commit cc6bc4b383f5112b34962fe6a51ac64f1778a8bf
author Andy Hung <hunga@google.com> Wed Jan 09 18:42:41 2019 -0800
committer Andy Hung <hunga@google.com> Fri Apr 26 15:34:57 2019 -0700
tree 3dcc436f5376840e1dd134a8904b8f7b831875fc
parent f58e51b4e37cb719291ebe7b9f8970bc42e3767d

MediaCodec: Fix documentation on float raw audio buffers

Test: make docs, check html
Bug: 131423214
Change-Id: If2d6f78cc5f77a5c7b5b8b936ae9f3216387561e

media/java/android/media/MediaCodec.java

diff --git a/media/java/android/media/MediaCodec.java b/media/java/android/media/MediaCodec.java
index c6c2fdd..c09bd79 100644
--- a/media/java/android/media/MediaCodec.java
+++ b/media/java/android/media/MediaCodec.java
@@ -89,15 +89,33 @@
  <h4>Raw Audio Buffers</h4>
  <p>
  Raw audio buffers contain entire frames of PCM audio data, which is one sample for each channel
- in channel order. Each sample is a {@linkplain AudioFormat#ENCODING_PCM_16BIT 16-bit signed
- integer in native byte order}.
+ in channel order. Each PCM audio sample is either a 16 bit signed integer or a float,
+ in native byte order.
+ Raw audio buffers in the float PCM encoding are only possible
+ if the MediaFormat's {@linkplain MediaFormat#KEY_PCM_ENCODING}
+ is set to {@linkplain AudioFormat#ENCODING_PCM_FLOAT} during MediaCodec
+ {@link #configure configure(&hellip;)}
+ and confirmed by {@link #getOutputFormat} for decoders
+ or {@link #getInputFormat} for encoders.
+ A sample method to check for float PCM in the MediaFormat is as follows:
 
  <pre class=prettyprint>
+ static boolean isPcmFloat(MediaFormat format) {
+   return format.getInteger(MediaFormat.KEY_PCM_ENCODING, AudioFormat.ENCODING_PCM_16BIT)
+       == AudioFormat.ENCODING_PCM_FLOAT;
+ }</pre>
+
+ In order to extract, in a short array,
+ one channel of a buffer containing 16 bit signed integer audio data,
+ the following code may be used:
+
+ <pre class=prettyprint>
+ // Assumes the buffer PCM encoding is 16 bit.
  short[] getSamplesForChannel(MediaCodec codec, int bufferId, int channelIx) {
    ByteBuffer outputBuffer = codec.getOutputBuffer(bufferId);
    MediaFormat format = codec.getOutputFormat(bufferId);
    ShortBuffer samples = outputBuffer.order(ByteOrder.nativeOrder()).asShortBuffer();
-   int numChannels = formet.getInteger(MediaFormat.KEY_CHANNEL_COUNT);
+   int numChannels = format.getInteger(MediaFormat.KEY_CHANNEL_COUNT);
    if (channelIx &lt; 0 || channelIx &gt;= numChannels) {
      return null;
    }