Issue #9: added an app for profiling ARGB => BGRA conversions

src/tests/rgbswap/profile_argb_to_bgra.cpp

@@ -0,0 +1,125 @@
+#include <cstdlib>
+#include <chrono>
+#include <iostream>
+#include <cstring>
+#include <algorithm>
+#ifdef USE_FFMPEG
+extern "C" {
+#include <libswscale/swscale.h>
+}
+#endif
+
+using namespace std;
+using namespace std::chrono;
+
+template<typename T>
+void copy_strided(T begin , T end, T dest, int length)
+{
+    int num_copied = 0;
+    copy_if(begin, end, dest, [&num_copied,length]( double x )
+    {
+        return (num_copied++ % length == 0);
+    }
+    );
+}
+
+bool argb_same_as_bgra(const unsigned char *argb,
+                       const unsigned char *bgra,
+                       size_t l)
+{
+    for (size_t i = 0; i < l; i += 4)
+        if (argb[i] != bgra[i+3] or argb[i+1] != bgra[i+2] or
+            argb[i+2] != bgra[i+1] or argb[i+3] != bgra[i])
+            return false;
+    return true;
+}
+
+int main(int argc, char *argv[])
+{
+    // ARGB with random values
+    size_t w = 1920, h = 1080;
+    if (argc >= 3)
+    {
+        w = atoi(argv[1]);
+        h = atoi(argv[2]);
+    }
+    cout << "Profiling ARGB => BGRA conversion for "
+         << w << " x " << h << " image" << endl;
+    size_t l = 4 * w * h;
+    unsigned char *argb = nullptr;
+    argb = reinterpret_cast<unsigned char *>(malloc(l * sizeof(unsigned char)));
+    for (size_t i = 0; i < l; i++)
+    {
+        argb[i] = i % 32;
+        argb[i+1] = argb[i] * 4;
+        argb[i+2] = i % 256;
+        argb[i+3] = 255;
+    }
+
+    // ARGB => BGRA in a strided loop
+    unsigned char *bgra_loop = nullptr;
+    bgra_loop = reinterpret_cast<unsigned char *>(malloc(l * sizeof(unsigned char)));
+    high_resolution_clock::time_point t1 = high_resolution_clock::now();
+    for (size_t i = 0; i < l; i += 4)
+    {
+        bgra_loop[i] = argb[i+3];
+        bgra_loop[i+1] = argb[i+2];
+        bgra_loop[i+2] = argb[i+1];
+        bgra_loop[i+3] = argb[i];
+    }
+    high_resolution_clock::time_point t2 = high_resolution_clock::now();
+    auto duration = duration_cast<microseconds>( t2 - t1 ).count();
+    cout << "Loop (" << (argb_same_as_bgra(argb, bgra_loop, l) ? "success" : "failure")
+         << ") took: " << duration << " usec" << endl;
+    free(bgra_loop);
+
+    // simple memcopy (no ARGB => BGRA)
+    unsigned char *argb_memcpy = nullptr;
+    argb_memcpy = reinterpret_cast<unsigned char *>(malloc(l * sizeof(unsigned char)));
+    t1 = high_resolution_clock::now();
+    memcpy(argb, argb_memcpy, l * sizeof(unsigned char));
+    t2 = high_resolution_clock::now();
+    duration = duration_cast<microseconds>( t2 - t1 ).count();
+    cout << "memcpy took: " << duration << " usec" << endl;
+    free(argb_memcpy);
+
+    // ARGB => BGRA with a functor
+    unsigned char *bgra_functor = nullptr;
+    bgra_functor = reinterpret_cast<unsigned char *>(malloc(l * sizeof(unsigned char)));
+    t1 = high_resolution_clock::now();
+    copy_strided(argb + 3, argb + l, bgra_functor, 4);
+    copy_strided(argb + 2, argb + l, bgra_functor + 1, 4);
+    copy_strided(argb + 1, argb + l, bgra_functor + 2, 4);
+    copy_strided(argb, argb + l, bgra_functor + 3, 4);
+    t2 = high_resolution_clock::now();
+    duration = duration_cast<microseconds>( t2 - t1 ).count();
+    cout << "functor (" << (argb_same_as_bgra(argb, bgra_functor, l) ? "success" : "failure")
+         << ") took: " << duration << " usec" << endl;
+    free(bgra_functor);
+
+#ifdef USE_FFMPEG
+    // ARGB => BGRA using FFmpeg
+    unsigned char *bgra_ffmpeg = nullptr;
+    bgra_ffmpeg = reinterpret_cast<unsigned char *>(malloc(l * sizeof(unsigned char)));
+    unsigned char *srcSlice[] = {argb};
+    int srcStride[] = {4};
+    int srcSliceY = 0;
+    int srcSliceH = h;
+    unsigned char *dst[] = {bgra_ffmpeg};
+    int dstStride[] = {4};
+    int srcW = w, srcH = h, dstW = w, dstH = h;
+    AVPixelFormat srcFormat = AV_PIX_FMT_ARGB, dstFormat = AV_PIX_FMT_BGRA;
+    SwsContext *c = sws_getCachedContext(nullptr, srcW, srcH, srcFormat, dstW, dstH, dstFormat, 0, nullptr, nullptr, nullptr);
+    t1 = high_resolution_clock::now();
+    sws_scale(c, srcSlice, srcStride, srcSliceY, srcSliceH, dst, dstStride);
+    t2 = high_resolution_clock::now();
+    duration = duration_cast<microseconds>( t2 - t1 ).count();
+    cout << "ffmpeg (" << (argb_same_as_bgra(argb, bgra_ffmpeg, l) ? "success" : "failure")
+         << ") took: " << duration << " usec" << endl;
+    free(bgra_ffmpeg);
+#endif
+
+    // free all memory
+    free(argb);
+    return EXIT_SUCCESS;
+}