[mythtv-users] mythtranscode FIFO on master - corrupted mp4 output

[Mark Perkins]

> On 21 Oct 2015, at 11:25 am, Mark Perkins <perkins1724 at hotmail.com> wrote:
> 
> 
>  
> From: perkins1724 at hotmail.com
> To: mythtv-users at mythtv.org
> Date: Wed, 21 Oct 2015 09:56:39 +1000
> Subject: [mythtv-users] mythtranscode FIFO on master - corrupted mp4 output
> 
> Is anyone using mythtranscode in FIFO mode on master? I am building a new backend on CentOS 7 and while the core systems seem to work well I am having trouble with my transcode script which worked on 0.27 / ubuntu 14.04.
> 
> For testing I am essentially using the script from https://www.mythtv.org/wiki/Example_Script_using_mythtranscode_in_fifodir_mode.
> 
> Essentially the output video is massively corrupted and is a series of horizontal lines across the whole screen. Audio appears to have worked fine. 10sec example with corrupted output loaded here: https://www.dropbox.com/s/8b1gpuwtza4ndmh/test.mp4
> 
> 
> As far as I can see there are no errors generated anywhere in the logging.
> 
> <..snip..>
>  
> Quick update. I tried with a recording from the new system, no change in behaviour. Same corruption is present.
>  
> I also managed to turn up these:
> http://lists.mythtv.org/pipermail/mythtv-dev/2015-July/074901.html
> https://code.mythtv.org/trac/ticket/12479
>  
> Which look very much exactly like the symptoms I am currently seeing. I will endeavour to revert the change and see if that improves things.
> _______________________________________________

Ok, reverting the commit identified in the ticket here: https://code.mythtv.org/trac/ticket/12479 has resolved this for me as well with one caveat.

During earlier troubleshooting I had increased the (ffmpeg) value of thread_queue_size to over 8000 to get rid of ffmpeg message "thread message queue blocking; consider raising the thread_queue_size option". I think it defaults to around 4. With the commit reverted ffmpeg would stall after processing 20-120 odd frames. Dropping the value back down to 16 seems to prevent ffmpeg stalling although I now get the message queue blocking warning again.

I have no idea what impact reverting the commit is likely to have, anyone have any suggestions? I think I will leave it reverted for now.
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