Android NDK开发之旅35--FFmpeg+AudioTrack音频播放
16lz
2021-01-23
Android NDK开发之旅 目录
前言
基于Android NDK开发之旅34--FFmpeg音频解码这篇文章，我们已经学会音频解码基本过程。
音频播放有两种方法：FFmpeg+AudioTrack(Android自带的播放工具) 、FFmpeg+OpenSL ES。
这篇文章就通过FFmpeg+AudioTrack方式对音频解码的文件进行播放操作。
1.Java中 jni声明
package com.haocai.ffmpegtest.util;import android.view.Surface;public class VideoPlayer { //音频播放 public native void audioPlayer(String input); static{ System.loadLibrary("avutil-54"); System.loadLibrary("swresample-1"); System.loadLibrary("avcodec-56"); System.loadLibrary("avformat-56"); System.loadLibrary("swscale-3"); System.loadLibrary("postproc-53"); System.loadLibrary("avfilter-5"); System.loadLibrary("avdevice-56"); System.loadLibrary("myffmpeg"); }}2.定义播放模块AudioTrack
package com.haocai.ffmpegtest.util;import android.media.AudioFormat;import android.media.AudioManager;import android.media.AudioTrack;import android.util.Log;/** * Created by Xionghu on 2017/12/12. * Desc: */public class AudioUtil { //Todo 生成JNI签名后删除 该声明 //Todo 该声明 来源于 audioTrack.write() public int write(byte[] audioData, int offsetInBytes, int sizeInBytes) { return 0; } /** * 创建一个AudioTrack对象，用于播放 * @return */ public AudioTrack createAudioTrack(int sampleRateInHz, int nb_channels){ Log.i("AudioUtil", "nb_channels:"+nb_channels); Log.i("AudioUtil", "sampleRateInHz:"+sampleRateInHz); //固定格式的音频码流 int audioFormat = AudioFormat.ENCODING_PCM_16BIT; //声道个数 影响声道的布局 int channelConfig; if(nb_channels == 1){ channelConfig = android.media.AudioFormat.CHANNEL_OUT_MONO; }else if(nb_channels == 2){ channelConfig = android.media.AudioFormat.CHANNEL_OUT_STEREO; }else{ channelConfig = android.media.AudioFormat.CHANNEL_OUT_STEREO; } int bufferSizeInBytes = AudioTrack.getMinBufferSize(sampleRateInHz, channelConfig, audioFormat); AudioTrack audioTrack = new AudioTrack( AudioManager.STREAM_MUSIC, sampleRateInHz, channelConfig, audioFormat, bufferSizeInBytes, AudioTrack.MODE_STREAM); //audioTrack.write() return audioTrack; }}3.获取播放模块AudioTrack相关方法的签名
3.1Build ->Rebuild Project 得到编译文件classes
3.2通过javap得到方法的签名
Windows 命令模式下
D:\>CD D:\AndroidProject\FFmpegTest\app\build\intermediates\classes\debugD:\AndroidProject\FFmpegTest\app\build\intermediates\classes\debug> javap -s -p com.haocai.ffmpegtest.util.AudioUtilCompiled from "AudioUtil.java"public class com.haocai.ffmpegtest.util.AudioUtil { public com.haocai.ffmpegtest.util.AudioUtil(); descriptor: ()V public int write(byte[], int, int); descriptor: ([BII)I public android.media.AudioTrack createAudioTrack(int, int); descriptor: (II)Landroid/media/AudioTrack;}
获取签名 4.编写音频解码播放功能
ffmpeg_voicer.c
#include #include #include #include #include #include //解码#include "include/libavcodec/avcodec.h"//封装格式处理#include "include/libavformat/avformat.h"//像素处理#include "include/libswscale/swscale.h"//重采样#include "include/libswresample/swresample.h"#define LOG_TAG "ffmpegandroidplayer"#define LOGI(FORMAT,...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,FORMAT,##__VA_ARGS__);#define LOGE(FORMAT,...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,FORMAT,##__VA_ARGS__);#define LOGD(FORMAT,...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,FORMAT, ##__VA_ARGS__)//音频解码 采样率 新版版可达48000 * 4#define MAX_AUDIO_FRME_SIZE 2 * 44100//音频播放JNIEXPORT void JNICALL Java_com_haocai_ffmpegtest_util_VideoPlayer_audioPlayer(JNIEnv *env, jobject jobj, jstring input_jstr) { const char* input_cstr = (*env)->GetStringUTFChars(env, input_jstr, NULL); LOGI("%s", "init"); //注册组件 av_register_all(); AVFormatContext *pFormatCtx = avformat_alloc_context(); //打开音频文件 if (avformat_open_input(&pFormatCtx, input_cstr, NULL, NULL) != 0) { LOGI("%s", "无法打开音频文件"); return; } //获取输入文件信息 if (avformat_find_stream_info(pFormatCtx, NULL) < 0) { LOGI("%s", "无法获取输入文件信息"); return; } //获取音频流索引位置 int i = 0, audio_stream_idx = -1; for (; i < pFormatCtx->nb_streams; i++) { if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO) { audio_stream_idx = i; break; } } if (audio_stream_idx == -1) { LOGI("%s", "找不到音频流"); return; } //获取解码器 AVCodecContext *pCodeCtx = pFormatCtx->streams[audio_stream_idx]->codec; AVCodec *codec = avcodec_find_decoder(pCodeCtx->codec_id); if (codec == NULL) { LOGI("%s", "无法获取加码器"); return; } //打开解码器 if (avcodec_open2(pCodeCtx, codec, NULL) < 0) { LOGI("%s", "无法打开解码器"); return; } //压缩数据 AVPacket *packet = (AVPacket *)av_malloc(sizeof(AVPacket)); //解压缩数据 AVFrame *frame = av_frame_alloc(); //frame->16bit 44100 PCM 统一音频采样格式与采样率 SwrContext *swrCtx = swr_alloc(); //输入采样率格式 enum AVSampleFormat in_sample_fmt = pCodeCtx->sample_fmt; //输出采样率格式16bit PCM enum AVSampleFormat out_sample_fmt = AV_SAMPLE_FMT_S16; //输入采样率 int in_sample_rate = pCodeCtx->sample_rate; //输出采样率 int out_sample_rate = 44100; //获取输入的声道布局 //根据声道个数获取默认的声道布局(2个声道，默认立体声) //av_get_default_channel_layout(pCodeCtx->channels); uint64_t in_ch_layout = pCodeCtx->channel_layout; //输出的声道布局 uint64_t out_ch_layout = AV_CH_LAYOUT_STEREO; swr_alloc_set_opts(swrCtx, out_ch_layout, out_sample_fmt, out_sample_rate, in_ch_layout, in_sample_fmt, in_sample_rate, 0, NULL); swr_init(swrCtx); //获取输入输出的声道个数 int out_channel_nb = av_get_channel_layout_nb_channels(out_ch_layout); LOGI("out_count:%d", out_channel_nb); //jclass player_class = (*env)->GetObjectClass(env,jobj); jclass cls = (*env)->FindClass(env, "com/haocai/ffmpegtest/util/AudioUtil"); //jmethodID jmethodID constructor_mid= (*env)->GetMethodID(env, cls,"","()V"); //实例化一个AudioUtil对象(可以在constructor_mid后加参) jobject audioutil_obj = (*env)->NewObject(env, cls, constructor_mid); //类似于AudioUtil audioutil =new AudioUtil(); //AudioTrack对象 jmethodID create_audio_track_mid =(*env)->GetMethodID(env,cls,"createAudioTrack","(II)Landroid/media/AudioTrack;"); jobject audio_track = (*env)->CallObjectMethod(env,audioutil_obj,create_audio_track_mid,out_sample_rate,out_channel_nb); //调用AudioTrack.play方法 jclass audio_track_class = (*env)->GetObjectClass(env,audio_track); jmethodID audio_track_play_mid = (*env)->GetMethodID(env,audio_track_class,"play","()V"); (*env)->CallVoidMethod(env,audio_track,audio_track_play_mid); //AudioTrack.write jmethodID audio_track_write_mid = (*env)->GetMethodID(env,audio_track_class,"write","([BII)I"); //16bit 44100 PCM 数据 uint8_t *out_buffer = (uint8_t *)av_malloc(MAX_AUDIO_FRME_SIZE); int got_frame = 0, framecount = 0, ret; //6.一帧一帧读取压缩的音频数据AVPacket while (av_read_frame(pFormatCtx, packet) >= 0) { //解码音频类型的Packet， packet 有可能是音频数据流 有可能是视频数据流 if (packet->stream_index == audio_stream_idx) { //解码 ret = avcodec_decode_audio4(pCodeCtx, frame, &got_frame, packet); if (ret < 0) { LOGI("%s", "解码完成"); break; } //非0，正在解码 if (got_frame > 0) { LOGI("解码：%d", framecount++); swr_convert(swrCtx, &out_buffer, MAX_AUDIO_FRME_SIZE, (const uint8_t **)frame->data, frame->nb_samples); //获取sample的size int out_buffer_size = av_samples_get_buffer_size(NULL, out_channel_nb, frame->nb_samples, out_sample_fmt, 1); //out_buffer 缓冲区数据，转换成byte数组 jbyteArray audio_sample_array = (*env)->NewByteArray(env,out_buffer_size); jbyte* sample_byte = (*env)->GetByteArrayElements(env,audio_sample_array,NULL); //将out_buffer的数据复制到sample_byte memcpy(sample_byte,out_buffer,out_buffer_size); //同步数据 同时释放sample_byte (*env)->ReleaseByteArrayElements(env,audio_sample_array,sample_byte,0); //AudioTrack.write PCM数据 (*env)->CallIntMethod(env,audio_track,audio_track_write_mid,audio_sample_array,0,out_buffer_size); //释放局部引用 否则报错JNI ERROR (app bug): local reference table overflow (max=512) (*env)->DeleteLocalRef(env,audio_sample_array); usleep(1000 * 16); //16ms } } av_free_packet(packet); } av_frame_free(&frame); av_free(out_buffer); swr_free(&swrCtx); avcodec_close(pCodeCtx); avformat_close_input(&pFormatCtx); (*env)->ReleaseStringUTFChars(env, input_jstr, input_cstr);} 5.调用音频播放功能
/** * 音频解码 */ public void audioPlayer(){ /** * 1.播放视频文件中的音频 */ // String input = new File(Environment.getExternalStorageDirectory(),"告白气球.avi").getAbsolutePath(); /** * 2.播放音频文件中的音频 */ String input = new File(Environment.getExternalStorageDirectory(),"说散就散.mp3").getAbsolutePath(); VideoPlayer player = new VideoPlayer(); player.audioPlayer(input); Log.d("Main","正在播放"); }}6.调用音频播放功能
Log输出
I/ffmpegandroidplayer: initI/ffmpegandroidplayer: out_count:2I/AudioUtil: nb_channels:2I/AudioUtil: sampleRateInHz:44100I/ffmpegandroidplayer: 解码：0I/ffmpegandroidplayer: 解码：1I/ffmpegandroidplayer: 解码：2I/ffmpegandroidplayer: 解码：3I/ffmpegandroidplayer: 解码：4太多省略......至此，音频播放功能已完成。
源码下载
Github：https://github.com/kpioneer123/FFmpegTest
特别感谢：
动脑学院Jason
微信号kpioneer
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