Defined in avformat.h

typedef struct AVFormatParameters {
    AVRational time_base;
    int sample_rate;
    int channels;
    int width;
    int height;
    enum PixelFormat pix_fmt;
    int channel; /**< used to select dv channel */
#if LIBAVFORMAT_VERSION_INT < (52<<16)
    const char *device; /**< video, audio or DV device */
#endif
    const char *standard; /**< tv standard, NTSC, PAL, SECAM */
    int mpeg2ts_raw:1;  /**< force raw MPEG2 transport stream output, if possible */
    int mpeg2ts_compute_pcr:1; /**< compute exact PCR for each transport
                                  stream packet (only meaningful if
                                  mpeg2ts_raw is TRUE) */
    int initial_pause:1;       /**< do not begin to play the stream
                                  immediately (RTSP only) */
    int prealloced_context:1;
    enum CodecID video_codec_id;
    enum CodecID audio_codec_id;
} AVFormatParameters;

av_set_parameters()