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New bandwidth settings for DRM, improved quantization quality adaptation (almost constant bit-rate now)

--- a/libfaac/frame.c

+++ b/libfaac/frame.c

@@ -16,7 +16,7 @@

  * License along with this library; if not, write to the Free Software

  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  *

- * $Id: frame.c,v 1.64 2004/07/13 17:56:37 corrados Exp $

+ * $Id: frame.c,v 1.65 2004/07/18 09:34:24 corrados Exp $

  */

 /*

@@ -180,18 +180,23 @@

 			int cutoff;

 		}	rates[] = {

 #ifdef DRM

-            /* DRM needs lower bit-rates. We've chosen higher bandwidth values and

+            /* DRM uses low bit-rates. We've chosen higher bandwidth values and

                decrease the quantizer quality at the same time to preserve the

                low bit-rate */

-            {7000,  1500},

-            {15000, 3000},

-            {23000, 4000},

-#endif

+            {4500,  1200},

+            {9180,  2500},

+            {11640, 3000},

+            {14500, 4000},

+            {17460, 5500},

+            {20960, 6250},

+            {40000, 12000},

+#else

 			{29500, 5000},

 			{37500, 7000},

 			{47000, 10000},

 			{64000, 16000},

 			{76000, 20000},

+#endif

 			{0, 0}

 		};

@@ -199,12 +204,12 @@

 		int r0, r1;

 #ifdef DRM

-        config->quantqual = 40; /* init with a lower value for DRM */

+        double tmpbitRate = (double)config->bitRate;

 #else

-        config->quantqual = 100;

+        double tmpbitRate = (double)config->bitRate * 44100 / hEncoder->sampleRate;

 #endif

-		config->bitRate = (double)config->bitRate * 44100 / hEncoder->sampleRate;

+        config->quantqual = 100;

 		f0 = f1 = rates[0].cutoff;

 		r0 = r1 = rates[0].rate;

@@ -215,25 +220,27 @@

 			f1 = rates[i].cutoff;

 			r0 = r1;

 			r1 = rates[i].rate;

-			if (rates[i].rate >= config->bitRate)

+			if (rates[i].rate >= tmpbitRate)

 				break;

 		}

-		if (config->bitRate > r1)

-			config->bitRate = r1;

-        if (config->bitRate < r0)

-            config->bitRate = r0;

+        if (tmpbitRate > r1)

+            tmpbitRate = r1;

+        if (tmpbitRate < r0)

+            tmpbitRate = r0;

 		if (f1 > f0)

             config->bandWidth =

-                    pow((double)config->bitRate / r1,

+                    pow((double)tmpbitRate / r1,

                     log((double)f1 / f0) / log ((double)r1 / r0)) * (double)f1;

 		else

 			config->bandWidth = f1;

+#ifndef DRM

 		config->bandWidth =

 				(double)config->bandWidth * hEncoder->sampleRate / 44100;

-		config->bitRate = (double)config->bitRate * hEncoder->sampleRate / 44100;

+		config->bitRate = tmpbitRate * hEncoder->sampleRate / 44100;

+#endif

 		if (config->bandWidth > bwbase)

 		  config->bandWidth = bwbase;

@@ -447,6 +454,10 @@

     BitStream *bitStream; /* bitstream used for writing the frame to */

     TnsInfo *tnsInfo_for_LTP;

     TnsInfo *tnsDecInfo;

+#ifdef DRM

+    int desbits, diff;

+    double fix;

+#endif

     /* local copy's of parameters */

     ChannelInfo *channelInfo = hEncoder->channelInfo;

@@ -738,6 +749,12 @@

     MSEncode(coderInfo, channelInfo, hEncoder->freqBuff, numChannels, allowMidside);

+#ifdef DRM

+    /* loop the quantization until the desired bit-rate is reached */

+    diff = 1; /* to enter while loop */

+    hEncoder->aacquantCfg.quality = 120; /* init quality setting */

+    while (diff > 0) { /* if too many bits, do it again */

+#endif

     /* Quantize and code the signal */

     for (channel = 0; channel < numChannels; channel++) {

         if (coderInfo[channel].block_type == ONLY_SHORT_WINDOW) {

@@ -753,6 +770,35 @@

         }

     }

+#ifdef DRM

+    /* Write the AAC bitstream */

+    bitStream = OpenBitStream(bufferSize, outputBuffer);

+    WriteBitstream(hEncoder, coderInfo, channelInfo, bitStream, numChannels);

+

+    /* Close the bitstream and return the number of bytes written */

+    frameBytes = CloseBitStream(bitStream);

+

+    /* now calculate desired bits and compare with actual encoded bits */

+    desbits = (int) ((double) numChannels * (hEncoder->config.bitRate * FRAME_LEN)

+            / hEncoder->sampleRate);

+

+    diff = ((frameBytes - 1 /* CRC */) * 8) - desbits;

+

+    /* do linear correction according to relative difference */

+    fix = (double) desbits / ((frameBytes - 1 /* CRC */) * 8);

+

+    /* speed up convergence. A value of 0.92 gives approx up to 10 iterations */

+    if (fix > 0.92)

+        fix = 0.92;

+

+    hEncoder->aacquantCfg.quality *= fix;

+

+    /* quality should not go lower than 1, set diff to exit loop */

+    if (hEncoder->aacquantCfg.quality <= 1)

+        diff = -1;

+    }

+#endif

+

     // fix max_sfb in CPE mode

     for (channel = 0; channel < numChannels; channel++)

     {

@@ -811,6 +857,7 @@

         }

     }

+#ifndef DRM

     /* Write the AAC bitstream */

     bitStream = OpenBitStream(bufferSize, outputBuffer);

@@ -838,17 +885,11 @@

 			hEncoder->aacquantCfg.quality *= (1.0 - fix);

 			if (hEncoder->aacquantCfg.quality > 300)

 				hEncoder->aacquantCfg.quality = 300;

-#ifdef DRM

-            /* since we have very low bit-rates in DRM, we have to decrease the

-               bandwidth and also decrease the quality */

-            if (hEncoder->aacquantCfg.quality < 10)

-                hEncoder->aacquantCfg.quality = 10;

-#else           

             if (hEncoder->aacquantCfg.quality < 50)

                 hEncoder->aacquantCfg.quality = 50;

-#endif

 		}

     }

+#endif

     return frameBytes;

 }

@@ -1070,6 +1111,9 @@

 /*

 $Log: frame.c,v $

+Revision 1.65  2004/07/18 09:34:24  corrados

+New bandwidth settings for DRM, improved quantization quality adaptation (almost constant bit-rate now)

+

 Revision 1.64  2004/07/13 17:56:37  corrados

 bug fix with new object type definitions