Fix for the first two frames on level 3

Level_3/AACoder3.m

@@ -71,15 +71,26 @@ function AACSeq3 = AACoder3(fNameIn, fnameAACoded)
         [frameF(:, 1), TNScoeffsL] = TNS(frameF(:, 1), frameTypes{i+1});
         [frameF(:, 2), TNScoeffsR] = TNS(frameF(:, 2), frameTypes{i+1});
 
-        if i < 2
+        if i == 0
-            % TODO: what happens on the first two frames?
+            SMRL = psycho(...
-            SL = frameF(:, 1);
+                originalAudioData(currFrameStart:currFrameStop, 1), ...
-            SR = frameF(:, 2);
+                frameTypes{i+1}, zeros(2048, 1), zeros(2048, 1));
-            GL = 0;
+            SMRR = psycho(...
-            GR = 0;
+                originalAudioData(currFrameStart:currFrameStop, 2), ...
-            sfcL = 0;
+                frameTypes{i+1}, zeros(2048, 1), zeros(2048, 1));
-            sfcR = 0;
+        elseif i == 1
-            continue;
+            prev1FrameStart = (i - 1) * 1024 + 1;
+            prev1FrameStop = prev1FrameStart + 2047;
+            SMRL = psycho(...
+                originalAudioData(currFrameStart:currFrameStop, 1), ...
+                frameTypes{i+1}, ...
+                originalAudioData(prev1FrameStart:prev1FrameStop, 1), ...
+                zeros(2048, 1));
+            SMRR = psycho(...
+                originalAudioData(currFrameStart:currFrameStop, 2), ...
+                frameTypes{i+1}, ...
+                originalAudioData(prev1FrameStart:prev1FrameStop, 2), ...
+                zeros(2048, 1));
         else
             prev1FrameStart = (i - 1) * 1024 + 1;
             prev1FrameStop = prev1FrameStart + 2047;
@@ -95,9 +106,10 @@ function AACSeq3 = AACoder3(fNameIn, fnameAACoded)
                 frameTypes{i+1}, ...
                 originalAudioData(prev1FrameStart:prev1FrameStop, 2), ...
                 originalAudioData(prev2FrameStart:prev2FrameStop, 2));
+        end
+        
         [SL, sfcL, GL] = AACquantizer(frameF(:, 1), frameTypes{i+1}, SMRL);
         [SR, sfcR, GR] = AACquantizer(frameF(:, 2), frameTypes{i+1}, SMRR);
-        end
         
         TL = 0;
         TR = 0;

Level_3/AACquantizer.m

@@ -35,6 +35,7 @@ function [S, sfc, G] = AACquantizer(frameF, frameType, SMR)
         T(LONG_WINDOW_NUMBER_OF_BANDS, 1) = 0;
         quantCoeff(LONG_WINDOW_NUMBER_OF_BANDS, 1) = 0;
         sfc(LONG_WINDOW_NUMBER_OF_BANDS, 1) = 0;
+        initialQuantCoeff = 16 * log2(max(frameF) ^ (3 / 4) / 8191) / 3;
         for band = 1:LONG_WINDOW_NUMBER_OF_BANDS
             frameWlow = TNSTables.B219a(band, 2) + 1;
             frameWhigh = TNSTables.B219a(band, 3) + 1;
@@ -44,7 +45,7 @@ function [S, sfc, G] = AACquantizer(frameF, frameType, SMR)
 
             % Calculates an initial quantization coefficient and attempts
             % quantization
-            quantCoeff(band) = 16 * log2(max(frameF) ^ (3 / 4) / 8191) / 3;
+            quantCoeff(band) = initialQuantCoeff;
             S(frameWlow:frameWhigh, 1) = sign(subFrameF) .* floor(( ...
                 abs(subFrameF) .* 2 ^ (-quantCoeff(band) / 4)) ...
                 .^ (3 / 4) + 0.4054);
@@ -61,7 +62,6 @@ function [S, sfc, G] = AACquantizer(frameF, frameType, SMR)
             while quantErr < T(band) && (band < 2 || ...
                     (quantCoeff(band) - quantCoeff(band - 1) + 1) <= 60)
                 quantCoeff(band) = quantCoeff(band) + 1;
-
                 S(frameWlow:frameWhigh) = sign(subFrameF) .* round(( ...
                     abs(subFrameF) .* 2 ^ (-quantCoeff(band) / 4)) ...
                     .^ (3 / 4) + 0.4054);
@@ -73,6 +73,13 @@ function [S, sfc, G] = AACquantizer(frameF, frameType, SMR)
                 quantErr = sumsqr(subFrameF - frameFDequant);
             end
             
+            if quantCoeff(band) ~= initialQuantCoeff
+                quantCoeff(band) = quantCoeff(band) - 1;
+                S(frameWlow:frameWhigh) = sign(subFrameF) .* round(( ...
+                    abs(subFrameF) .* 2 ^ (-quantCoeff(band) / 4)) ...
+                    .^ (3 / 4) + 0.4054);
+            end
+
             if band == 1
                 sfc(band) = quantCoeff(band);
             else
@@ -89,6 +96,7 @@ function [S, sfc, G] = AACquantizer(frameF, frameType, SMR)
             currFrameStart = (subFrameIndex - 1) * 128 + 1;
             currFrameStop = currFrameStart + 127;
             subFrame = frameF(currFrameStart:currFrameStop);
+            initialQuantCoeff = 16 * log2(max(subFrame) ^ (3 / 4) / 8191) / 3;
             for band = 1:SHORT_WINDOW_NUMBER_OF_BANDS
                 frameWlow = TNSTables.B219b(band, 2);
                 frameWhigh = TNSTables.B219b(band, 3);
@@ -98,7 +106,7 @@ function [S, sfc, G] = AACquantizer(frameF, frameType, SMR)
 
                 % Calculates an initial quantization coefficient and attempts
                 % quantization
-                quantCoeff(band) = 16 * log2(max(subFrame) ^ (3 / 4) / 8191) / 3;
+                quantCoeff(band) = initialQuantCoeff;
                 S(currFrameStart + frameWlow:currFrameStart + frameWhigh, 1) = sign(subFrameF) .* floor(( ...
                     abs(subFrameF) .* 2 ^ (-quantCoeff(band) / 4)) ...
                     .^ (3 / 4) + 0.4054);
@@ -128,6 +136,13 @@ function [S, sfc, G] = AACquantizer(frameF, frameType, SMR)
                     quantErr = sumsqr(subFrameF - frameFDequant);
                 end
                 
+                if quantCoeff(band) ~= initialQuantCoeff
+                    quantCoeff(band) = quantCoeff(band) - 1;
+                    S(currFrameStart + frameWlow:currFrameStart + frameWhigh) = sign(subFrameF) .* round(( ...
+                        abs(subFrameF) .* 2 ^ (-quantCoeff(band) / 4)) ...
+                        .^ (3 / 4) + 0.4054);
+                end
+                
                 if band == 1
                     sfc(band, subFrameIndex) = quantCoeff(band);
                 else