[Kdenlive-devel] kthumb crash? (was Re: [PATCH mlt] Clear audio and video context to NULL)

[jb]

On Friday 14 October 2011 13:31:24 Dan Dennedy wrote:
 
> I was thinking to do something like that in mlt_multitrack where I am
> currenty setting that value, but I had not yet decided on whether to
> add a constant or use double the track count or other.
> 
> > Mikko, I would be interested to know if these changes have an influence
> > on the crashes you experienced.
> 
> I was really curious about that huge stack of invalid clip dialogs.
> What do you think is going on there?

Using MLT in debug mode, I discovered several cases where FFmpeg did show a 
warning about insufficient thread locking around avcodec open / close.

After several of this warnings, the avformat producer became corrupted and 
unable to load any clip, or simply crashed, which might be the reason for 
those clips becoming invalid.

These problems were caused by concurrent uses of producers in Kdenlive, and 
also by a "weakness" in the sdl preview consumer that caused such corruption 
when doing the following steps very fast several times:

stop the consumer
delete the producer
connect a new producer to the consumer
start the consumer

Looks like when looping, sometimes the consumer was stopped while starting, 
which caused avformat locking issues. I now inserted an event wait to make 
sure the consumer is correctly started before attempting a stop which fixed 
the issue.

I managed to fix almost all cases that showed up on my 4 cores CPU, so 
Kdenlive should hopefully be more stable than ever now.

regards
jb