[GEM-dev] [ pd-gem-Bugs-2977716 ] pix_film with DS eats up cpu in W32

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Sun Aug 22 20:16:29 CEST 2010


Bugs item #2977716, was opened at 2010-03-27 17:26
Message generated for change (Comment added) made by zmoelnig
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Category: Pixes (pix_ objects)
Group: win32
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Matteo Sisti Sette (sistisette)
Assigned to: Nobody/Anonymous (nobody)
Summary: pix_film with DS eats up cpu in W32

Initial Comment:
When I send an [open( message to a pix_film object, if it uses DirectShow (as opposed to QuickTime) to decode the file, it starts consuming an enormous amount of cpu: around 30% of a 2.5GHz Intel Core Duo machine. Furthermore, it never stops eating that much cpu, even if you stop repdorucing the file (by setting auto to 0 and not changing the frame through the right inlet) and even if you disconnect it from the gemhead.

This happens with file encoded with various codecs: DV-PAL, H.264, Animation+, and I suspect everything else.

Note that if I open the files with QuickTime instead of DS (by appending the proper number to the open message), then this does not happen: the impact of opening the file on the CPU is minimal, almost impossible to note, and it only consumes cpu during few seconds after opening the file, and when _actually_ playing it (i.e. a gemhead connected to it and changing frame). That is, with quicktime pix_film only consumes CPU when it is supposed to, and it is much much less CPU: you can easily read 6 full-size DV-PAL files actually rendering some portion of them on the screen, and you can have a dozen of pix_film with [open(ed files without impact on CPU (or even many more, then the impact won't be on CPU but on performance in general due to the memory trashing).

This can't be normal: DirectShow is supposed to be much faster than QuickTime on Windows; also, any given media player will open a video file using DirectSHow and without eating up nearly as much cpu, especially when not playing.
There must be something wrong in GEM.



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>Comment By: IOhannes m zmlnig (zmoelnig)
Date: 2010-08-22 20:16

Message:
that's a touch one.
there might be a problem with Gem using frame accurate seeking for
playback, which might be handled better by QT than by DS.

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