+/**
+ * Return the payload type for a given stream used in the given format context.
+ * Static payload types are derived from the codec.
+ * Dynamic payload type are derived from the id field in AVStream.
+ * The format context private option payload_type overrides both.
+ *
+ * @param fmt The context of the format
+ * @param par The codec parameters
+ * @param idx The stream index
+ * @return The payload type (the 'PT' field in the RTP header).
+ */
+int ff_rtp_get_payload_type(AVFormatContext *fmt, AVCodecParameters *par,
+ int idx);
+
+/**
+ * Initialize a codec context based on the payload type.
+ *
+ * Fill the codec_type and codec_id fields of a codec context with
+ * information depending on the payload type; for audio codecs, the
+ * channels and sample_rate fields are also filled.
+ *
+ * @param par The codec parameters
+ * @param payload_type The payload type (the 'PT' field in the RTP header)
+ * @return In case of unknown payload type or dynamic payload type, a
+ * negative value is returned; otherwise, 0 is returned
+ */
+int ff_rtp_get_codec_info(AVCodecParameters *par, int payload_type);
+
+/**
+ * Return the encoding name (as defined in
+ * http://www.iana.org/assignments/rtp-parameters) for a given payload type.
+ *
+ * @param payload_type The payload type (the 'PT' field in the RTP header)
+ * @return In case of unknown payload type or dynamic payload type, a pointer
+ * to an empty string is returned; otherwise, a pointer to a string containing
+ * the encoding name is returned
+ */
+const char *ff_rtp_enc_name(int payload_type);
+
+/**
+ * Return the codec id for the given encoding name and codec type.
+ *
+ * @param buf A pointer to the string containing the encoding name
+ * @param codec_type The codec type
+ * @return In case of unknown encoding name, AV_CODEC_ID_NONE is returned;
+ * otherwise, the codec id is returned
+ */
+enum AVCodecID ff_rtp_codec_id(const char *buf, enum AVMediaType codec_type);