From 7e2f547da83f9b00d516958f85a9152d237343a3 Mon Sep 17 00:00:00 2001 From: Hangyu Kuang Date: Wed, 15 Feb 2017 16:15:59 -0800 Subject: [PATCH] media: Update MediaMuxer Java doc to reflect new features. Generated a table to summarizes the feature support in different API version and containers. Features include: Muxing B-frame, 3GP container, multiple video/audio tracks, metadata tracks. Test: None as just documentation. Bug: 28536560 Change-Id: I7ab883a46f4b3420542eae504a33d4ebe1176a65 --- media/java/android/media/MediaMuxer.java | 181 ++++++++++++++++++++++- 1 file changed, 178 insertions(+), 3 deletions(-) diff --git a/media/java/android/media/MediaMuxer.java b/media/java/android/media/MediaMuxer.java index 80832f8a29778..aacce917d910b 100644 --- a/media/java/android/media/MediaMuxer.java +++ b/media/java/android/media/MediaMuxer.java @@ -32,9 +32,8 @@ import java.nio.ByteBuffer; import java.util.Map; /** - * MediaMuxer facilitates muxing elementary streams. Currently supports mp4 or - * webm file as the output and at most one audio and/or one video elementary - * stream. MediaMuxer does not support muxing B-frames. + * MediaMuxer facilitates muxing elementary streams. Currently MediaMuxer supports MP4, Webm + * and 3GP file as the output. It also supports muxing B-frames in MP4 since Android Nougat. *

* It is generally used like this: * @@ -65,6 +64,182 @@ import java.util.Map; * muxer.stop(); * muxer.release(); * + * + +

Metadata Track

+

+ Metadata is usefule in carrying extra information that correlated with video or audio to + facilate offline processing, e.g. gyro signals from the sensor. Meatadata track is only + supported in MP4 format. When adding a metadata track, track's mime format must start with + prefix "application/", e.g. "applicaton/gyro". Metadata's format/layout will be defined by + the application. The generated MP4 file uses TextMetaDataSampleEntry defined in section 12.3.3.2 + of the ISOBMFF to signal the metadata's mime format. When using {@link android.media.MediaExtractor} + to extract the file with metadata track, the mime format of the metadata will be extracted into + {@link android.media.MediaFormat}. + + 

+   MediaMuxer muxer = new MediaMuxer("temp.mp4", OutputFormat.MUXER_OUTPUT_MPEG_4);
+   // More often, the MediaFormat will be retrieved from MediaCodec.getOutputFormat()
+   // or MediaExtractor.getTrackFormat().
+   MediaFormat audioFormat = new MediaFormat(...);
+   MediaFormat videoFormat = new MediaFormat(...);
+
+   // Setup Metadata Track
+   MediaFormat metadataFormat = new MediaFormat(...);
+   metadataFormat.setString(KEY_MIME, "application/gyro");
+
+   int audioTrackIndex = muxer.addTrack(audioFormat);
+   int videoTrackIndex = muxer.addTrack(videoFormat);
+   int metadataTrackIndex = muxer.addTrack(metadataFormat);
+   ByteBuffer inputBuffer = ByteBuffer.allocate(bufferSize);
+   boolean finished = false;
+   BufferInfo bufferInfo = new BufferInfo();
+
+   muxer.start();
+   while(!finished) {
+     // getInputBuffer() will fill the inputBuffer with one frame of encoded
+     // sample from either MediaCodec or MediaExtractor, set isAudioSample to
+     // true when the sample is audio data, set up all the fields of bufferInfo,
+     // and return true if there are no more samples.
+     finished = getInputBuffer(inputBuffer, sampleType, bufferInfo);
+     if (!finished) {
+       int currentTrackIndex = getTrackIndex(sampleType);
+       muxer.writeSampleData(currentTrackIndex, inputBuffer, bufferInfo);
+     }
+   };
+   muxer.stop();
+   muxer.release();
+ }
+ +

Features and API History

+

+ The following table summarizes the feature support in different API version and containers. + For API version numbers, see {@link android.os.Build.VERSION_CODES}. + + + + + + + + + + + + + + + + +
SymbolMeaning
●Supported
○Not supported
▧Supported in MP4/WebM/3GP
⁕Only Supported in MP4
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
FeatureSDK Version
181920212223242526+
MP4 container●●●●●●●●●
WebM container○○○●●●●●●
3GP container○○○○○○○○●
Muxing B-Frames(bi-directional predicted frames)○○○○○○⁕⁕⁕
Muxing Single Video/Audio Track▧▧▧▧▧▧▧▧▧
Muxing Multiple Video/Audio Tracks○○○○○○○○⁕
Muxing Metadata Tracks○○○○○○○○⁕
*/ final public class MediaMuxer {