Gapless Playback Pipeline Problem

[Sebastian Dröge]

On So, 2015-01-18 at 23:36 -0500, David Griffin wrote:
> I'm trying to recreate what this person does with his concatenation element
> that will be in 1.6:
> https://coaxion.net/blog/2014/08/concatenate-multiple-streams-gaplessly-with-gstreamer/

(Author of that here)

> In a pad probe on the EOS event of a sink pad, I block the source pad of
> the pad before that sink pad and then I block the sink pad. Then, I unlink
> the same two pads. The element before the sink pad is a bin of many
> elements. I then remove the bin from the pipeline and put it in a linked
> list for disposal outside the probe. Then, I insert a bin that is a
> prerolled bin of elements like the one that was removed from the pipeline.
> The new bin was created using the same function I used to create the part I
> removed. The song before it plays successfully. I lastly set the prerolled
> bin to a playing state from paused. All of seems to work successfully to
> the point I described. The problem is when I try to link the pads of those
> two elements, the main thread locks up. I’m not sure why and debug info
> isn’t giving me and useful information. Here’s a graph of my pipeline
> directly before trying to link those two pads:
> http://i.imgur.com/6PYDlAU.png
> 
> I also tried doing all of that in a function run using g_idle_add so it is
> asynchronous, but I get the same deadlock result when linking the two pads.
> Here is my code:
> https://drive.google.com/file/d/0B9XMbfqJukNfUEVSQzBNQzd3N2c/view?usp=sharing
> 
> The relevant code is at 556 and the deadlocking pad link occurs at 707.

Could you try to get a minimal testcase for that deadlock, or a
backtrace of all threads when it happens? That might help and doesn't
require anyone to read through a few hundred lines of code :)

-- 
Sebastian Dröge, Centricular Ltd · http://www.centricular.com
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