commit a3bb9a3a25b58669d75da4f73764ac4c2bf34158
author Andy Hung <hunga@google.com> Mon Feb 10 15:00:16 2014 -0800
committer Andy Hung <hunga@google.com> Tue Feb 11 13:41:27 2014 -0800
tree b918f7d8be8ebd75106e6ede3fab9102edc5eedb
parent c99144dd2766c499701a7bd7db2d9d8697127186

Proper adjustment of filterlength for downsampling

Bug: 12963040
Change-Id: I772b8efd3f7eae6d075994b210dd0168f5365f4d
Signed-off-by: Andy Hung <hunga@google.com>

services/audioflinger/AudioResamplerDyn.cpp

diff --git a/services/audioflinger/AudioResamplerDyn.cpp b/services/audioflinger/AudioResamplerDyn.cpp
index cd67df5..54c2309 100644
--- a/services/audioflinger/AudioResamplerDyn.cpp
+++ b/services/audioflinger/AudioResamplerDyn.cpp
@@ -283,17 +283,25 @@
             // 32b coefficients, 64 length
             useS32 = true;
             stopBandAtten = 98.;
-            halfLength = 32;
+            if (inSampleRate >= mSampleRate * 4) {
+                halfLength = 48;
+            } else if (inSampleRate >= mSampleRate * 2) {
+                halfLength = 40;
+            } else {
+                halfLength = 32;
+            }
         } else if (mFilterQuality == DYN_LOW_QUALITY) {
             // 16b coefficients, 16-32 length
             useS32 = false;
             stopBandAtten = 80.;
-            if (mSampleRate >= inSampleRate * 2) {
+            if (inSampleRate >= mSampleRate * 4) {
+                halfLength = 24;
+            } else if (inSampleRate >= mSampleRate * 2) {
                 halfLength = 16;
             } else {
                 halfLength = 8;
             }
-            if (mSampleRate >= inSampleRate) {
+            if (inSampleRate <= mSampleRate) {
                 tbwCheat = 1.05;
             } else {
                 tbwCheat = 1.03;
@@ -303,14 +311,14 @@
             // note: > 64 length filters with 16b coefs can have quantization noise problems
             useS32 = false;
             stopBandAtten = 84.;
-            if (mSampleRate >= inSampleRate * 4) {
+            if (inSampleRate >= mSampleRate * 4) {
                 halfLength = 32;
-            } else if (mSampleRate >= inSampleRate * 2) {
+            } else if (inSampleRate >= mSampleRate * 2) {
                 halfLength = 24;
             } else {
                 halfLength = 16;
             }
-            if (mSampleRate >= inSampleRate) {
+            if (inSampleRate <= mSampleRate) {
                 tbwCheat = 1.03;
             } else {
                 tbwCheat = 1.01;