函数 av_channel_name 

pub unsafe extern "C" fn av_channel_name(
    buf: *mut c_char,
    buf_size: usize,
    channel: AVChannel,
) -> c_int

Get a human readable string in an abbreviated form describing a given channel. This is the inverse function of @ref av_channel_from_string().

@param buf pre-allocated buffer where to put the generated string @param buf_size size in bytes of the buffer. @param channel the AVChannel whose name to get @return amount of bytes needed to hold the output string, or a negative AVERROR on failure. If the returned value is bigger than buf_size, then the string was truncated.