1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16package com.google.android.exoplayer2.ext.ffmpeg;
17
18import android.content.Context;
19import android.content.pm.PackageManager;
20import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
21import com.google.android.exoplayer2.decoder.SimpleOutputBuffer;
22import com.google.android.exoplayer2.util.MimeTypes;
23import com.android.tv.common.SoftPreconditions;
24
25import java.nio.ByteBuffer;
26
27/**
28 * Audio decoder which uses ffmpeg extension of ExoPlayer2. Since {@link FfmpegDecoder} is package
29 * private, expose the decoder via this class. Supported formats are AC3 and MP2.
30 */
31public class FfmpegAudioDecoder {
32    private static final int NUM_DECODER_BUFFERS = 1;
33
34    // The largest AC3 sample size. This is bigger than the largest MP2 sample size (1729).
35    private static final int INITIAL_INPUT_BUFFER_SIZE = 2560;
36    private static boolean AVAILABLE;
37
38    static {
39        AVAILABLE =
40                FfmpegLibrary.supportsFormat(MimeTypes.AUDIO_AC3)
41                        && FfmpegLibrary.supportsFormat(MimeTypes.AUDIO_MPEG_L2);
42    }
43
44    private FfmpegDecoder mDecoder;
45    private DecoderInputBuffer mInputBuffer;
46    private SimpleOutputBuffer mOutputBuffer;
47    private boolean mStarted;
48
49    /** Return whether Ffmpeg based software audio decoder is available. */
50    public static boolean isAvailable() {
51        return AVAILABLE;
52    }
53
54    /** Creates an Ffmpeg based software audio decoder. */
55    public FfmpegAudioDecoder(Context context) {
56        if (context.checkSelfPermission("android.permission.INTERNET")
57                == PackageManager.PERMISSION_GRANTED) {
58            throw new IllegalStateException("This code should run in an isolated process");
59        }
60    }
61
62    /**
63     * Decodes an audio sample.
64     *
65     * @param timeUs presentation timestamp of the sample
66     * @param sample data
67     */
68    public void decode(long timeUs, byte[] sample) {
69        SoftPreconditions.checkState(AVAILABLE);
70        mInputBuffer.data.clear();
71        mInputBuffer.data.put(sample);
72        mInputBuffer.data.flip();
73        mInputBuffer.timeUs = timeUs;
74        mDecoder.decode(mInputBuffer, mOutputBuffer, !mStarted);
75        if (!mStarted) {
76            mStarted = true;
77        }
78    }
79
80    /** Returns a decoded sample from decoder. */
81    public ByteBuffer getDecodedSample() {
82        return mOutputBuffer.data;
83    }
84
85    /** Returns the presentation time for the decoded sample. */
86    public long getDecodedTimeUs() {
87        return mOutputBuffer.timeUs;
88    }
89
90    /**
91     * Clear previous decode state if any. Prepares to decode samples of the specified encoding.
92     * This method should be called before using decode.
93     *
94     * @param mime audio encoding
95     */
96    public void resetDecoderState(String mime) {
97        SoftPreconditions.checkState(AVAILABLE);
98        release();
99        try {
100            mDecoder =
101                    new FfmpegDecoder(
102                            NUM_DECODER_BUFFERS,
103                            NUM_DECODER_BUFFERS,
104                            INITIAL_INPUT_BUFFER_SIZE,
105                            mime,
106                            null);
107            mStarted = false;
108            mInputBuffer = mDecoder.createInputBuffer();
109            // Since native JNI requires direct buffer, we should allocate it by #allocateDirect.
110            mInputBuffer.data = ByteBuffer.allocateDirect(INITIAL_INPUT_BUFFER_SIZE);
111            mOutputBuffer = mDecoder.createOutputBuffer();
112        } catch (FfmpegDecoderException e) {
113            // if AVAILABLE is {@code true}, this will not happen.
114        }
115    }
116
117    /** Releases all the resource. */
118    public void release() {
119        SoftPreconditions.checkState(AVAILABLE);
120        if (mDecoder != null) {
121            mDecoder.release();
122            mInputBuffer = null;
123            mOutputBuffer = null;
124            mDecoder = null;
125        }
126    }
127}
128