resampler: add Fastest quality

It will use a bi-linear interpolation.
Also cleanup FullDuplexEcho

2 files changed, 16 insertions, 7 deletions

diff --git a/include/oboe/AudioStreamBuilder.h b/include/oboe/AudioStreamBuilder.h
index 092d1773..4e1dad74 100644
--- a/include/oboe/AudioStreamBuilder.h
+++ b/include/oboe/AudioStreamBuilder.h
@@ -341,12 +341,13 @@ public:
     }
 
     /**
-     * If set to None then Oboe will not do sample rate conversion. But the underlying APIs
-     * might do sample rate conversion. Unfortunately sample rate conversion in Android typically
-     * prevents one from getting a low latency stream. So we can do the conversion in Android
-     * and still get a low latency stream.
+     * Specify the quality of the sample rate converter in Oboe.
      *
-     * Default is SampleRateConversionType::Sinc. TODO currently Linear
+     * If set to None then Oboe will not do sample rate conversion. But then the underlying APIs
+     * might do sample rate conversion, which can prevent one from getting a low latency stream.
+     * If we do the conversion in Oboe then we can still get a low latency stream.
+     *
+     * Default is SampleRateConversionQuality::None
      */
     AudioStreamBuilder *setSampleRateConversionQuality(SampleRateConversionQuality quality) {
         mSampleRateConversionQuality = quality;
diff --git a/include/oboe/Definitions.h b/include/oboe/Definitions.h
index 29fd55d1..b1ea7f13 100644
--- a/include/oboe/Definitions.h
+++ b/include/oboe/Definitions.h
@@ -228,18 +228,26 @@ namespace oboe {
     };
 
     /**
-     * The algorithm used to perform sample rate conversion.
+     * Specifies the quality of the sample rate conversion performed by Oboe.
      * Higher quality will require more CPU load.
+     * Higher quality conversion will probably be implemented using a sinc based resampler.
      */
     enum class SampleRateConversionQuality : int32_t {
         /**
          * No conversion by Oboe. Underlying APIs may still do conversion.
          */
         None,
-
+        /**
+         * Fastest conversion but may not sound great.
+         * This may be implemented using bilinear interpolation.
+         */
+        Fastest,
         Low,
         Medium,
         High,
+        /**
+         * Highest quality conversion, which may be expensive in terms of CPU.
+         */
         Best,
     };