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How to decode audio via FFmpeg in Android

由 [亡魂溺海] 提交于 2019-11-30 07:44:33

Use audiotrack class to do the work for you. You can do something like this.

JAVA side.

            AudioTrack track;

            int bufSize = AudioTrack.getMinBufferSize(44100,                                AudioFormat.CHANNEL_CONFIGURATION_MONO, 
                            AudioFormat.ENCODING_PCM_16BIT);


            track = new AudioTrack(AudioManager.STREAM_MUSIC, 44100, AudioFormat.CHANNEL_CONFIGURATION_MONO, 
                        AudioFormat.ENCODING_PCM_16BIT, bufSize, AudioTrack.MODE_STREAM);

            track.play(); 

            while(true){
            readBufferFromNative(); //update buffer from native code

                    ....................
                    ....................
                    }

On native Side : You need to read the frames and convert them into raw pcm format first and then start filling the audio buffer continuously. When the buffer is full, it will automatically play.

JNIEXPORT int JNICALL Java_com_ffmpeg_Main_jniMainEntry(JNIEnv* env, jobject obj, jstring input) {

    const char * pszFileName = (*env)->GetStringUTFChars(env, input, 0);
    AVFormatContext * m_fc;
    int err;
    AVPacket pkt;
    char * pAudioBuffer = (char *) av_malloc (AVCODEC_MAX_AUDIO_FRAME_SIZE * 2);
    int i;

    avcodec_register_all ();
    avdevice_register_all ();
    av_register_all ();

    err = av_open_input_file(&m_fc, pszFileName, 0, 0, 0);
    err = av_find_stream_info(m_fc);
    for(i = 0; i<m_fc->nb_streams; i++) {
    if((m_fc->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) || (m_fc->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO)) {
    AVCodec *codec = avcodec_find_decoder(m_fc->streams[i]->codec->codec_id);

    if (codec == 0)
            continue;
    err = avcodec_open(m_fc->streams[i]->codec, codec);
    if (err <0)
            continue;
    }
 }
    while (av_read_frame(m_fc, &pkt)>= 0) {
            if (m_fc-> streams[pkt.stream_index]->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
                    int data_size = AVCODEC_MAX_AUDIO_FRAME_SIZE * 2;
                    int size=pkt->size;
                    while(size > 0) {
                            int len = avcodec_decode_audio3(m_fc->streams[pkt.stream_index]->codec, (int16_t *) pAudioBuffer, &data_size, &pkt);
                            LOGD("data_size %d len %d", data_size, len);
                            size = pkt->size-len;
                            }
            }
 }

}

I could not post a comment, so am posting this as an answer.

I'm also trying to do play aac audio using ffmpeg but have a lot of questions on how to get it working.

I tried using http://code.google.com/p/aacplayer-android/ as a reference, but the author of the code is not using avcodec_decode_audio3 for decoding. The playback through AudioTrack stutters a lot and I assume that the buffer is not getting filled by the decoder fast enough for the audiotrack to play.

Is there any other way I can do this?

Once again, sorry for posting this as a answer.

标签
android
audio
ffmpeg
decode
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