int get_video_info(int track, int &pid, double &framerate,
int &width, int &height, char *title=0);
int get_audio_for_video(int vstream, int astream, int64_t &channel_mask);
int get_video_info(int track, int &pid, double &framerate,
int &width, int &height, char *title=0);
int get_audio_for_video(int vstream, int astream, int64_t &channel_mask);