Norimasa Okamoto / BaseJpegDecode

huffmancode to decode in real-time for motion-jpeg

Dependents:   BaseJpegDecode_example SimpleJpegDecode_example Dumb_box_rev2

example code:

Import programBaseJpegDecode_example

BaseJpegDeocde exampe program

Last commit 27 Jan 2013 by Norimasa Okamoto

Import programSimpleJpegDecode_example

convert JPEG stream data to bitmap, BaseJpegDecode example program

Last commit 02 Feb 2013 by Norimasa Okamoto

Diff: aanIDCT.cpp

Revision:
6:d7ee458cacd1
Parent:
3:a7547692071d
--- a/aanIDCT.cpp	Sun Jan 27 11:00:50 2013 +0000
+++ b/aanIDCT.cpp	Sat Feb 02 01:18:15 2013 +0000
@@ -1,4 +1,4 @@
-// aanIDCT.cpp
+// aanIDCT.cpp 2013/2/1
 // based: http://www.ijg.org/ libjpeg(jpeg-8d)jidctfst.c jidctflt.c jidctmgr.c
 #include "mbed.h"
 #include "aanIDCT.h"
@@ -48,6 +48,26 @@
     return DESCALE(x, PASS1_BITS+LOG2_CONST);
 }
 
+#if 1
+int8_t range_limit(int val) {
+    if (val < -128) {
+        return -128;
+    } else if (val > 127) {
+        return 127;
+    }
+    return val;
+}
+#else
+inline int8_t range_limit(int val) {
+    if (val < -128) {
+        return -128;
+    } else if (val > 127) {
+        return 127;
+    }
+    return val;
+}
+#endif
+
 void aanIDCT::conv(int8_t output[], int16_t input[])
 {
     uint16_t* quant = (uint16_t*)aanscales;
@@ -117,7 +137,7 @@
                ws[pos+7] == 0) {
             int dcval = ws[pos+0];
             for(int x = 0; x < DCTSIZE; x++) {
-                output[pos+x] = IDESCALE(dcval);
+                output[pos+x] = range_limit(IDESCALE(dcval));
             }
             continue;
         }
@@ -150,13 +170,13 @@
         int tmp5 = tmp11 - tmp6;
         int tmp4 = tmp10 - tmp5;
 
-        output[pos+0] = IDESCALE(tmp0 + tmp7);
-        output[pos+7] = IDESCALE(tmp0 - tmp7);
-        output[pos+1] = IDESCALE(tmp1 + tmp6);
-        output[pos+6] = IDESCALE(tmp1 - tmp6);
-        output[pos+2] = IDESCALE(tmp2 + tmp5);
-        output[pos+5] = IDESCALE(tmp2 - tmp5);
-        output[pos+3] = IDESCALE(tmp3 + tmp4);
-        output[pos+4] = IDESCALE(tmp3 - tmp4);
+        output[pos+0] = range_limit(IDESCALE(tmp0 + tmp7));
+        output[pos+7] = range_limit(IDESCALE(tmp0 - tmp7));
+        output[pos+1] = range_limit(IDESCALE(tmp1 + tmp6));
+        output[pos+6] = range_limit(IDESCALE(tmp1 - tmp6));
+        output[pos+2] = range_limit(IDESCALE(tmp2 + tmp5));
+        output[pos+5] = range_limit(IDESCALE(tmp2 - tmp5));
+        output[pos+3] = range_limit(IDESCALE(tmp3 + tmp4));
+        output[pos+4] = range_limit(IDESCALE(tmp3 - tmp4));
     }
 }