if (SDL_OpenAudio(&wanted_spec, NULL)<0)//步骤（2）打开音频设备
{
printf("can't open audio.\n");
return 0;
}
//-----------------------------------------------------
printf("比特率 %3d\n", pFormatCtx->bit_rate);
printf("解码器名称 %s\n", pCodecCtx->codec->long_name);
printf("time_base %d \n", pCodecCtx->time_base);
printf("声道数 %d \n", pCodecCtx->channels);
printf("sample per second %d \n", pCodecCtx->sample_rate);
//新版不再需要
