实战--实现任意格式文件的音视频播放器

#include <stdio.h>
#include <assert.h>
#include <SDL.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libswresample/swresample.h>
// compatibility with newer API
#if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(55,28,1)
#define av_frame_alloc avcodec_alloc_frame
#define av_frame_free avcodec_free_frame
#endif
#define SDL_AUDIO_BUFFER_SIZE 1024
#define MAX_AUDIO_FRAME_SIZE 192000
struct SwrContext *audio_convert_ctx = NULL;
typedef struct PacketQueue {
  AVPacketList *first_pkt, *last_pkt;
  int nb_packets;
  int size;
  SDL_mutex *mutex;
  SDL_cond *cond;
} PacketQueue;
PacketQueue audioq;
int quit = 0;
void packet_queue_init(PacketQueue *q) {
  memset(q, 0, sizeof(PacketQueue));
  q->mutex = SDL_CreateMutex();
  q->cond = SDL_CreateCond();
}
int packet_queue_put(PacketQueue *q, AVPacket *pkt) {
  AVPacketList *pkt1;
  if(av_dup_packet(pkt) < 0) {
    return -1;
  }
  pkt1 = av_malloc(sizeof(AVPacketList));
  if (!pkt1)
    return -1;
  pkt1->pkt = *pkt;
  pkt1->next = NULL;
  SDL_LockMutex(q->mutex);
  if (!q->last_pkt) {
    q->first_pkt = pkt1;
  }else{
    q->last_pkt->next = pkt1;
  }
  q->last_pkt = pkt1;
  q->nb_packets++;
  q->size += pkt1->pkt.size;
  SDL_CondSignal(q->cond);
  SDL_UnlockMutex(q->mutex);
  return 0;
}
int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block)
{
  AVPacketList *pkt1;
  int ret;
  SDL_LockMutex(q->mutex);
  for(;;) {
    if(quit) {
      ret = -1;
      break;
    }
    pkt1 = q->first_pkt;
    if (pkt1) {
      q->first_pkt = pkt1->next;
      if (!q->first_pkt)
  q->last_pkt = NULL;
      q->nb_packets--;
      q->size -= pkt1->pkt.size;
      *pkt = pkt1->pkt;
      av_free(pkt1);
      ret = 1;
      break;
    } else if (!block) {
      ret = 0;
      break;
    } else {
      SDL_CondWait(q->cond, q->mutex);
    }
  }
  SDL_UnlockMutex(q->mutex);
  return ret;
}
int audio_decode_frame(AVCodecContext *aCodecCtx, uint8_t *audio_buf, int buf_size) {
  static AVPacket pkt;
  static uint8_t *audio_pkt_data = NULL;
  static int audio_pkt_size = 0;
  static AVFrame frame;
  int len1, data_size = 0;
  for(;;) {
    while(audio_pkt_size > 0) {
      int got_frame = 0;
      len1 = avcodec_decode_audio4(aCodecCtx, &frame, &got_frame, &pkt);
      if(len1 < 0) {
  /* if error, skip frame */
  audio_pkt_size = 0;
  break;
      }
      audio_pkt_data += len1;
      audio_pkt_size -= len1;
      data_size = 0;
      if(got_frame) {
        //fprintf(stderr, "channels:%d, nb_samples:%d, sample_fmt:%d \n", aCodecCtx->channels, frame.nb_samples, aCodecCtx->sample_fmt);
        /*
  data_size = av_samples_get_buffer_size(NULL, 
                 aCodecCtx->channels,
                 frame.nb_samples,
                 aCodecCtx->sample_fmt,
                 1);
        */
  data_size = 2 * 2 * frame.nb_samples;
  assert(data_size <= buf_size);
  swr_convert(audio_convert_ctx,
        &audio_buf,
        MAX_AUDIO_FRAME_SIZE*3/2,
        (const uint8_t **)frame.data,
        frame.nb_samples);
  //memcpy(audio_buf, frame.data[0], data_size);
      }
      if(data_size <= 0) {
  /* No data yet, get more frames */
  continue;
      }
      /* We have data, return it and come back for more later */
      return data_size;
    }
    if(pkt.data)
      av_free_packet(&pkt);
    if(quit) {
      return -1;
    }
    if(packet_queue_get(&audioq, &pkt, 1) < 0) {
      return -1;
    }
    audio_pkt_data = pkt.data;
    audio_pkt_size = pkt.size;
  }
}
void audio_callback(void *userdata, Uint8 *stream, int len) {
  AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;
  int len1, audio_size;
  static uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE * 3) / 2];
  static unsigned int audio_buf_size = 0;
  static unsigned int audio_buf_index = 0;
  while(len > 0) {
    if(audio_buf_index >= audio_buf_size) {
      /* We have already sent all our data; get more */
      audio_size = audio_decode_frame(aCodecCtx, audio_buf, sizeof(audio_buf));
      if(audio_size < 0) {
  /* If error, output silence */
  audio_buf_size = 1024; // arbitrary?
  memset(audio_buf, 0, audio_buf_size);
      } else {
  audio_buf_size = audio_size;
      }
      audio_buf_index = 0;
    }
    len1 = audio_buf_size - audio_buf_index;
    if(len1 > len)
      len1 = len;
    fprintf(stderr, "index=%d, len1=%d, len=%d\n",
        audio_buf_index,
        len,
                    len1);
    memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);
    len -= len1;
    stream += len1;
    audio_buf_index += len1;
  }
}
int main(int argc, char *argv[]) {
  int       ret = -1;
  int             i, videoStream, audioStream;
  AVFormatContext *pFormatCtx = NULL;
  //for video decode
  AVCodecContext  *pCodecCtxOrig = NULL;
  AVCodecContext  *pCodecCtx = NULL;
  AVCodec         *pCodec = NULL;
  struct SwsContext *sws_ctx = NULL;
  AVPicture   *pict = NULL;
  AVFrame         *pFrame = NULL;
  AVPacket        packet;
  int             frameFinished;
  //for audio decode
  AVCodecContext  *aCodecCtxOrig = NULL;
  AVCodecContext  *aCodecCtx = NULL;
  AVCodec         *aCodec = NULL;
  int64_t in_channel_layout;
  int64_t out_channel_layout;
  //for video render
  int     w_width = 640;
  int       w_height = 480;
  int             pixformat;
  SDL_Rect        rect;
  SDL_Window      *win;
  SDL_Renderer    *renderer;
  SDL_Texture     *texture;
  //for event
  SDL_Event       event;
  //for audio
  SDL_AudioSpec   wanted_spec, spec;
  if(argc < 2) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Usage: command <file>");
    return ret;
  }
  // Register all formats and codecs
  av_register_all();
  if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Could not initialize SDL - %s\n", SDL_GetError());
    return ret;
  }
  // Open video file
  if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to open multi-media file");
    goto __FAIL; // Couldn't open file
  }
  // Retrieve stream information
  if(avformat_find_stream_info(pFormatCtx, NULL)<0) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't find stream information ");
    goto __FAIL;  
  }
  // Dump information about file onto standard error
  av_dump_format(pFormatCtx, 0, argv[1], 0);
  // Find the first video stream
  videoStream=-1;
  audioStream=-1;
  for(i=0; i<pFormatCtx->nb_streams; i++) {
    if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO &&
       videoStream < 0) {
      videoStream=i;
    }
    if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO &&
       audioStream < 0) {
      audioStream=i;
    }
  }
  if(videoStream==-1) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, " Didn't find a video stream ");
    goto __FAIL; // Didn't find a video stream
  }
  if(audioStream==-1) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, " Didn't find a audio stream ");
    goto __FAIL; // Didn't find a video stream
  }
  aCodecCtxOrig=pFormatCtx->streams[audioStream]->codec;
  aCodec = avcodec_find_decoder(aCodecCtxOrig->codec_id);
  if(!aCodec) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unsupported codec! ");
    goto __FAIL; // Didn't find a video stream
  }
  // Copy context
  aCodecCtx = avcodec_alloc_context3(aCodec);
  if(avcodec_copy_context(aCodecCtx, aCodecCtxOrig) != 0) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't copy codec context! ");
    goto __FAIL; // Didn't find a video stream
  }
  // Set audio settings from codec info
  wanted_spec.freq = aCodecCtx->sample_rate;
  wanted_spec.format = AUDIO_S16SYS;
  wanted_spec.channels = aCodecCtx->channels;
  wanted_spec.silence = 0;
  wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
  wanted_spec.callback = audio_callback;
  wanted_spec.userdata = aCodecCtx;
  if(SDL_OpenAudio(&wanted_spec, &spec) < 0) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to open audio device - %s!", SDL_GetError());
    goto __FAIL;
  }
  avcodec_open2(aCodecCtx, aCodec, NULL);
  packet_queue_init(&audioq);
  in_channel_layout = av_get_default_channel_layout(aCodecCtx->channels);
  out_channel_layout = in_channel_layout; //AV_CH_LAYOUT_STEREO;
  fprintf(stderr, "in layout:%lld, out layout:%lld \n", in_channel_layout, out_channel_layout);
  audio_convert_ctx = swr_alloc();
  if(audio_convert_ctx){
    swr_alloc_set_opts(audio_convert_ctx,
           out_channel_layout,
           AV_SAMPLE_FMT_S16,
           aCodecCtx->sample_rate,
           in_channel_layout,
           aCodecCtx->sample_fmt,
           aCodecCtx->sample_rate,
           0,
           NULL);
  }
  swr_init(audio_convert_ctx);
  SDL_PauseAudio(0);
  // Get a pointer to the codec context for the video stream
  pCodecCtxOrig=pFormatCtx->streams[videoStream]->codec;
  // Find the decoder for the video stream
  pCodec=avcodec_find_decoder(pCodecCtxOrig->codec_id);
  if(pCodec==NULL) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unsupported codec!");
    goto __FAIL;
  }
  // Copy context
  pCodecCtx = avcodec_alloc_context3(pCodec);
  if(avcodec_copy_context(pCodecCtx, pCodecCtxOrig) != 0) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to copy context of codec!");
    goto __FAIL;
  }
  // Open codec
  if(avcodec_open2(pCodecCtx, pCodec, NULL)<0) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to open audio decoder!");
    goto __FAIL;
  }
  // Allocate video frame
  pFrame=av_frame_alloc();
  w_width = pCodecCtx->width;
  w_height = pCodecCtx->height;
  fprintf(stderr, "width:%d, height:%d\n", w_width, w_height);
  win = SDL_CreateWindow("Media Player",
       SDL_WINDOWPOS_UNDEFINED,
       SDL_WINDOWPOS_UNDEFINED,
       w_width, w_height,
       SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
  if(!win){
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create window!");
    goto __FAIL;
  }
  renderer = SDL_CreateRenderer(win, -1, 0);
  if(!renderer){
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create renderer!");
    goto __FAIL;
  }
  pixformat = SDL_PIXELFORMAT_IYUV;
  texture = SDL_CreateTexture(renderer, 
                              pixformat,
              SDL_TEXTUREACCESS_STREAMING,
            w_width,
            w_height);
  if(!texture){
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create Texture!");
    goto __FAIL;
  }
  // initialize SWS context for software scaling
  sws_ctx = sws_getContext(pCodecCtx->width,
         pCodecCtx->height,
         pCodecCtx->pix_fmt,
         pCodecCtx->width,
         pCodecCtx->height,
         AV_PIX_FMT_YUV420P,
         SWS_BILINEAR,
         NULL,
         NULL,
         NULL);
  pict = (AVPicture*)malloc(sizeof(AVPicture));
  avpicture_alloc(pict,
                  AV_PIX_FMT_YUV420P,
                  pCodecCtx->width,
                  pCodecCtx->height);
  // Read frames and save first five frames to disk
  while(av_read_frame(pFormatCtx, &packet)>=0) {
    // Is this a packet from the video stream?
    if(packet.stream_index==videoStream) {
      // Decode video frame
      avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
      // Did we get a video frame?
      if(frameFinished) {
  // Convert the image into YUV format that SDL uses  
  sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,
      pFrame->linesize, 0, pCodecCtx->height,
      pict->data, pict->linesize);
  SDL_UpdateYUVTexture(texture, NULL,
                             pict->data[0], pict->linesize[0],
           pict->data[1], pict->linesize[1],
           pict->data[2], pict->linesize[2]);
  rect.x = 0;
  rect.y = 0;
  rect.w = pCodecCtx->width;
  rect.h = pCodecCtx->height;
  SDL_RenderClear(renderer);
  SDL_RenderCopy(renderer, texture, NULL, &rect);
  SDL_RenderPresent(renderer);
  av_free_packet(&packet);
      }
    } else if(packet.stream_index==audioStream) { //for audio
      packet_queue_put(&audioq, &packet);
    } else {
      av_free_packet(&packet);
    }
    // Free the packet that was allocated by av_read_frame
    SDL_PollEvent(&event);
    switch(event.type) {
    case SDL_QUIT:
      quit = 1;
      goto __QUIT; 
      break;
    default:
      break;
    }
  }
__QUIT:
  ret = 0;
__FAIL:
  // Free the YUV frame
  if(pFrame){
    av_frame_free(&pFrame);
  }
  // Close the codecs
  if(pCodecCtxOrig){
    avcodec_close(pCodecCtxOrig);
  }
  if(pCodecCtx){
    avcodec_close(pCodecCtx);
  }
  if(aCodecCtxOrig) {
    avcodec_close(aCodecCtxOrig);
  }
  if(aCodecCtx) {
    avcodec_close(aCodecCtx);
  }
  // Close the video file
  if(pFormatCtx){
    avformat_close_input(&pFormatCtx);
  }
  if(pict){
    avpicture_free(pict);
    free(pict);
  }
  if(win){
    SDL_DestroyWindow(win);
  }
  if(renderer){
    SDL_DestroyRenderer(renderer);
  }
  if(texture){
    SDL_DestroyTexture(texture);
  }
  SDL_Quit();
  return ret;
}