MediaSync 類別

定義

[Android.Runtime.Register("android/media/MediaSync", ApiSince=23, DoNotGenerateAcw=true)]
public sealed class MediaSync : Java.Lang.Object

[<Android.Runtime.Register("android/media/MediaSync", ApiSince=23, DoNotGenerateAcw=true)>]
type MediaSync = class
    inherit Object

繼承

Object

JavaObject

Object

MediaSync

屬性

RegisterAttribute

備註

MediaSync 類別可用於同步播放音訊與視訊串流。 它也可以用來播放純音訊或純視訊串流。

MediaSync 通常的使用方式如下：

MediaSync sync = new MediaSync();
            sync.setSurface(surface);
            Surface inputSurface = sync.createInputSurface();
            ...
            // MediaCodec videoDecoder = ...;
            videoDecoder.configure(format, inputSurface, ...);
            ...
            sync.setAudioTrack(audioTrack);
            sync.setCallback(new MediaSync.Callback() {
                {@literal @Override}
                public void onAudioBufferConsumed(MediaSync sync, ByteBuffer audioBuffer, int bufferId) {
                    ...
                }
            }, null);
            // This needs to be done since sync is paused on creation.
            sync.setPlaybackParams(new PlaybackParams().setSpeed(1.f));

            for (;;) {
              ...
              // send video frames to surface for rendering, e.g., call
              // videoDecoder.releaseOutputBuffer(videoOutputBufferIx, videoPresentationTimeNs);
              // More details are available as below.
              ...
              sync.queueAudio(audioByteBuffer, bufferId, audioPresentationTimeUs); // non-blocking.
              // The audioByteBuffer and bufferId will be returned via callback.
              // More details are available as below.
              ...
                ...
            }
            sync.setPlaybackParams(new PlaybackParams().setSpeed(0.f));
            sync.release();
            sync = null;

            // The following code snippet illustrates how video/audio raw frames are created by
            // MediaCodec's, how they are fed to MediaSync and how they are returned by MediaSync.
            // This is the callback from MediaCodec.
            onOutputBufferAvailable(MediaCodec codec, int bufferId, BufferInfo info) {
                // ...
                if (codec == videoDecoder) {
                    // surface timestamp must contain media presentation time in nanoseconds.
                    codec.releaseOutputBuffer(bufferId, 1000 * info.presentationTime);
                } else {
                    ByteBuffer audioByteBuffer = codec.getOutputBuffer(bufferId);
                    sync.queueAudio(audioByteBuffer, bufferId, info.presentationTime);
                }
                // ...
            }

            // This is the callback from MediaSync.
            onAudioBufferConsumed(MediaSync sync, ByteBuffer buffer, int bufferId) {
                // ...
                audioDecoder.releaseBuffer(bufferId, false);
                // ...
            }

客戶端需要根據串流類型設定 Surface 和/或 AudioTrack，來設定相應的 sink。

對於影片，客戶端需要呼叫 #createInputSurface 取得一個能渲染影片幀的表面。

對於音訊，用戶端需要正確設定音軌，例如使用 AudioTrack#MODE_STREAM。 音訊緩衝區會直接 #queueAudio透過 傳送到 MediaSync，然後透過 Callback#onAudioBufferConsumed 非同步方式回傳給用戶端。 客戶端不應該修改音訊緩衝區，直到它被回傳。

用戶端可選擇性地預先填充音訊/視訊緩衝區，將播放速率設為 0.0，然後將音訊/視訊緩衝區餵給相應元件。 這可以減少初期可能的欠支。

Java 文件 android.media.MediaSync。

本頁部分內容為基於 Open Source Project 所創建與分享的作品，並依授權條款所描述的使用進行修改。