Changeset 3351Tweet

Timestamp:

Jan 16, 2009, 3:23:14 PM (14 years ago)

Author:

Sam Hocevar

Message:

storyboard.c:

• generate smaller thumbnail mosaics
• process more images (1 out of 15 instead of 20)
• try to rule out more similar images
• cope with streams that do not advertise their picture size in the headers

File:

• libpipi/trunk/examples/storyboard.c (modified) (7 diffs)

libpipi/trunk/examples/storyboard.c

@@ -25 +25 @@
 #include <pipi.h>
 
-#define STEP 20
+#define STEP 15
 
 #define TWIDTH 90
 #define THEIGHT 60
 #define TCOLS 10
-#define TROWS 200
+#define TROWS 50
 #define NTHUMBS (TCOLS*TROWS)
+
+static int similar(uint8_t *img1, uint8_t *img2);
 
 int main(int argc, char *argv[])
@@ -41 +43 @@
     AVCodec *codec;
     AVFrame *frame;
-    struct SwsContext *sws;
+    struct SwsContext *sws = NULL;
     pipi_image_t *image;
     pipi_pixels_t *p;
@@ -84 +86 @@
     frame = avcodec_alloc_frame();
 
-    sws = sws_getContext(ctx->width, ctx->height, ctx->pix_fmt,
-                         TWIDTH, THEIGHT, PIX_FMT_RGB32,
-                         SWS_BICUBIC, NULL, NULL, NULL);
-
     for(;;)
     {
@@ -96 +94 @@
         if(idx == NTHUMBS || (idx > 0 && ret < 0))
         {
-            /* Only process every 20th image */
             char buf[1024];
             sprintf(buf, fmtstr, k++);
@@ -121 +118 @@
         }
 
-        n++;
-
-        if((n % STEP) == STEP / 2)
-        {
+        /* Only process every 20th image */
+        if((++n % STEP) == STEP / 2)
+        {
+            uint8_t *start;
             int pitch = TWIDTH * TCOLS * 4;
-            uint8_t *start;
+            int good = 1;
 
             start = buffer + (idx % TCOLS) * TWIDTH * 4
                            + (idx / TCOLS) * TWIDTH * TCOLS * 4 * THEIGHT;
 
+            if(!sws)
+                sws = sws_getContext(ctx->width, ctx->height, ctx->pix_fmt,
+                                     TWIDTH, THEIGHT, PIX_FMT_RGB32,
+                                     SWS_BICUBIC, NULL, NULL, NULL);
+
             sws_scale(sws, frame->data, frame->linesize, 0, ctx->height,
                       &start, &pitch);
 
-            /* Now check whether the new image is really different
-             * from the previous one (> 8% pixel changes) */
-            if(idx == 0)
-            {
-                idx++;
-            }
-            else
+            if(idx > 0)
             {
                 uint8_t *prev;
-                int x, y, t, a, b, changed = 0;
 
                 if(idx % TCOLS)
@@ -151 +146 @@
                                  - TWIDTH * TCOLS * 4 * THEIGHT;
 
-                for(y = 0; y < THEIGHT; y++)
-                    for(x = 0; x < TWIDTH; x++)
-                    {
-                        int ok = 0;
-
-                        for(t = 0; t < 3; t++)
-                        {
-                            int offset = y * TWIDTH * TCOLS + x;
-                            a = start[offset * 4 + t];
-                            b = prev[offset * 4 + t];
-
-                            if(a < b - 5 || a > b + 5)
-                            {
-                                ok = 1;
-                                break;
-                            }
-                        }
-
-                        changed += ok;
-                    }
-
-                if(changed > TWIDTH * THEIGHT * 8 / 100)
-                    idx++;
+                /* Now check whether the new image is really different
+                 * from the previous one (> 10% pixel changes) */
+                if(similar(start, prev))
+                    good = 0;
+            }
+
+            if(good)
+            {
+                idx++;
             }
         }
@@ -183 +164 @@
 }
 
+static int similar(uint8_t *img1, uint8_t *img2)
+{
+    int x, y, t, a, b, changed = 0;
+
+    for(y = 1; y < THEIGHT - 1; y++)
+        for(x = 1; x < TWIDTH - 1; x++)
+        {
+            int offset = y * TWIDTH * TCOLS + x;
+            int ok = 0;
+
+            for(t = 0; t < 3; t++)
+            {
+                a = 2 * img1[offset * 4 + t];
+                a += img1[(offset - TWIDTH * TCOLS - 1) * 4 + t];
+                a += img1[(offset - TWIDTH * TCOLS) * 4 + t];
+                a += img1[(offset - TWIDTH * TCOLS + 1) * 4 + t];
+                a += img1[(offset - 1) * 4 + t];
+                a += img1[(offset + 1) * 4 + t];
+                a += img1[(offset + TWIDTH * TCOLS - 1) * 4 + t];
+                a += img1[(offset + TWIDTH * TCOLS) * 4 + t];
+                a += img1[(offset + TWIDTH * TCOLS + 1) * 4 + t];
+                a /= 10;
+
+                b = 2 * img2[offset * 4 + t];
+                b += img2[(offset - TWIDTH * TCOLS - 1) * 4 + t];
+                b += img2[(offset - TWIDTH * TCOLS) * 4 + t];
+                b += img2[(offset - TWIDTH * TCOLS + 1) * 4 + t];
+                b += img2[(offset - 1) * 4 + t];
+                b += img2[(offset + 1) * 4 + t];
+                b += img2[(offset + TWIDTH * TCOLS - 1) * 4 + t];
+                b += img2[(offset + TWIDTH * TCOLS) * 4 + t];
+                b += img2[(offset + TWIDTH * TCOLS + 1) * 4 + t];
+                b /= 10;
+
+                if(a < b - 8 || a > b + 8)
+                {
+                    ok = 1;
+                    break;
+                }
+            }
+
+            changed += ok;
+        }
+
+    return changed < (TWIDTH * THEIGHT * 10 / 100);
+}
+