Android ffmpeg 音频的解码和播放
FFmpeg在音视频开发的地位不必多说,它已经是行业的一个品牌标杆。本篇文章探讨使用FFmpeg进行音频解码,然后反射调用android系统自带的AudioTrack和OpenSL ES两种播放方式。
首先谈下FFmpeg解码流程,步骤包括:注册组件、分配FormatContext、打开音频文件、获取输入文件信息、获取音频流索引位置、获取音频解码器、打开解码器、循环读取待解码数据、解码完一帧送去播放器播放。
代码如下:
# For more information about using CMake with Android Studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html
# Sets the minimum version of CMake required to build the native library.
cmake_minimum_required(VERSION 3.4.1)
add_definitions(-std=c++11)
find_library( # Sets the name of the path variable.
log-lib
# Specifies the name of the NDK library that
# you want CMake to locate.
log )
find_library( # Sets the name of the path variable.
android-lib
# Specifies the name of the NDK library that
# you want CMake to locate.
android )
set(distribution_DIR ${CMAKE_SOURCE_DIR}/libs/armeabi)
add_library( avutil
SHARED
IMPORTED )
set_target_properties( avutil
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/libavutil-54.so )
add_library( swresample
SHARED
IMPORTED )
set_target_properties( swresample
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/libswresample-1.so)
add_library( avcodec
SHARED
IMPORTED )
set_target_properties( avcodec
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/libavcodec-56.so)
add_library( avformat
SHARED
IMPORTED )
set_target_properties( avformat
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/libavformat-56.so)
add_library( swscale
SHARED
IMPORTED )
set_target_properties( swscale
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/libswscale-3.so)
add_library( postproc
SHARED
IMPORTED )
set_target_properties( postproc
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/libpostproc-53.so)
add_library( avfilter
SHARED
IMPORTED )
set_target_properties( avfilter
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/libavfilter-5.so)
add_library( avdevice
SHARED
IMPORTED )
set_target_properties( avdevice
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/libavdevice-56.so)
add_library(yuv
SHARED
IMPORTED)
set_target_properties(yuv
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/libyuv.so)
add_library(
myffmpeg
SHARED
src/main/cpp/ffmpeg.cpp
src/main/cpp/SongPlayer.cpp
)
include_directories(src/main/cpp/include)
target_link_libraries(# Specifies the target library.
myffmpeg
avutil
swresample
avcodec
avformat
swscale
postproc
avfilter
avdevice
yuv
${android-lib}
${log-lib}
)
java层代码
/**
* 视频播放的控制器
* @author Jason
* QQ: 1476949583
* @date 2016年9月19日
* @version 1.0
*/
public class JasonPlayer {
public native void render(String input,Surface surface);
public native void sound(String input,String output);
/**
* 创建一个AudioTrac对象,用于播放
* @param nb_channels
* @return
*/
public AudioTrack createAudioTrack(int sampleRateInHz, int nb_channels){
//固定格式的音频码流
int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
Log.i("jason", "nb_channels:"+nb_channels);
//声道布局
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);
//播放
//audioTrack.play();
//写入PCM
//audioTrack.write(audioData, offsetInBytes, sizeInBytes);
return audioTrack;
}
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");
}
}
JNI层代码
#include "com_dongnaoedu_dnffmpegplayer_JasonPlayer.h"
#include <stdlib.h>
#include <unistd.h>
#include <android/log.h>
#define LOGI(FORMAT,...) __android_log_print(ANDROID_LOG_INFO,"jason",FORMAT,##__VA_ARGS__);
#define LOGE(FORMAT,...) __android_log_print(ANDROID_LOG_ERROR,"jason",FORMAT,##__VA_ARGS__);
#define MAX_AUDIO_FRME_SIZE 48000 * 4
//封装格式
#include "libavformat/avformat.h"
//解码
#include "libavcodec/avcodec.h"
//缩放
#include "libswscale/swscale.h"
//重采样
#include "libswresample/swresample.h"
JNIEXPORT void JNICALL Java_com_dongnaoedu_dnffmpegplayer_JasonPlayer_sound
(JNIEnv *env, jobject jthiz, jstring input_jstr, jstring output_jstr){
const char* input_cstr = (*env)->GetStringUTFChars(env,input_jstr,NULL);
const char* output_cstr = (*env)->GetStringUTFChars(env,output_jstr,NULL);
LOGI("%s","sound");
//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;
}
}
//获取解码器
AVCodecContext *codecCtx = pFormatCtx->streams[audio_stream_idx]->codec;
AVCodec *codec = avcodec_find_decoder(codecCtx->codec_id);
if(codec == NULL){
LOGI("%s","无法获取解码器");
return;
}
//打开解码器
if(avcodec_open2(codecCtx,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();
//重采样设置参数-------------start
//输入的采样格式
enum AVSampleFormat in_sample_fmt = codecCtx->sample_fmt;
//输出采样格式16bit PCM
enum AVSampleFormat out_sample_fmt = AV_SAMPLE_FMT_S16;
//输入采样率
int in_sample_rate = codecCtx->sample_rate;
//输出采样率
int out_sample_rate = in_sample_rate;
//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stereo)
//av_get_default_channel_layout(codecCtx->channels);
uint64_t in_ch_layout = codecCtx->channel_layout;
//输出的声道布局(立体声)
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);
//输出的声道个数
int out_channel_nb = av_get_channel_layout_nb_channels(out_ch_layout);
//重采样设置参数-------------end
//JNI begin------------------
//JasonPlayer
jclass player_class = (*env)->GetObjectClass(env,jthiz);
//AudioTrack对象
jmethodID create_audio_track_mid = (*env)->GetMethodID(env,player_class,"createAudioTrack","(II)Landroid/media/AudioTrack;");
jobject audio_track = (*env)->CallObjectMethod(env,jthiz,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");
//JNI end------------------
FILE *fp_pcm = fopen(output_cstr,"wb");
//16bit 44100 PCM 数据
uint8_t *out_buffer = (uint8_t *)av_malloc(MAX_AUDIO_FRME_SIZE);
int got_frame = 0,index = 0, ret;
//不断读取压缩数据
while(av_read_frame(pFormatCtx,packet) >= 0){
//解码音频类型的Packet
if(packet->stream_index == audio_stream_idx){
//解码
ret = avcodec_decode_audio4(codecCtx,frame,&got_frame,packet);
if(ret < 0){
LOGI("%s","解码完成");
}
//解码一帧成功
if(got_frame > 0){
LOGI("解码:%d",index++);
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);
fwrite(out_buffer,1,out_buffer_size,fp_pcm);
//out_buffer缓冲区数据,转成byte数组
jbyteArray audio_sample_array = (*env)->NewByteArray(env,out_buffer_size);
jbyte* sample_bytep = (*env)->GetByteArrayElements(env,audio_sample_array,NULL);
//out_buffer的数据复制到sampe_bytep
memcpy(sample_bytep,out_buffer,out_buffer_size);
//同步
(*env)->ReleaseByteArrayElements(env,audio_sample_array,sample_bytep,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
(*env)->DeleteLocalRef(env,audio_sample_array);
usleep(1000 * 16);
}
}
av_free_packet(packet);
}
av_frame_free(&frame);
av_free(out_buffer);
swr_free(&swrCtx);
avcodec_close(codecCtx);
avformat_close_input(&pFormatCtx);
(*env)->ReleaseStringUTFChars(env,input_jstr,input_cstr);
(*env)->ReleaseStringUTFChars(env,output_jstr,output_cstr);
}