聊天平台源码，聊天平台如何获取到音频流

聊天平台源码，聊天平台如何获取到音频流的相关代码

我们重采样的参数要和SDL的参数是一致的，还要考虑到虽然没有AVPacket了，但是解码器中还有未解码的数据，我们要用avcodec_send_packet(aCodecCtx, NULL)告诉解码器没有数据了，刷新解码器。

 

下面这段代码的逻辑是如果没有数据要解码了，就跳转到获取解码数据的逻辑。

 

1

int audio_decode_frame(AVCodecContext *aCodecCtx, uint8_t *audio_buf, int buf_size)<br>{<br> <br>  static AVPacket pkt;<br>  static uint8_t *audio_pkt_data = NULL;<br>  static int audio_pkt_size = 0;<br>  static AVFrame frame;<br>  av_frame_get_buffer(&frame, 0);<br>  int len1, data_size = 0;<br>  int ret = 0;<br>  int is_no_pkt = 0;<br> <br>  for (;;)<br>  {<br> <br>    if (pkt.data)<br>      av_packet_unref(&pkt);<br> <br>    if (quit)<br>    {<br>      return -1;<br>    }<br> <br>    if (packet_queue_get(&audioq, &pkt, 1) < 0)<br>    {<br>      ret = avcodec_send_packet(aCodecCtx, NULL);<br>      if (ret < 0)<br>      {<br>        return -1;<br>      }<br>      is_no_pkt = 1;<br>      goto __RECEIVE;<br>    }<br> <br>    ret = avcodec_send_packet(aCodecCtx, &pkt);<br>    if (ret < 0)<br>    {<br>      ret = -1;<br>      printf("decode error");<br>      av_packet_unref(&pkt);<br>      return -1;<br>    }<br>  __RECEIVE:<br>    if (is_no_pkt)<br>    {<br>      return -1;<br>    }<br>    else if (pkt.data)<br>    {<br>      av_packet_unref(&pkt);<br>    }<br>    ret = avcodec_receive_frame(aCodecCtx, &frame);<br>    if (ret < 0)<br>    {<br>      continue;<br>    }<br>    <br>    data_size = av_get_bytes_per_sample(out_format) * out_channel * SDL_AUDIO_BUFFER_SIZE;<br> <br>    swr_convert(audio_convert_ctx,<br>                &audio_buf,<br>                SDL_AUDIO_BUFFER_SIZE,<br>                (const uint8_t **)frame.data,<br>                frame.nb_samples);<br>    return data_size;<br>  }<br>}

​

转码后的数据大小=采样大小 * 单通道采样个数 * 通道数

data_size = av_get_bytes_per_sample(out_format) * out_channel * SDL_AUDIO_BUFFER_SIZE;

下面是完整的代码

 

1

#include <stdio.h><br>#include <assert.h><br> <br>#include <SDL2/SDL.h><br> <br>#include <libavcodec/avcodec.h><br>#include <libavformat/avformat.h><br>#include <libswscale/swscale.h><br>#include <libswresample/swresample.h><br>#include <libavutil/samplefmt.h><br> <br>#define SDL_AUDIO_BUFFER_SIZE 1024<br>#define MAX_AUDIO_FRAME_SIZE 192000<br>typedef struct PacketQueue<br>{<br>  AVPacketList *first_pkt, *last_pkt;<br>  int nb_packets;<br>  int size;<br>  SDL_mutex *mutex;<br>  SDL_cond *cond;<br>} PacketQueue;<br> <br>PacketQueue audioq;<br>int quit = 0;<br>struct SwrContext *audio_convert_ctx = NULL;<br>static Uint8 out_channel = 2;<br>static SDL_AudioFormat out_format = AV_SAMPLE_FMT_S16;<br>static int out_nb_samples = 0;<br>static int sample_rate = 48000;<br> <br> <br>void audio_callback(void *userdata, Uint8 *stream, int len);<br>void packet_queue_init(PacketQueue *q);<br>int packet_queue_put(PacketQueue *q, AVPacket *pkt);<br>int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block);<br>int audio_decode_frame(AVCodecContext *aCodecCtx, uint8_t *audio_buf, int buf_size);<br> <br>int main(int argc, char *argv[])<br>{<br>  int ret = 0;<br>  AVFormatContext *fmt_ctx = NULL;<br>  char *in_file;<br>  int video_stream_index = -1;<br>  int audio_stream_index = -1;<br>  AVCodec *video_codec = NULL, *audio_codec = NULL;<br>  AVCodecParameters *audio_codecpar = NULL, *video_codecpar = NULL;<br>  AVCodecContext *audio_codec_ctx = NULL, *video_codec_ctx = NULL;<br>  SDL_AudioSpec wanted_spec, src_spec;<br>  int64_t in_channel_layout;<br>  int64_t out_channel_layout;<br>  AVPacket packet;<br>  SDL_Event event;<br>  av_log_set_level(AV_LOG_INFO);<br> <br>  if (argc < 2)<br>  {<br>    av_log(NULL, AV_LOG_ERROR, "need infile\n");<br>    return -1;<br>  }<br>  in_file = argv[1];<br>  //初始化SDL<br>  ret = SDL_Init(SDL_INIT_AUDIO | SDL_INIT_VIDEO | SDL_INIT_TIMER);<br>  if (ret != 0)<br>  {<br>    av_log(NULL, AV_LOG_ERROR, "sdl init error\n");<br>    return ret;<br>  }<br> <br>  //获取输入文件上下文<br>  ret = avformat_open_input(&fmt_ctx,<br>                            in_file,<br>                            NULL,<br>                            NULL);<br>  if (!fmt_ctx)<br>  {<br>    av_log(NULL, AV_LOG_ERROR, "open input file fail\n");<br>    goto __FAIL;<br>  }<br> <br>  //获取视频流索引和音频流索引<br>  ret = avformat_find_stream_info(fmt_ctx, NULL);<br>  if (ret < 0)<br>  {<br>    av_log(NULL, AV_LOG_ERROR, "find stream fail\n");<br>    goto __FAIL;<br>  }<br>  av_dump_format(fmt_ctx, 0, in_file, 0);<br>  video_stream_index = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &video_codec, -1);<br>  audio_stream_index = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, &audio_codec, -1);<br>  if (video_stream_index < 0 || audio_stream_index < 0)<br>  {<br>    av_log(NULL, AV_LOG_ERROR, "find audio or video  fail\n");<br>    goto __FAIL;<br>  }<br>  if (!audio_codec || !video_codec)<br>  {<br>    ret = -1;<br>    av_log(NULL, AV_LOG_ERROR, "find audio codec or video codec fail");<br>    goto __FAIL;<br>  }<br>  //获取解码器上下文并打开解码器<br>  audio_codecpar = fmt_ctx->streams[audio_stream_index]->codecpar;<br>  out_nb_samples = audio_codecpar->frame_size;<br> <br>  video_codecpar = fmt_ctx->streams[video_stream_index]->codecpar;<br> <br>  audio_codec_ctx = avcodec_alloc_context3(audio_codec);<br>  video_codec_ctx = avcodec_alloc_context3(video_codec);<br> <br>  avcodec_parameters_to_context(audio_codec_ctx, audio_codecpar);<br>  avcodec_parameters_to_context(video_codec_ctx, video_codecpar);<br> <br>  ret = avcodec_open2(audio_codec_ctx, audio_codec, NULL);<br>  if (ret < 0)<br>  {<br>    av_log(NULL, AV_LOG_ERROR, "open audio codec fail\n");<br>    goto __FAIL;<br>  }<br> <br>  ret = avcodec_open2(video_codec_ctx, video_codec, NULL);<br>  if (ret < 0)<br>  {<br>    av_log(NULL, AV_LOG_ERROR, "open video codec fail\n");<br>    goto __FAIL;<br>  }<br> <br>  //设置SDL_音频参数<br>  wanted_spec.freq = sample_rate;  //采样率<br>  wanted_spec.format = AUDIO_S16LSB; //采样大小<br>  wanted_spec.channels = out_channel; //声道数<br>  wanted_spec.silence = 0;<br>  wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;  //采样个数<br>  wanted_spec.callback = audio_callback;<br>  wanted_spec.userdata = audio_codec_ctx;<br> <br>  ret = SDL_OpenAudio(&wanted_spec, &src_spec);<br>  if (ret < 0)<br>  {<br>    av_log(NULL, AV_LOG_ERROR, "open audio device fail\n");<br>    goto __FAIL;<br>  }<br> <br>  //设置重采样<br>  in_channel_layout = audio_codecpar->channel_layout;<br>  out_channel_layout = av_get_default_channel_layout(out_channel);<br>  audio_convert_ctx = swr_alloc();<br>  if (!audio_convert_ctx)<br>  {<br>    ret = -1;<br>    av_log(NULL, AV_LOG_ERROR, "alloc  swr fail\n");<br>    goto __FAIL;<br>  }<br> <br>  swr_alloc_set_opts(audio_convert_ctx,<br>                     out_channel_layout,<br>                     out_format,<br>                     sample_rate,<br>                     in_channel_layout,<br>                     audio_codecpar->format,<br>                     audio_codecpar->sample_rate,<br>                     0,<br>                     NULL);<br> <br>  swr_init(audio_convert_ctx);<br>  SDL_PauseAudio(0);<br> <br>  packet_queue_init(&audioq);<br>  while (av_read_frame(fmt_ctx, &packet) >= 0)<br>  {<br>    if (packet.stream_index == audio_stream_index)<br>    {<br>      packet_queue_put(&audioq, &packet);<br>    }<br>    else<br>    {<br>      av_packet_unref(&packet);<br>    }<br>    SDL_PollEvent(&event);<br>    switch (event.type)<br>    {<br>    case SDL_QUIT:<br>      quit = 1;<br>      goto __FAIL;<br>      break;<br>    default:<br>      break;<br>    }<br>  }<br>  while (1)<br>  {<br>    SDL_WaitEvent(&event);<br>    switch (event.type)<br>    {<br>    case SDL_QUIT:<br>      quit = 1;<br>      goto __FAIL;<br>      break;<br>    default:<br>      break;<br>    }<br>  }<br> <br>__FAIL:<br>  SDL_CloseAudio();<br>  SDL_Quit();<br>  if (audio_codecpar)<br>  {<br>    avcodec_parameters_free(&audio_codecpar);<br>  }<br> <br>  if (video_codecpar)<br>  {<br>    avcodec_parameters_free(&video_codecpar);<br>  }<br> <br>  if (video_codec_ctx)<br>  {<br>    avcodec_close(video_codec_ctx);<br>    avcodec_free_context(&video_codec_ctx);<br>  }<br> <br>  if (audio_codec_ctx)<br>  {<br>    avcodec_close(audio_codec_ctx);<br>    avcodec_free_context(&audio_codec_ctx);<br>  }<br>  if (fmt_ctx)<br>  {<br>    avformat_close_input(&fmt_ctx);<br>    avformat_free_context(fmt_ctx);<br>  }<br> <br>  return ret;<br>}<br> <br>void audio_callback(void *userdata, Uint8 *stream, int len)<br>{<br> <br>  AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;<br>  int len1, audio_size;<br> <br>  static uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE * 3) / 2];<br>  static unsigned int audio_buf_size = 0;<br>  static unsigned int audio_buf_index = 0;<br> <br>  while (len > 0)<br>  {<br>    if (audio_buf_index >= audio_buf_size)<br>    {<br>      /* We have already sent all our data; get more */<br>      audio_size = audio_decode_frame(aCodecCtx, audio_buf, sizeof(audio_buf));<br>      if (audio_size < 0)<br>      {<br>        /* If error, output silence */<br>        audio_buf_size = 1024; // arbitrary?<br>        memset(audio_buf, 0, audio_buf_size);<br>      }<br>      else<br>      {<br>        audio_buf_size = audio_size;<br>      }<br>      audio_buf_index = 0;<br>    }<br>    len1 = audio_buf_size - audio_buf_index;<br>    if (len1 > len)<br>      len1 = len;<br>    fprintf(stderr, "index=%d, len1=%d, len=%d\n",<br>            audio_buf_index,<br>            len,<br>            len1);<br>    memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);<br>    len -= len1;<br>    stream += len1;<br>    audio_buf_index += len1;<br>  }<br>}<br> <br>void packet_queue_init(PacketQueue *q)<br>{<br>  memset(q, 0, sizeof(PacketQueue));<br>  q->mutex = SDL_CreateMutex();<br>  q->cond = SDL_CreateCond();<br>}<br> <br>int packet_queue_put(PacketQueue *q, AVPacket *pkt)<br>{<br> <br>  AVPacketList *pkt1;<br>  AVPacket dst_pkt;<br>  av_init_packet(&dst_pkt);<br>  if (av_packet_ref(&dst_pkt, pkt) < 0)<br>  {<br>    return -1;<br>  }<br>  pkt1 = av_malloc(sizeof(AVPacketList));<br>  if (!pkt1)<br>    return -1;<br>  pkt1->pkt = dst_pkt;<br>  pkt1->next = NULL;<br> <br>  SDL_LockMutex(q->mutex);<br> <br>  if (!q->last_pkt)<br>  {<br>    q->first_pkt = pkt1;<br>  }<br>  else<br>  {<br>    q->last_pkt->next = pkt1;<br>  }<br> <br>  q->last_pkt = pkt1;<br>  q->nb_packets++;<br>  q->size += pkt1->pkt.size;<br>  SDL_CondSignal(q->cond);<br> <br>  SDL_UnlockMutex(q->mutex);<br>  return 0;<br>}<br> <br>int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block)<br>{<br>  AVPacketList *pkt1;<br>  int ret;<br> <br>  SDL_LockMutex(q->mutex);<br> <br>  for (;;)<br>  {<br> <br>    if (quit)<br>    {<br>      ret = -1;<br>      break;<br>    }<br> <br>    pkt1 = q->first_pkt;<br>    if (pkt1)<br>    {<br>      q->first_pkt = pkt1->next;<br>      if (!q->first_pkt)<br>        q->last_pkt = NULL;<br>      q->nb_packets--;<br>      q->size -= pkt1->pkt.size;<br>      *pkt = pkt1->pkt;<br>      av_free(pkt1);<br>      ret = 1;<br>      break;<br>    }<br>    else if (!block)<br>    {<br>      ret = 0;<br>      break;<br>    }<br>    else<br>    {<br>      SDL_CondWait(q->cond, q->mutex);<br>    }<br>  }<br>  SDL_UnlockMutex(q->mutex);<br>  return ret;<br>}<br> <br>int audio_decode_frame(AVCodecContext *aCodecCtx, uint8_t *audio_buf, int buf_size)<br>{<br> <br>  static AVPacket pkt;<br>  static uint8_t *audio_pkt_data = NULL;<br>  static int audio_pkt_size = 0;<br>  static AVFrame frame;<br>  av_frame_get_buffer(&frame, 0);<br>  int len1, data_size = 0;<br>  int ret = 0;<br>  int is_no_pkt = 0;<br> <br>  for (;;)<br>  {<br> <br>    if (pkt.data)<br>      av_packet_unref(&pkt);<br> <br>    if (quit)<br>    {<br>      return -1;<br>    }<br> <br>    if (packet_queue_get(&audioq, &pkt, 1) < 0)<br>    {<br>      ret = avcodec_send_packet(aCodecCtx, NULL);<br>      if (ret < 0)<br>      {<br>        return -1;<br>      }<br>      is_no_pkt = 1;<br>      goto __RECEIVE;<br>    }<br> <br>    ret = avcodec_send_packet(aCodecCtx, &pkt);<br>    if (ret < 0)<br>    {<br>      ret = -1;<br>      printf("decode error");<br>      av_packet_unref(&pkt);<br>      return -1;<br>    }<br>  __RECEIVE:<br>    if (is_no_pkt)<br>    {<br>      return -1;<br>    }<br>    else if (pkt.data)<br>    {<br>      av_packet_unref(&pkt);<br>    }<br>    ret = avcodec_receive_frame(aCodecCtx, &frame);<br>    if (ret < 0)<br>    {<br>      continue;<br>    }<br>    <br>    data_size = av_get_bytes_per_sample(out_format) * out_channel * SDL_AUDIO_BUFFER_SIZE;<br> <br>    swr_convert(audio_convert_ctx,<br>                &audio_buf,<br>                SDL_AUDIO_BUFFER_SIZE,<br>                (const uint8_t **)frame.data,<br>                frame.nb_samples);<br>    return data_size;<br>  }<br>}

 

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