android采用FFmpeg实现音频混合与拼接剪切

defaultConfig {
 ......
 externalNativeBuild {
  cmake {
  cppFlags ""
  }
 }
 ndk {
  abiFilters "armeabi-v7a"
 }
 }

externalNativeBuild {
 cmake {
  path "CMakeLists.txt"
 }
 }
 sourceSets {
 main {
  jniLibs.srcDirs = ['libs']
  jni.srcDirs = []
 }
 }

add_library( # Sets the name of the library.
  audio-handle
 
  # Sets the library as a shared library.
  SHARED
 
  # Provides a relative path to your source file(s).
  src/main/cpp/ffmpeg_cmd.c
  src/main/cpp/cmdutils.c
  src/main/cpp/ffmpeg.c
  src/main/cpp/ffmpeg_filter.c
  src/main/cpp/ffmpeg_opt.c)
add_library( ffmpeg
  SHARED
  IMPORTED )
set_target_properties( ffmpeg
   PROPERTIES IMPORTED_LOCATION
   ../../../../libs/armeabi-v7a/libffmpeg.so )
include_directories(src/main/cpp/include)
find_library( log-lib
  log )
target_link_libraries( audio-handle
   ffmpeg
   ${log-lib} )
调用FFmpeg命令行进行音频处理：
 /**
 * 调用ffmpeg处理音频
 * @param handleType handleType
 */
 private void doHandleAudio(int handleType){
 String[] commandLine = null;
 switch (handleType){
  case 0://转码
  String transformFile = PATH + File.separator + "transform.aac";
  commandLine = FFmpegUtil.transformAudio(srcFile, transformFile);
  break;
  case 1://剪切
  String cutFile = PATH + File.separator + "cut.mp3";
  commandLine = FFmpegUtil.cutAudio(srcFile, 10, 15, cutFile);
  break;
  case 2://合并
  String concatFile = PATH + File.separator + "concat.mp3";
  commandLine = FFmpegUtil.concatAudio(srcFile, appendFile, concatFile);
  break;
  case 3://混合
  String mixFile = PATH + File.separator + "mix.aac";
  commandLine = FFmpegUtil.mixAudio(srcFile, appendFile, mixFile);
  break;
  default:
  break;
 }
 executeFFmpegCmd(commandLine);
 }

/**
 * 使用ffmpeg命令行进行音频转码
 * @param srcFile 源文件
 * @param targetFile 目标文件（后缀指定转码格式）
 * @return 转码后的文件
 */
 public static String[] transformAudio(String srcFile, String targetFile){
 String transformAudioCmd = "ffmpeg -i %s %s";
 transformAudioCmd = String.format(transformAudioCmd, srcFile, targetFile);
 return transformAudioCmd.split(" ");//以空格分割为字符串数组
 }
 
 /**
 * 使用ffmpeg命令行进行音频剪切
 * @param srcFile 源文件
 * @param startTime 剪切的开始时间(单位为秒)
 * @param duration 剪切时长(单位为秒)
 * @param targetFile 目标文件
 * @return 剪切后的文件
 */
 @SuppressLint("DefaultLocale")
 public static String[] cutAudio(String srcFile, int startTime, int duration, String targetFile){
 String cutAudioCmd = "ffmpeg -i %s -ss %d -t %d %s";
 cutAudioCmd = String.format(cutAudioCmd, srcFile, startTime, duration, targetFile);
 return cutAudioCmd.split(" ");//以空格分割为字符串数组
 }
 
 /**
 * 使用ffmpeg命令行进行音频合并
 * @param srcFile 源文件
 * @param appendFile 待追加的文件
 * @param targetFile 目标文件
 * @return 合并后的文件
 */
 public static String[] concatAudio(String srcFile, String appendFile, String targetFile){
 String concatAudioCmd = "ffmpeg -i concat:%s|%s -acodec copy %s";
 concatAudioCmd = String.format(concatAudioCmd, srcFile, appendFile, targetFile);
 return concatAudioCmd.split(" ");//以空格分割为字符串数组
 }
 
 /**
 * 使用ffmpeg命令行进行音频混合
 * @param srcFile 源文件
 * @param mixFile 待混合文件
 * @param targetFile 目标文件
 * @return 混合后的文件
 */
 public static String[] mixAudio(String srcFile, String mixFile, String targetFile){
 String mixAudioCmd = "ffmpeg -i %s -i %s -filter_complex amix=inputs=2:duration=first -strict -2 %s";
 mixAudioCmd = String.format(mixAudioCmd, srcFile, mixFile, targetFile);
 return mixAudioCmd.split(" ");//以空格分割为字符串数组
 }

public static void execute(final String[] commands, final OnHandleListener onHandleListener){
 new Thread(new Runnable() {
  @Override
  public void run() {
  if(onHandleListener != null){
   onHandleListener.onBegin();
  }
  //调用ffmpeg进行处理
  int result = handle(commands);
  if(onHandleListener != null){
   onHandleListener.onEnd(result);
  }
  }
 }).start();
 }
 private native static int handle(String[] commands);

JNIEXPORT jint JNICALL Java_com_frank_ffmpeg_FFmpegCmd_handle
(JNIEnv *env, jclass obj, jobjectArray commands){
 int argc = (*env)->GetArrayLength(env, commands);
 char **argv = (char**)malloc(argc * sizeof(char*));
 int i;
 int result;
 for (i = 0; i < argc; i++) {
 jstring jstr = (jstring) (*env)->GetObjectArrayElement(env, commands, i);
 char* temp = (char*) (*env)->GetStringUTFChars(env, jstr, 0);
 argv[i] = malloc(1024);
 strcpy(argv[i], temp);
 (*env)->ReleaseStringUTFChars(env, jstr, temp);
 }
 //执行ffmpeg命令
 result = run(argc, argv);
 //释放内存
 for (i = 0; i < argc; i++) {
 free(argv[i]);
 }
 free(argv);
 return result;
}

int run(int argc, char **argv)
{
 /****************省略********************/
 //注册各个模块
 avcodec_register_all();
#if CONFIG_AVDEVICE
 avdevice_register_all();
#endif
 avfilter_register_all();
 av_register_all();
 avformat_network_init();
 show_banner(argc, argv, options);
 term_init();
 /****************省略********************/
 //解析命令选项与打开输入输出文件
 int ret = ffmpeg_parse_options(argc, argv);
 if (ret < 0)
 exit_program(1);
 /****************省略********************/
 //文件转换
 if (transcode() < 0)
 exit_program(1);
 /****************省略********************/
 //退出程序操作：关闭文件、释放内存
 exit_program(received_nb_signals ? 255 : main_return_code);
 ffmpeg_cleanup(0);
}

static int transcode(void)
{
 int ret, i;
 AVFormatContext *os;
 OutputStream *ost;
 InputStream *ist;
 int64_t timer_start;
 int64_t total_packets_written = 0;
 //转码方法初始化
 ret = transcode_init();
 if (ret < 0)
 goto fail;
 
 if (stdin_interaction) {
 av_log(NULL, AV_LOG_INFO, "Press [q] to stop, [?] for help\n");
 }
 timer_start = av_gettime_relative();
 
#if HAVE_PTHREADS
 if ((ret = init_input_threads()) < 0)
 goto fail;
#endif
 //transcode循环处理
 while (!received_sigterm) {
 int64_t cur_time= av_gettime_relative();
 
 //如果遇到"q"命令，则退出循环
 if (stdin_interaction)
  if (check_keyboard_interaction(cur_time) < 0)
  break;
 
 //判断是否还有输出流
 if (!need_output()) {
  av_log(NULL, AV_LOG_VERBOSE, "No more output streams to write to, finishing.\n");
  break;
 }
 
 ret = transcode_step();
 if (ret < 0 && ret != AVERROR_EOF) {
  char errbuf[128];
  av_strerror(ret, errbuf, sizeof(errbuf));
 
  av_log(NULL, AV_LOG_ERROR, "Error while filtering: %s\n", errbuf);
  break;
 }
 
 //打印音视频流信息
 print_report(0, timer_start, cur_time);
 }
#if HAVE_PTHREADS
 free_input_threads();
#endif
 
 //文件末尾最后一个stream，刷新解码器buffer
 for (i = 0; i < nb_input_streams; i++) {
 ist = input_streams[i];
 if (!input_files[ist->file_index]->eof_reached && ist->decoding_needed) {
  process_input_packet(ist, NULL, 0);
 }
 }
 flush_encoders();
 term_exit();
 
 //写文件尾，关闭文件
 for (i = 0; i < nb_output_files; i++) {
 os = output_files[i]->ctx;
 if ((ret = av_write_trailer(os)) < 0) {
  av_log(NULL, AV_LOG_ERROR, "Error writing trailer of %s: %s", os->filename, av_err2str(ret));
  if (exit_on_error)
  exit_program(1);
 }
 }
 
 //关闭所有编码器
 for (i = 0; i < nb_output_streams; i++) {
 ost = output_streams[i];
 if (ost->encoding_needed) {
  av_freep(&ost->enc_ctx->stats_in);
 }
 total_packets_written += ost->packets_written;
 }
 
 if (!total_packets_written && (abort_on_flags & ABORT_ON_FLAG_EMPTY_OUTPUT)) {
 av_log(NULL, AV_LOG_FATAL, "Empty output\n");
 exit_program(1);
 }
 
 //关闭所有解码器
 for (i = 0; i < nb_input_streams; i++) {
 ist = input_streams[i];
 if (ist->decoding_needed) {
  avcodec_close(ist->dec_ctx);
  if (ist->hwaccel_uninit)
  ist->hwaccel_uninit(ist->dec_ctx);
 }
 }
 
 //省略最后的释放内存
 return ret;
}