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本教程会教大家集成FFmpeg，并使用FFmpeg的代码（非命令行）进行播放mp3。 目录 一、下载FFmpeg源码，编译出静态库.a/动态库.so 传送门：https://blog.csdn.net/gxhea/article/details/115539124 二、将库复制到项目中我编译的是.a静态库，复制到项目中；还需要复制FFmpeg的源代码到项目中，源代码在FFmpeg的根目录，具体复制哪些请看项目结构图片
NativeTools.java package com.example.ndk; public class NativeTools { static { System.loadLibrary("my_code");//这里的名字与cmake文件里面的my_code一致 } public static native String getWords(); public static native String getFfmpegVersion(); public static native void playMp3(MyPlay myPlay); } 六、创建cpp，编辑器会自动生成JNI方法native_test.cpp，需要注意的是：引用ffmpeg的代码必须要extern "C"{}包起来 // // Created by hins on 4/9/21. // #include <jni.h> #include <stdio.h> #include <stdlib.h> #include "android/log.h" #include <string> #include "include/hf_tools.h" extern "C" { #include "ffmpeg/include/libavcodec/avcodec.h" #include "ffmpeg/include/libavformat/avformat.h" #include "ffmpeg/include/libavfilter/avfilter.h" #include "ffmpeg/include/libavutil/file.h" #include "ffmpeg/include/libavutil/mathematics.h" #include "ffmpeg/include/libavutil/time.h" #include "ffmpeg/include/libavutil/mem.h" #include "ffmpeg/include/libswresample/swresample.h" //extern "C" JNIEXPORT jstring JNICALL Java_com_example_ndk_NativeTools_getWords(JNIEnv *env, jclass clazz) { std::string hello = "Hello from C++"; return env->NewStringUTF(hello.c_str()); } JNIEXPORT jstring JNICALL Java_com_example_ndk_NativeTools_getFfmpegVersion(JNIEnv *env, jclass clazz) { char strBuffer[1024 * 4] = {0}; strcat(strBuffer, "libavcodec : "); strcat(strBuffer, AV_STRINGIFY(LIBAVCODEC_VERSION)); strcat(strBuffer, "\nlibavformat : "); strcat(strBuffer, AV_STRINGIFY(LIBAVFORMAT_VERSION)); strcat(strBuffer, "\nlibavutil : "); strcat(strBuffer, AV_STRINGIFY(LIBAVUTIL_VERSION)); strcat(strBuffer, "\nlibavfilter : "); strcat(strBuffer, AV_STRINGIFY(LIBAVFILTER_VERSION)); strcat(strBuffer, "\nlibswresample : "); strcat(strBuffer, AV_STRINGIFY(LIBSWRESAMPLE_VERSION)); strcat(strBuffer, "\nlibswscale : "); strcat(strBuffer, AV_STRINGIFY(LIBSWSCALE_VERSION)); strcat(strBuffer, "\navcodec_configure : \n"); strcat(strBuffer, avcodec_configuration()); strcat(strBuffer, "\navcodec_license : "); strcat(strBuffer, avcodec_license()); return env->NewStringUTF(strBuffer); } JNIEXPORT void JNICALL Java_com_example_ndk_NativeTools_playMp3(JNIEnv *env, jclass clazz, jobject my_play) { //1.注册组件，打开音频文件并获取内容，找到音频流 av_register_all(); avformat_network_init(); AVFormatContext *avFormatContext = avformat_alloc_context();//获取上下文 const char *url = "/data/user/0/com.example.ndk/app_mp3/aaa.mp3"; HTools::logd("url is " + string(url)); int ret = avformat_open_input(&avFormatContext, url, NULL, NULL); if (ret != 0) { HTools::logd("Couldn't open input stream. " + string(av_err2str(ret))); return; } else { HTools::logd("open input stream. file: " + string(url)); } //获取码流信息 avformat_find_stream_info(avFormatContext, NULL); int audio_stream_idx = -1; for (int i = 0; i < avFormatContext->nb_streams; ++i) { if (avFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO) { //如果是视频流,标记一哈 audio_stream_idx = i; HTools::logd("找到了音频流"); } } //2.获取解码器，申请avframe和avpacket： //获取解码器上下文 AVCodecContext *pCodecCtx = avFormatContext->streams[audio_stream_idx]->codec; //获取解码器 AVCodec *pCodex = avcodec_find_decoder(pCodecCtx->codec_id); //打开解码器 if (avcodec_open2(pCodecCtx, pCodex, NULL) < 0) { } //申请avpakcet，装解码前的数据 AVPacket *packet = (AVPacket *) av_malloc(sizeof(AVPacket)); //申请avframe，装解码后的数据 AVFrame *frame = av_frame_alloc(); HTools::logd("2.获取解码器成功"); //3.初始化SwrContext，进行重采样 //得到SwrContext ，进行重采样，具体参考 SwrContext *swrContext = swr_alloc(); //缓存区 uint8_t *out_buffer = (uint8_t *) av_malloc(44100 * 2); //输出的声道布局（立体声） uint64_t out_ch_layout = AV_CH_LAYOUT_STEREO; //输出采样位数 16位 enum AVSampleFormat out_formart = AV_SAMPLE_FMT_S16; //输出的采样率必须与输入相同 int out_sample_rate = pCodecCtx->sample_rate; //swr_alloc_set_opts将PCM源文件的采样格式转换为自己希望的采样格式 swr_alloc_set_opts(swrContext, out_ch_layout, out_formart, out_sample_rate, pCodecCtx->channel_layout, pCodecCtx->sample_fmt, pCodecCtx->sample_rate, 0, NULL); swr_init(swrContext); HTools::logd("3.初始化SwrContext，进行重采样成功"); //4.通过while循环读取内容，并通过AudioTrack进行播放： // 获取通道数 2 ，有单声道，双声道 int out_channel_nb = av_get_channel_layout_nb_channels(AV_CH_LAYOUT_STEREO); // 反射得到Class类型 jclass david_player = env->GetObjectClass(my_play); // 反射得到createAudio方法 jmethodID createAudio = env->GetMethodID(david_player, "createTrack", "(II)V"); // 反射调用createAudio //设置采样率为44100，目前为常用的采样率 env->CallVoidMethod(my_play, createAudio, 44100, out_channel_nb); jmethodID audio_write = env->GetMethodID(david_player, "playTrack", "([BI)V"); HTools::logd("调用android AudioTrack 开始播放mp3..."); int got_frame; while (av_read_frame(avFormatContext, packet) >= 0) { if (packet->stream_index == audio_stream_idx) { // 解码 mp3 编码格式frame----pcm frame avcodec_decode_audio4(pCodecCtx, frame, &got_frame, packet); if (got_frame) { HTools::logd("解码，读stream"); swr_convert(swrContext, &out_buffer, 44100 * 2, (const uint8_t **) frame->data, frame->nb_samples); // 缓冲区的大小 int size = av_samples_get_buffer_size(NULL, out_channel_nb, frame->nb_samples, AV_SAMPLE_FMT_S16, 1); jbyteArray audio_sample_array = env->NewByteArray(size); env->SetByteArrayRegion(audio_sample_array, 0, size, (const jbyte *) out_buffer); env->CallVoidMethod(my_play, audio_write, audio_sample_array, size); env->DeleteLocalRef(audio_sample_array); } } } HTools::logd("5.释放需要释放的资源"); //5.释放需要释放的资源 av_frame_free(&frame); swr_free(&swrContext); avcodec_close(pCodecCtx); avformat_close_input(&avFormatContext); return; } } 七、执行代码调用整体调用流程是：Java(playMp3) -> JNI -> ffmpeg -> Java(AudioTrack)播放 创建一个于ffmpeg交互的播放器类：MyPlay.java package com.example.ndk; import android.media.AudioFormat; import android.media.AudioManager; import android.media.AudioTrack; public class MyPlay { private AudioTrack audioTrack; // 这个方法 是C进行调用 public void createTrack(int sampleRateInHz, int nb_channals) { int channelConfig;//通道数 if (nb_channals == 1) { channelConfig = AudioFormat.CHANNEL_OUT_MONO; } else if (nb_channals == 2) { channelConfig = AudioFormat.CHANNEL_OUT_STEREO; } else { channelConfig = AudioFormat.CHANNEL_OUT_MONO; } int buffersize = AudioTrack.getMinBufferSize(sampleRateInHz, channelConfig, AudioFormat.ENCODING_PCM_16BIT); audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRateInHz, channelConfig, AudioFormat.ENCODING_PCM_16BIT, buffersize, AudioTrack.MODE_STREAM); audioTrack.play(); } //C传入音频数据 public void playTrack(byte[] buffer, int lenth) { if (audioTrack != null && audioTrack.getPlayState() == AudioTrack.PLAYSTATE_PLAYING) { audioTrack.write(buffer, 0, lenth); } } }在MainActivity里调用 package com.example.ndk import android.Manifest import android.os.Bundle import android.util.Log import androidx.appcompat.app.AppCompatActivity import androidx.core.app.ActivityCompat import java.io.File class MainActivity : AppCompatActivity() { // 要申请的权限 private val permissions = arrayOf<String>( Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.CAMERA ) override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) Log.d(ConsData.TAG, "native ：" + NativeTools.getWords()) ///data/user/0/com.example.ndk val dir: File = getDir(ConsData.DIR_MP3, MODE_PRIVATE) val p = dir.absolutePath val fileMp3 = File("$p/aaa.mp3") if(!fileMp3.exists()) { FileUtils.copyAssetsFiles2Dir(this, "aaa.mp3") } var myPlay = MyPlay() var t = Thread(object : Runnable { override fun run() { Log.d(ConsData.TAG, "ffmpeg do run...") NativeTools.playMp3(myPlay) } }); t.start() ActivityCompat.requestPermissions(this, permissions, 321); } }最后你会，听 海哭的声音 (责任编辑：) |
