other suggestions, I'm all ears.


 > 3. Jumping within an ISO video sometimes has accuracy problems.  For
 example, pressing "50i" to jump to the 50-minute mark may jump to the
 46-minute point (but a subsequent "50i" usually jumps to the right point).
 This is unpredictable and often happens only during the first jump (if it
 happens at all).  This is especially unfortunate when it happens as a
 result of the initial bookmark seek when playback starts.  Through
 experimentation, this seems to be a problem seeking to the desired frame,
 and not a problem converting between frame number and elapsed time.

 I can't reproduce this - can you try and narrow down the circumstances
 which trigger it?

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Ticket URL: <http://code.mythtv.org/trac/ticket/9854#comment:5>
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