Re: [png-mng-implement] write a void array with libpng to harddisk

[Bob F. <bfr...@si...>]

On Sun, 23 Dec 2012, Goran wrote:

> 
> Thanks to you guys for the detailed informations.
> 
> Indeed, I have a high frame rate (80) which makes it impossible to write to a normal hard disk. But a SSD
> disk does the job. Even with several cams.
> 
> My problem is - as far as I see - the computation time. Is there a 
> GPU libpng (openCL) lib planed/possible?

Modern CPUs have quite a lot of power because they have between 2 and 
16 cores (not counting Xeon Phi).  The issue is usually that the 
software does not take advantage of the CPU and just maxes out one 
core.  Using a GPU adds new problems and the algorithm may not be at 
all suitable for a GPU.

Most CPU time is likely spent in zlib (compression).

I suggest multi-threading the writer so that multiple PNG files may be 
compressed at once.  The initial PNG should be encoded into RAM and 
then written contiguously using a block factor and sequence which is 
best for the underlying storage hardware.  Make sure that only one 
file is written at once from RAM in order to lessen contention.

Bob
-- 
Bob Friesenhahn
bfr...@si..., http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/