Memory usage seems to be proportional to file size when playing m4a files.

[Sebastian Dröge]

On Fr, 2014-01-17 at 17:58 -0500, Lei Miao wrote:
> After reading Apple's QuickTime File Format Specification and digging 
> into gstreamer's code, I figured out what caused my problem.
> 
> I should first point it out that when playing m4a files, the memory 
> usage of gstreamer is proportional to the time duration of the file, not 
> the file size.
> 
> QuickTime stores media data in samples. The number of a samples in m4a 
> files are huge. For example, a 6hr m4a file has about 950,000 samples. 
> Because qtdemux.c creates a sample table whose size is proportional to 
> the number of samples, the buffer could be very big. For an m4a file 
> 6:11:46 long, I got:
> 
> [...]
> 
> Could somebody take a look at this issue and improve qtdemux? Any 
> comments/suggestions are appreciated.

It could be improved by only loading a sparse version of that table
(e.g. every second entry only) or by lazy-loading the table (i.e. only
remember where it is and load whatever is needed when it is needed
during seeking). Or a combination of both approaches (note: the second
won't work very well in push mode).

-- 
Sebastian Dröge, Centricular Ltd - http://www.centricular.com
Expertise, Straight from the Source
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