player_example.c

mediastreamer2是开源的网络传输媒体流的库

        len=tc->comment_lengths[i];
        value=malloc(len+1);
        memcpy(value,tc->user_comments[i],len);
        value[len]='\0';
        fprintf(out, "\t%s\n", value);
        free(value);
      }
    }
  }
  return(0);
}

/* Report the encoder-specified colorspace for the video, if any.
   We don't actually make use of the information in this example;
   a real player should attempt to perform color correction for
   whatever display device it supports. */
static void report_colorspace(theora_info *ti)
{
    switch(ti->colorspace){
      case OC_CS_UNSPECIFIED:
        /* nothing to report */
        break;;
      case OC_CS_ITU_REC_470M:
        fprintf(stderr,"  encoder specified ITU Rec 470M (NTSC) color.\n");
        break;;
      case OC_CS_ITU_REC_470BG:
        fprintf(stderr,"  encoder specified ITU Rec 470BG (PAL) color.\n");
        break;;
      default:
        fprintf(stderr,"warning: encoder specified unknown colorspace (%d).\n",
            ti->colorspace);
        break;;
    }
}

/* helper: push a page into the appropriate steam */
/* this can be done blindly; a stream won't accept a page
                that doesn't belong to it */
static int queue_page(ogg_page *page){
  if(theora_p)ogg_stream_pagein(&to,&og);
  if(vorbis_p)ogg_stream_pagein(&vo,&og);
  return 0;
}

static void usage(void){
  fprintf(stderr,
          "Usage: player_example <file.ogg>\n"
          "input is read from stdin if no file is passed on the command line\n"
          "\n"
  );
}

int main(int argc,char *argv[]){

  int i,j;
  ogg_packet op;

  FILE *infile = stdin;

#ifdef _WIN32 /* We need to set stdin/stdout to binary mode. Damn windows. */
  /* Beware the evil ifdef. We avoid these where we can, but this one we
     cannot. Don't add any more, you'll probably go to hell if you do. */
  _setmode( _fileno( stdin ), _O_BINARY );
#endif

  /* open the input file if any */
  if(argc==2){
    infile=fopen(argv[1],"rb");
    if(infile==NULL){
      fprintf(stderr,"Unable to open '%s' for playback.\n", argv[1]);
      exit(1);
    }
  }
  if(argc>2){
      usage();
      exit(1);
  }

  /* start up Ogg stream synchronization layer */
  ogg_sync_init(&oy);

  /* init supporting Vorbis structures needed in header parsing */
  vorbis_info_init(&vi);
  vorbis_comment_init(&vc);

  /* init supporting Theora structures needed in header parsing */
  theora_comment_init(&tc);
  theora_info_init(&ti);

  /* Ogg file open; parse the headers */
  /* Only interested in Vorbis/Theora streams */
  while(!stateflag){
    int ret=buffer_data(infile,&oy);
    if(ret==0)break;
    while(ogg_sync_pageout(&oy,&og)>0){
      ogg_stream_state test;

      /* is this a mandated initial header? If not, stop parsing */
      if(!ogg_page_bos(&og)){
        /* don't leak the page; get it into the appropriate stream */
        queue_page(&og);
        stateflag=1;
        break;
      }

      ogg_stream_init(&test,ogg_page_serialno(&og));
      ogg_stream_pagein(&test,&og);
      ogg_stream_packetout(&test,&op);

      /* identify the codec: try theora */
      if(!theora_p && theora_decode_header(&ti,&tc,&op)>=0){
        /* it is theora */
        memcpy(&to,&test,sizeof(test));
        theora_p=1;
      }else if(!vorbis_p && vorbis_synthesis_headerin(&vi,&vc,&op)>=0){
        /* it is vorbis */
        memcpy(&vo,&test,sizeof(test));
        vorbis_p=1;
      }else{
        /* whatever it is, we don't care about it */
        ogg_stream_clear(&test);
      }
    }
    /* fall through to non-bos page parsing */
  }

  /* we're expecting more header packets. */
  while((theora_p && theora_p<3) || (vorbis_p && vorbis_p<3)){
    int ret;

    /* look for further theora headers */
    while(theora_p && (theora_p<3) && (ret=ogg_stream_packetout(&to,&op))){
      if(ret<0){
        fprintf(stderr,"Error parsing Theora stream headers; corrupt stream?\n");
        exit(1);
      }
      if(theora_decode_header(&ti,&tc,&op)){
        printf("Error parsing Theora stream headers; corrupt stream?\n");
        exit(1);
      }
      theora_p++;
      if(theora_p==3)break;
    }

    /* look for more vorbis header packets */
    while(vorbis_p && (vorbis_p<3) && (ret=ogg_stream_packetout(&vo,&op))){
      if(ret<0){
        fprintf(stderr,"Error parsing Vorbis stream headers; corrupt stream?\n");
        exit(1);
      }
      if(vorbis_synthesis_headerin(&vi,&vc,&op)){
        fprintf(stderr,"Error parsing Vorbis stream headers; corrupt stream?\n");
        exit(1);
      }
      vorbis_p++;
      if(vorbis_p==3)break;
    }

    /* The header pages/packets will arrive before anything else we
       care about, or the stream is not obeying spec */

    if(ogg_sync_pageout(&oy,&og)>0){
      queue_page(&og); /* demux into the appropriate stream */
    }else{
      int ret=buffer_data(infile,&oy); /* someone needs more data */
      if(ret==0){
        fprintf(stderr,"End of file while searching for codec headers.\n");
        exit(1);
      }
    }
  }

  /* and now we have it all.  initialize decoders */
  if(theora_p){
    theora_decode_init(&td,&ti);
    printf("Ogg logical stream %x is Theora %dx%d %.02f fps",
           (unsigned int)to.serialno,ti.width,ti.height, 
           (double)ti.fps_numerator/ti.fps_denominator);
    switch(ti.pixelformat){
      case OC_PF_420: printf(" 4:2:0 video\n"); break;
      case OC_PF_422: printf(" 4:2:2 video\n"); break;
      case OC_PF_444: printf(" 4:4:4 video\n"); break;
      case OC_PF_RSVD:
      default:
	printf(" video\n  (UNKNOWN Chroma sampling!)\n");
	break;
    }
    if(ti.width!=ti.frame_width || ti.height!=ti.frame_height)
      printf("  Frame content is %dx%d with offset (%d,%d).\n",
           ti.frame_width, ti.frame_height, ti.offset_x, ti.offset_y);
    report_colorspace(&ti);
    dump_comments(&tc);
  }else{
    /* tear down the partial theora setup */
    theora_info_clear(&ti);
    theora_comment_clear(&tc);
  }
  if(vorbis_p){
    vorbis_synthesis_init(&vd,&vi);
    vorbis_block_init(&vd,&vb);
    fprintf(stderr,"Ogg logical stream %x is Vorbis %d channel %d Hz audio.\n",
            (unsigned int)vo.serialno,vi.channels,(int)vi.rate);
  }else{
    /* tear down the partial vorbis setup */
    vorbis_info_clear(&vi);
    vorbis_comment_clear(&vc);
  }

  /* open audio */
  if(vorbis_p)open_audio();

  /* open video */
  if(theora_p)open_video();

  /* install signal handler as SDL clobbered the default */
  signal (SIGINT, sigint_handler);

  /* on to the main decode loop.  We assume in this example that audio
     and video start roughly together, and don't begin playback until
     we have a start frame for both.  This is not necessarily a valid
     assumption in Ogg A/V streams! It will always be true of the
     example_encoder (and most streams) though. */

  stateflag=0; /* playback has not begun */
  while(!got_sigint){

    /* we want a video and audio frame ready to go at all times.  If
       we have to buffer incoming, buffer the compressed data (ie, let
       ogg do the buffering) */
    while(vorbis_p && !audiobuf_ready){
      int ret;
      float **pcm;

      /* if there's pending, decoded audio, grab it */
      if((ret=vorbis_synthesis_pcmout(&vd,&pcm))>0){
        int count=audiobuf_fill/2;
        int maxsamples=(audiofd_fragsize-audiobuf_fill)/2/vi.channels;
        for(i=0;i<ret && i<maxsamples;i++)
          for(j=0;j<vi.channels;j++){
            int val=rint(pcm[j][i]*32767.f);
            if(val>32767)val=32767;
            if(val<-32768)val=-32768;
            audiobuf[count++]=val;
          }
        vorbis_synthesis_read(&vd,i);
        audiobuf_fill+=i*vi.channels*2;
        if(audiobuf_fill==audiofd_fragsize)audiobuf_ready=1;
        if(vd.granulepos>=0)
          audiobuf_granulepos=vd.granulepos-ret+i;
        else
          audiobuf_granulepos+=i;
        
      }else{
        
        /* no pending audio; is there a pending packet to decode? */
        if(ogg_stream_packetout(&vo,&op)>0){
          if(vorbis_synthesis(&vb,&op)==0) /* test for success! */
            vorbis_synthesis_blockin(&vd,&vb);
        }else   /* we need more data; break out to suck in another page */
          break;
      }
    }

    while(theora_p && !videobuf_ready){
      /* theora is one in, one out... */
      if(ogg_stream_packetout(&to,&op)>0){

        theora_decode_packetin(&td,&op);
        videobuf_granulepos=td.granulepos;
        
        videobuf_time=theora_granule_time(&td,videobuf_granulepos);

        /* is it already too old to be useful?  This is only actually
           useful cosmetically after a SIGSTOP.  Note that we have to
           decode the frame even if we don't show it (for now) due to
           keyframing.  Soon enough libtheora will be able to deal
           with non-keyframe seeks.  */

        if(videobuf_time>=get_time())
        videobuf_ready=1;
                
      }else
        break;
    }

    if(!videobuf_ready && !audiobuf_ready && feof(infile))break;

    if(!videobuf_ready || !audiobuf_ready){
      /* no data yet for somebody.  Grab another page */
      int bytes=buffer_data(infile,&oy);
      while(ogg_sync_pageout(&oy,&og)>0){
        queue_page(&og);
      }
    }

    /* If playback has begun, top audio buffer off immediately. */
    if(stateflag) audio_write_nonblocking();

    /* are we at or past time for this video frame? */
    if(stateflag && videobuf_ready && videobuf_time<=get_time()){
      video_write();
      videobuf_ready=0;
    }

    if(stateflag &&
       (audiobuf_ready || !vorbis_p) &&
       (videobuf_ready || !theora_p) &&
       !got_sigint){
      /* we have an audio frame ready (which means the audio buffer is
         full), it's not time to play video, so wait until one of the
         audio buffer is ready or it's near time to play video */
        
      /* set up select wait on the audiobuffer and a timeout for video */
      struct timeval timeout;
      fd_set writefs;
      fd_set empty;
      int n=0;

      FD_ZERO(&writefs);
      FD_ZERO(&empty);
      if(audiofd>=0){
        FD_SET(audiofd,&writefs);
        n=audiofd+1;
      }

      if(theora_p){
        long milliseconds=(videobuf_time-get_time())*1000-5;
        if(milliseconds>500)milliseconds=500;
        if(milliseconds>0){
          timeout.tv_sec=milliseconds/1000;
          timeout.tv_usec=(milliseconds%1000)*1000;

          n=select(n,&empty,&writefs,&empty,&timeout);
          if(n)audio_calibrate_timer(0);
        }
      }else{
        select(n,&empty,&writefs,&empty,NULL);
      }
    }

    /* if our buffers either don't exist or are ready to go,
       we can begin playback */
    if((!theora_p || videobuf_ready) &&
       (!vorbis_p || audiobuf_ready))stateflag=1;
    /* same if we've run out of input */
    if(feof(infile))stateflag=1;

  }

  /* tear it all down */

  audio_close();
  SDL_Quit();

  if(vorbis_p){
    ogg_stream_clear(&vo);
    vorbis_block_clear(&vb);
    vorbis_dsp_clear(&vd);
    vorbis_comment_clear(&vc);
    vorbis_info_clear(&vi);
  }
  if(theora_p){
    ogg_stream_clear(&to);
    theora_clear(&td);
    theora_comment_clear(&tc);
    theora_info_clear(&ti);
  }
  ogg_sync_clear(&oy);

  if(infile && infile!=stdin)fclose(infile);

  fprintf(stderr,
          "\r                                                              "
          "\nDone.\n");
  return(0);

}