- * Parse AC-3 frame header.
- * Parse the header up to the lfeon element, which is the first 52 or 54 bits
- * depending on the audio coding mode.
- * @param[in] gbc BitContext containing the first 54 bits of the frame.
- * @param[out] hdr Pointer to struct where header info is written.
- * @return Returns 0 on success, -1 if there is a sync word mismatch,
- * -2 if the bsid (version) element is invalid, -3 if the fscod (sample rate)
- * element is invalid, or -4 if the frmsizecod (bit rate) element is invalid.