Hello Achim,
I'm joining the discussion as I've been working on this issue with Boris.
Actually we've been facing 2 problems with Quartz Composer:
1. The first one was something like 'ghost' images appearing in a
composition frame where images from a QuickTime source movie were
rendered. The rest of the composition is made of still images
representing banners, logos, illustration images, etc.. . The QC
composition is quite complex and the total number of rendering patches
(Sprites or Billboards) reaches 15 and even more (more than 15 levels of
overlayed images).
We use the QC composition in a Cocoa application with a QCRenderer
initialized 'off-screen', and we write images (NSImage objects) from the
source movie (via a QTMovie object) on a published image input of the
composition. Then we call the snapshotImage: method of the QCRenderer to
get ouput images from the composition and put them in an ouput QTMovie.
As explained, we sometimes (not always) have 'ghost' images appearing in
the output movie, in the frame where the source video is rendered. This
ghost images randomly and sparsely occur (3 or 4 times per minutes of
generated video), and they correspond to other images used in the
composition (banners, logos,..), always appearing in their original
side, color, orientation, etc., so they may correspond to input image
buffers, substituing an output buffer... . Furthermore, these ghost
images usually appear in groups of 3 or 4, each separated from the
following one with a single 'expected' source movie image.
We had no memory leak issue with this setup, only 'ghost' images
2. The second problem was the one explained by Boris: to by-pass the
first problem of 'ghost' images, we tried to reduce the number of
rendering modules (sprites and/or billboards) in the composition and
using Core Image filters embeded in the composition to do the image
compositing (image overlay). We tried 2 things for that : 1) simply
using a CISourceOverCompositing filter in the 'edit filter function' of
the Core Image Quartz Composer patch. 2) coding the following Core Image
kernel in the CI QC patch :
kernel vec4 coreImageKernel(sampler bckImage, sampler topImage)
{
vec4 bckPix, topPix;
topPix = sample(topImage, samplerCoord(topImage));
bckPix = sample(bckImage, samplerCoord(bckImage));
return topPix + (1.0 - topPix.a) * bckPix;
}
Both of these solutions did the overlay work correctly but both lead to
a big memory leak, in particular with HD source movie images, rendered
in HD ouput images: in this case the 24 GBytes of our MacPro was eaten
in a few tens of seconds, while our Cocoa application doesn't use more
than 1,5GBytes of memory (according to the activity monitor of the Mac).
My hypothesis is that Quartz Composer actually does the image
compositing in GPU when using the rendering patches like sprites and
billboards, but that Core Image filters embeded in a QC composition does
not, thus working in RAM and causing the observed memory leak.
I have no idea now how to do our compositing work with these to issue,
wich really look like bugs in Quartz Composer...
Any suggestion would be appreciated.
Best,
Mathieu
*De : *Achim Breidenbach <ac...@boinx.com <mailto:ac...@boinx.com>>
*Objet : **Rép : Quartz Composer memory leak*
*Date : *27 mars 2012 09:28:04 HAEC
*À : *Boris Rousseau <boris.rouss...@powedia.com
<mailto:boris.rouss...@powedia.com>>
*Cc : *quartzcomposer-dev@lists.apple.com
<mailto:quartzcomposer-dev@lists.apple.com>
Hello Boris,
in my experience QuartzComposer does all the graphics processing in
the GPU not in the CPU. If your RAM goes up, this is usually caused
by the inputs you are using. E.g. a H264 video has a big memory
footprint. Can you describe in more detail, what your composition
does and what sources are you using? What does "suddenly" mean to you
(after certain seconds, randomly)?
best,
Achim Breidenbach
Boinx Software
On 27.03.2012, at 08:42, Boris Rousseau wrote:
Hello,
I am facing a memory leak while using Quartz Composer to process and
generate videos.
Quartz Composer starts processing the video in HD starting from
700Mb and suddenly raises over the RAM limit until the Mac Pro swaps.
Apparently, the issue is probably link to Core Image processing
while converting or rescaling images to HD but I am not sure about it.
Did anyone already have this problem, please ?
How do I debug Quartz Composer memory leak, please ?
Thanks for your help.
--
*Boris Rousseau*
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12A Avenue des Peupliers
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