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#1 Re: Fast JPEG decoder » Rendre jpegdec compatible multithread » 2017-01-18 12:39:48
I haven't done any recent testing on Jpeg Compression. I don't have a huge requirement for fast compression, so I wasn't thinking about doing testing for that, but it might make sense to do that as well.
At the moment, I don't see much point in using the TurboJPEG C API - as far as I can tell, the TurboJPEG C API for LibJpeg-Turbo is just a wrapper around the standard LibJpeg API, so it's unlikely to give any performance benefits - I expect that it's more likely to hinder performance slightly.
I haven't found a Delphi conversion for the TurboJPEG API and since I don't expect there to be any benefit from using it, I don't think it's worth the effort to do the conversion as the existing LibJpeg Pascal interface code that Zed linked to seems to work. Converting to TBitmap wasn't straight forward though with that API which is probably why I hadn't tried it previously - I'm thinking about modifying the existing library code to make it easy to convert to TBitmap since I've already done most of the work...
#2 Re: Fast JPEG decoder » Rendre jpegdec compatible multithread » 2017-01-17 14:39:04
OK, it turns out that in my previous testing, I was only using the standard LibJpeg and not LibJpeg-Turbo.
With some optimizations of my own code, I've now got the following results:
Iterations: 1000
Thread Count: 8
CPU: Intel(R) Core(TM) i7-4810MQ CPU @ 2.80GHz
Core Count: 4
Thread Count: 8
LibJpeg-Turbo:
Single Threaded Performance: 205 images per second
Multithreaded Performance: 801 images per second
Relative Performance: 391%
JpegDec:
Single Threaded Performance: 166 images per second
Multithreaded Performance: 593 images per second
Relative Performance: 357%
SynGdiPlus:
Single Threaded Performance: 149 images per second
Multithreaded Performance: 147 images per second
Relative Performance: 99%
NativeJPG:
Single Threaded Performance: 22 images per second
Multithreaded Performance: 91 images per second
Relative Performance: 414%
Standard Delphi:
Single Threaded Performance: 26 images per second
Multithreaded Performance: 165 images per second
Relative Performance: 635%
If I disable the conversion to TBitmap, I get the following results:
Iterations: 4000
Thread Count: 8
CPU: Intel(R) Core(TM) i7-4810MQ CPU @ 2.80GHz
Core Count: 4
Thread Count: 8
LibJpeg:
Single Threaded Performance: 232 images per second
Multithreaded Performance: 1082 images per second
Relative Performance: 466%
JpegDec:
Single Threaded Performance: 179 images per second
Multithreaded Performance: 728 images per second
Relative Performance: 407%
I'm planning to update the files on my web site some time tomorrow.
#3 Re: Fast JPEG decoder » Rendre jpegdec compatible multithread » 2017-01-15 07:39:11
@zed
Thanks for the suggestion.
I haven't fully tested it yet, but in my initial testing, single threaded performance with LibJpeg is only a bit over half that of JpegDec - and that's without converting the end result to a TBitmap which would slow it down even further (There doesn't appear to be any included code to convert to TBitmap so I'll need to add some code to convert from Scanlines)
Even when multithreaded, JpegDec is still about 50% faster, and again, the difference will only get bigger once I add code to convert to a TBitmap!
Of course, YMMV on different hardware...
#4 Re: Fast JPEG decoder » Rendre jpegdec compatible multithread » 2017-01-15 00:53:35
No problem - sharing is all in the spirit of open source!
I've copied your zip file over to my web site as a backup and added a link back to your server in case there are any future updates.
Thanks for all your work in adapting this library for Delphi in the first place!
#5 Re: Fast JPEG decoder » Rendre jpegdec compatible multithread » 2017-01-14 15:04:24
For the benefit of anyone wanting a thread safe version of JpegDec, I've made an updated version of the library available here:
The original code wasn't thread safe because it used a global variable to store a value - trying to use the code from multiple threads caused an exception. I've modified the assembler code to instead store the value on the stack.
Some performance statistics:
CPU: Intel(R) Core(TM) i7-4810MQ CPU @ 2.80GHz
Core Count: 4
Thread Count: 8
Iterations: 1000
Thread Count: 8
JpegDec:
Single Threaded Performance: 138 images per second
Multithreaded Performance: 439 images per second
Relative Performance: 318%
SynGdiPlus:
Single Threaded Performance: 117 images per second
Multithreaded Performance: 131 images per second
Relative Performance: 112%
Standard Delphi:
Single Threaded Performance: 26 images per second
Multithreaded Performance: 151 images per second
Relative Performance: 581%
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