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Commit c54a76cb authored by Lajos Molnar's avatar Lajos Molnar Committed by Android (Google) Code Review
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Merge "MediaCodec: expand documentation on flush/EOS handling and adaptive playback" into lmp-dev

parents 99db6030 479cc543
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+59 −5
Original line number Diff line number Diff line
@@ -94,9 +94,17 @@ import java.util.Map;
 * and {@link #dequeueOutputBuffer} then transfer ownership from the codec
 * to the client.<p>
 * The client is not required to resubmit/release buffers immediately
 * to the codec, the sample code above simply does this for simplicity's sake.<p>
 * to the codec, the sample code above simply does this for simplicity's sake.
 * Nonetheless, it is possible that a codec may hold off on generating
 * output buffers until all outstanding buffers have been
 * released/resubmitted.
 * <p>
 * Once the client has an input buffer available it can fill it with data
 * and submit it it to the codec via a call to {@link #queueInputBuffer}.<p>
 * and submit it it to the codec via a call to {@link #queueInputBuffer}.
 * Do not submit multiple input buffers with the same timestamp (unless
 * it is codec-specific data marked as such using the flag
 * {@link #BUFFER_FLAG_CODEC_CONFIG}).
 * <p>
 * The codec in turn will return an output buffer to the client in response
 * to {@link #dequeueOutputBuffer}. After the output buffer has been processed
 * a call to {@link #releaseOutputBuffer} will return it to the codec.
@@ -128,18 +136,64 @@ import java.util.Map;
 * {@link #queueInputBuffer}. The codec will continue to return output buffers
 * until it eventually signals the end of the output stream by specifying
 * the same flag ({@link #BUFFER_FLAG_END_OF_STREAM}) on the BufferInfo returned in
 * {@link #dequeueOutputBuffer}.
 * {@link #dequeueOutputBuffer}.  Do not submit additional input buffers after
 * signaling the end of the input stream, unless the codec has been flushed,
 * or stopped and restarted.
 * <p>
 * <h3>Seeking &amp; Adaptive Playback Support</h3>
 *
 * You can check if a decoder supports adaptive playback via {@link
 * MediaCodecInfo.CodecCapabilities#isFeatureSupported}.  Adaptive playback
 * is only supported if you configure the codec to decode onto a {@link
 * android.view.Surface}.
 *
 * <h4>For decoders that do not support adaptive playback (including
 * when not decoding onto a Surface)</h4>
 *
 * In order to start decoding data that's not adjacent to previously submitted
 * data (i.e. after a seek) it is necessary to {@link #flush} the decoder.
 * data (i.e. after a seek) <em>one must</em> {@link #flush} the decoder.
 * Any input or output buffers the client may own at the point of the flush are
 * immediately revoked, i.e. after a call to {@link #flush} the client does not
 * own any buffers anymore.
 * <p>
 * It is important that the input data after a flush starts at a suitable
 * stream boundary.  The first frame must be able to be decoded completely on
 * its own (for most codecs this means an I-frame), and that no frames should
 * refer to frames before that first new frame.
 * Note that the format of the data submitted after a flush must not change,
 * flush does not support format discontinuities,
 * for this a full {@link #stop}, {@link #configure}, {@link #start}
 * for this a full {@link #stop}, {@link #configure configure()}, {@link #start}
 * cycle is necessary.
 *
 * <h4>For decoders that support adaptive playback</h4>
 *
 * In order to start decoding data that's not adjacent to previously submitted
 * data (i.e. after a seek) it is <em>not necessary</em> to {@link #flush} the
 * decoder.
 * <p>
 * It is still important that the input data after the discontinuity starts
 * at a suitable stream boundary (e.g. I-frame), and that no new frames refer
 * to frames before the first frame of the new input data segment.
 * <p>
 * For some video formats it is also possible to change the picture size
 * mid-stream.  To do this for H.264, the new Sequence Parameter Set (SPS) and
 * Picture Parameter Set (PPS) values must be packaged together with an
 * Instantaneous Decoder Refresh (IDR) frame in a single buffer, which then
 * can be enqueued as a regular input buffer.
 * The client will receive an {@link #INFO_OUTPUT_FORMAT_CHANGED} return
 * value from {@link #dequeueOutputBuffer dequeueOutputBuffer()} or
 * {@link Callback#onOutputBufferAvailable onOutputBufferAvailable()}
 * just after the picture-size change takes place and before any
 * frames with the new size have been returned.
 * <p>
 * Be careful when calling {@link #flush} shortly after you have changed
 * the picture size.  If you have not received confirmation of the picture
 * size change, you will need to repeat the request for the new picture size.
 * E.g. for H.264 you will need to prepend the PPS/SPS to the new IDR
 * frame to ensure that the codec receives the picture size change request.
 *
 * <h3>States and error handling</h3>
 *
 * <p> During its life, a codec conceptually exists in one of the following states:
 * Initialized, Configured, Executing, Error, Uninitialized, (omitting transitory states
 * between them). When created by one of the factory methods,