How to compile libjpeg-turbo for Android?

DRC — Fri, 15 Sep 2017 17:55:33 -0000

BUILDING.md contains instructions on how to build libjpeg-turbo for Android. Also, I recommended that you take advantage of the libjpeg-turbo mailing lists (on Google Groups-- https://libjpeg-turbo.org/About/MailingLists) for community support, not these forums. These forums are a legacy feature, and generally only I read them.

How to compile libjpeg-turbo for Android?

Kiran T Patil — Fri, 15 Sep 2017 07:33:36 -0000

Dear @starsoul,

Please provide sample Android code of how to access libjapeg-turbo api ?

I would like to know, how did you compile and linked the library with Android.

Please help me, since I am newbie to Android.

Thanks.

tjDecompress2 takes more time to execute if called after a delay

DRC — Thu, 30 Mar 2017 16:26:31 -0000

If you can somehow profile the code and determine that the slow-down is due to a libjpeg-turbo function, then I'm happy to look at it, but otherwise, the evidence we have at the moment would suggest that this is a problem with Android and not libjpeg-turbo.

tjDecompress2 takes more time to execute if called after a delay

Ahmed Faraz — Thu, 30 Mar 2017 05:04:22 -0000

I even tried it on LG g4 http://www.gsmarena.com/lg_g4-6901.php and the results were same

tjDecompress2 takes more time to execute if called after a delay

Ahmed Faraz — Thu, 30 Mar 2017 04:24:21 -0000

Your test program is also causing the same problem on my system. It is Qualcomm Snapdragon 805 Inforce 6501 kit and I am using anroid OS

tjDecompress2 takes more time to execute if called after a delay

DRC — Wed, 29 Mar 2017 16:52:48 -0000

But note that you have never specified what operating system or hardware you are using, nor did you provide a standalone program for reproducing the problem. If my test program still causes the problem on your system, then please give me details about that system.

tjDecompress2 takes more time to execute if called after a delay

DRC — Wed, 29 Mar 2017 16:46:57 -0000

Yes. The results are almost identical.

tjDecompress2 takes more time to execute if called after a delay

Ahmed Faraz — Wed, 29 Mar 2017 16:44:40 -0000

have you tried runinng the code after removing the usleep(50000) statement and then compared the results.
Thanks

tjDecompress2 takes more time to execute if called after a delay

DRC — Wed, 29 Mar 2017 16:25:51 -0000

No idea, because I can't reproduce the behavior using a similarly-sized image. I'm attaching the full source code for the test program I am using, which is based on your code above. In my testing, the second and subsequent iterations are a few ms faster, which is expected behavior (due to caching.)

tjDecompress2 takes more time to execute if called after a delay

Ahmed Faraz — Wed, 29 Mar 2017 09:41:11 -0000

for(int i=0; i<500; i++)
{
unsigned char* _compressedImage = source;
int jpegSubsamp, width, height;
tjhandle _jpegDecompressor = tjInitDecompress();
tjDecompressHeader2(_jpegDecompressor, _compressedImage, fileSize, &width, &height, &jpegSubsamp);
unsigned char dstBuffer[widthheight3]; //!< will contain the decompressed image
    unsigned long long t1 = GetTime();

    tjDecompress2(_jpegDecompressor, _compressedImage, fileSize, dstBuffer, width, 0/*pitch*/, height, TJPF_RGB, TJFLAG_FASTDCT);

    unsigned long long t2 = GetTime();
    printf("TimeTaken: %llu microseconds for %f ms\n", t2-t1,(float)((t2-t1)/(1000)));

   tjDestroy(_jpegDecompressor);    
    usleep(50000);   
}
The above mentioned code is written to test the perfomance of libjpeg-turbo on my system
it decodes a jpeg image repeatedly in a for loop. On my system tjDecompress2 takes around 5-7ms to decode a 1024x768 image. The issue is that if I add a usleep(50000); command at the end of the loop the execution time for tjDecompressHeader2 increases to 25-28ms. What is the reason for this behaviour and how it can be fixed.

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tjDecompress2 takes more time to execute if called after a delay