Re: [Pfspd-users@sf.net] performance problems

[Bram R. <bra...@ph...>]

Rene, others,

After obtaining a test case from Rene, I did some investigations on the=20
current development
repository of cpfspd and pts.
Test conditions:
- linux executable, running on dimholt
- output to scratch disk on muscules file server
- command "pts translate corvette=5F8mbps.m2v corvette=5F8mbps.yuv"
- result is file of 3.6Gbyte; 1198 frames 1920x1080

Currently (development version of cpfspd), file is opened in mode "wb" for =

allocation,
then it is closed. With pts translate on mpeg, the file size is not known=20
in advance,
so it is initially created with size 22528 bytes.
After that, it is reopened in "rb+" mode. Then images are written into the =

file.
Result of "time":
real    18m11.415s
user    1m10.260s
sys     1m2.590s

As a special test, I forced opening the file in "wb" mode the 2nd time;=20
result:
real    2m23.710s
user    1m5.710s
sys     0m20.850s

Next test; force mode "wb+" is also very slow.

I tested opening in append modes (followed by a reset of the file=20
pointer), but that fails to give correct output.



So, just changing the fopen mode results in a performance penalty of a=20
factor 7.5...
Interesting observation...


Harold, any suggestion how to keep the file open, and still maintain a=20
simple interface
for both *nix and win32/cygwin?


Regards, Bram.

PS. Gerard, maybe this is related to your observations?
        What version did you use?
        You can subscribe this mailing list at
                https://lists.sourceforge.net/lists/listinfo/pfspd-users

--
A.K. (Bram) Riemens
Principal Scientist, DSP group, Philips Research
Office: WO-p-94, Postbox WO02
High Tech Campus 36 (WO), 5656 AE Eindhoven, The Netherlands
Tel: +31 40 27 43833, Fax: +31 40 27 44675
E-mail: bra...@ph...








Rene van der Vleuten=20
Sent by:
pfs...@li...
08-06-2006 13:04

To
pfs...@li...
cc

Subject
[Pfs...@sf...] performance problems
Classification








Dear Bram, Harold,=20

I am suffering from huge performance problems with "pts translate file.m2v =

file.yuv"; processing takes more than 10x longer than with the latest=20
released pts!! I suspect these are caused by your latest updates to cpfspd =

(since I did not see any obviously related changes in pts).=20

Could you please look into this?=20

Thanks!=20

Ren=E9=20

--------------------------------------------------------------------------
Dr. Rene J. van der Vleuten
Philips Research Laboratories
High Tech Campus 36
5656 AE  Eindhoven
The Netherlands

Phone: +31 40 2742941
Fax:   +31 40 2742630
mailto:Ren...@ph...=20
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