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copied!<p>My guess: you are doing something wrong. I've just compared libjpeg-turbo with gdk.PixbufLoader and found virtually no speed differences. The code I used is below.</p> <p>For the libjpeg-turbo (jpegload.c):</p> <pre><code>#include <assert.h> #include <stdio.h> #include <stdlib.h> #include <sys/time.h> #include <jpeglib.h> void decompress(FILE* fd) { JSAMPARRAY buffer; int row_stride; struct jpeg_decompress_struct cinfo; struct jpeg_error_mgr jerr; cinfo.err = jpeg_std_error(&jerr); jpeg_create_decompress(&cinfo); jpeg_stdio_src(&cinfo, fd); jpeg_read_header(&cinfo, TRUE); jpeg_start_decompress(&cinfo); row_stride = cinfo.output_width * cinfo.output_components; buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1); while (cinfo.output_scanline < cinfo.output_height) { (void) jpeg_read_scanlines(&cinfo, buffer, 1); } jpeg_finish_decompress(&cinfo); jpeg_destroy_decompress(&cinfo); } int main(int argc, char** argv) { long len; FILE *fd; unsigned char *buf; struct timeval start, end; int i; const int N = 100; int delta; /* read file to cache it in memory */ assert(argc == 2); fd = fopen(argv[1], "rb"); fseek(fd, 0, SEEK_END); len = ftell(fd); rewind(fd); buf = malloc(len); assert(buf != NULL); assert(fread(buf, 1, len, fd) == len); gettimeofday(&start, NULL); for(i = 0; i < N; i++) { rewind(fd); decompress(fd); } gettimeofday(&end, NULL); if(end.tv_sec > start.tv_sec) { delta = (end.tv_sec - start.tv_sec - 1) * 1000; end.tv_usec += 1000000; } delta += (end.tv_usec - start.tv_usec) / 1000; printf("time spent in decompression: %d msec\n", delta/N); } </code></pre> <p>For python gdk (gdk_load.py):</p> <pre><code>import sys import gtk import time def decompress(data): pbl = gtk.gdk.PixbufLoader() pbl.write(data, len(data)) pbl.close() return pbl.get_pixbuf() data = open(sys.argv[1]).read() N = 100 start = time.time() for i in xrange(N): decompress(data) end = time.time() print "time spent in decompression: %d msec" % int((end - start) * 1000 / N) </code></pre> <p>Test run results:</p> <pre><code>$ gcc jpegload.c -ljpeg $ ./a.out DSC_8450.JPG time spent in decompression: 75 msec $ python gdk_load.py DSC_8450.JPG time spent in decompression: 75 msec $ identify DSC_8450.JPG DSC_8450.JPG JPEG 3008x2000 3008x2000+0+0 8-bit DirectClass 2.626MB 0.000u 0:00.019 </code></pre> <p>EDIT: and another test, using <code>gi.repostiroy</code> this time:</p> <pre><code>import sys import time from gi.repository import GdkPixbuf def decompress(filename): pb = GdkPixbuf.Pixbuf.new_from_file(filename) return pb N = 100 start = time.time() for i in xrange(N): decompress(sys.argv[1]) end = time.time() print "time spent in decompression: %d msec" % int((end - start) * 1000 / N) </code></pre> <p>And results:</p> <pre><code>$ python gi_load.py DSC_8450.JPG time spent in decompression: 74 msec </code></pre> <p>GdkPixbuf.PixbufLoader using gi.repository is really much MUCH slower then "pure" <code>gtk.gdk</code>. Code:</p> <pre><code>import sys import time from gi.repository import GdkPixbuf def decompress(data): pbl = GdkPixbuf.PixbufLoader() pbl.write(data, len(data)) pbl.close() return pbl.get_pixbuf() data = bytearray(open(sys.argv[1]).read()) N = 100 start = time.time() for i in xrange(N): decompress(data) end = time.time() print "time spent in decompression: %d msec" % int((end - start) * 1000 / N) </code></pre> <p>Results:</p> <pre><code>$ python gi_load.py DSC_8450.JPG time spent in decompression: 412 msec </code></pre> <p>But <code>GdkPixbuf.Pixbuf.new_from_file</code> works as fast as pure C version even using <code>gi.repository</code>, so you are still either doing something wrong, or expecting too much.</p>

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