函数 av_channel_layout_from_mask 

pub unsafe extern "C" fn av_channel_layout_from_mask(
    channel_layout: *mut AVChannelLayout,
    mask: u64,
) -> c_int

Initialize a native channel layout from a bitmask indicating which channels are present.

@param channel_layout the layout structure to be initialized @param mask bitmask describing the channel layout

@return 0 on success AVERROR(EINVAL) for invalid mask values