// tutorial03.c// A pedagogical video player that will stream through every video frame as fast as it can// and play audio (out of sync).//// Code based on FFplay, Copyright (c) 2003 Fabrice Bellard, // and a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)// Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1// Use//// gcc -o tutorial03 tutorial03.c -lavutil -lavformat -lavcodec -lz -lm `sdl-config --cflags --libs`// to build (assuming libavformat and libavcodec are correctly installed, // and assuming you have sdl-config. Please refer to SDL docs for your installation.)//// Run using// tutorial03 myvideofile.mpg//// to play the stream on your screen.#include <avcodec.h>#include <avformat.h>#include <SDL.h>#include <SDL_thread.h>#ifdef __MINGW32__#undef main /* Prevents SDL from overriding main() */#endif#include <stdio.h>#define SDL_AUDIO_BUFFER_SIZE 1024typedef 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;}static 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;  int len1, data_size;  for(;;) {    while(audio_pkt_size > 0) {      data_size = buf_size;      len1 = avcodec_decode_audio2(aCodecCtx, (int16_t *)audio_buf, &data_size, 				  audio_pkt_data, audio_pkt_size);      if(len1 < 0) {	/* if error, skip frame */	audio_pkt_size = 0;	break;      }      audio_pkt_data += len1;      audio_pkt_size -= len1;      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[(AVCODEC_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;    memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);    len -= len1;    stream += len1;    audio_buf_index += len1;  }}int main(int argc, char *argv[]) {  AVFormatContext *pFormatCtx;  int             i, videoStream, audioStream;  AVCodecContext  *pCodecCtx;  AVCodec         *pCodec;  AVFrame         *pFrame;   AVPacket        packet;  int             frameFinished;  float           aspect_ratio;    AVCodecContext  *aCodecCtx;  AVCodec         *aCodec;  SDL_Overlay     *bmp;  SDL_Surface     *screen;  SDL_Rect        rect;  SDL_Event       event;  SDL_AudioSpec   wanted_spec, spec;  if(argc < 2) {    fprintf(stderr, "Usage: test <file>\n");    exit(1);  }  // Register all formats and codecs  av_register_all();    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {    fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());    exit(1);  }  // Open video file  if(av_open_input_file(&pFormatCtx, argv[1], NULL, 0, NULL)!=0)    return -1; // Couldn't open file    // Retrieve stream information  if(av_find_stream_info(pFormatCtx)<0)    return -1; // Couldn't find stream information    // Dump information about file onto standard error  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==CODEC_TYPE_VIDEO &&       videoStream < 0) {      videoStream=i;    }    if(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_AUDIO &&       audioStream < 0) {      audioStream=i;    }  }  if(videoStream==-1)    return -1; // Didn't find a video stream  if(audioStream==-1)    return -1;     aCodecCtx=pFormatCtx->streams[audioStream]->codec;  // 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) {    fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());    return -1;  }  aCodec = avcodec_find_decoder(aCodecCtx->codec_id);  if(!aCodec) {    fprintf(stderr, "Unsupported codec!\n");    return -1;  }  avcodec_open(aCodecCtx, aCodec);  // audio_st = pFormatCtx->streams[index]  packet_queue_init(&audioq);  SDL_PauseAudio(0);  // Get a pointer to the codec context for the video stream  pCodecCtx=pFormatCtx->streams[videoStream]->codec;    // Find the decoder for the video stream  pCodec=avcodec_find_decoder(pCodecCtx->codec_id);  if(pCodec==NULL) {    fprintf(stderr, "Unsupported codec!\n");    return -1; // Codec not found  }  // Open codec  if(avcodec_open(pCodecCtx, pCodec)<0)    return -1; // Could not open codec    // Allocate video frame  pFrame=avcodec_alloc_frame();  // Make a screen to put our video#ifndef __DARWIN__        screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);#else        screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);#endif  if(!screen) {    fprintf(stderr, "SDL: could not set video mode - exiting\n");    exit(1);  }    // Allocate a place to put our YUV image on that screen  bmp = SDL_CreateYUVOverlay(pCodecCtx->width,				 pCodecCtx->height,				 SDL_YV12_OVERLAY,				 screen);  // Read frames and save first five frames to disk  i=0;  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_video(pCodecCtx, pFrame, &frameFinished, 			   packet.data, packet.size);            // Did we get a video frame?      if(frameFinished) {	SDL_LockYUVOverlay(bmp);	AVPicture pict;	pict.data[0] = bmp->pixels[0];	pict.data[1] = bmp->pixels[2];	pict.data[2] = bmp->pixels[1];	pict.linesize[0] = bmp->pitches[0];	pict.linesize[1] = bmp->pitches[2];	pict.linesize[2] = bmp->pitches[1];	// Convert the image into YUV format that SDL uses	img_convert(&pict, PIX_FMT_YUV420P,                    (AVPicture *)pFrame, pCodecCtx->pix_fmt, 		    pCodecCtx->width, pCodecCtx->height);		SDL_UnlockYUVOverlay(bmp);		rect.x = 0;	rect.y = 0;	rect.w = pCodecCtx->width;	rect.h = pCodecCtx->height;	SDL_DisplayYUVOverlay(bmp, &rect);	av_free_packet(&packet);      }    } else if(packet.stream_index==audioStream) {      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;      SDL_Quit();      exit(0);      break;    default:      break;    }  }  // Free the YUV frame  av_free(pFrame);    // Close the codec  avcodec_close(pCodecCtx);    // Close the video file  av_close_input_file(pFormatCtx);    return 0;}