Get the index of a channel in channel_layout.
@param channel a channel layout describing exactly one channel which must be present in channel_layout.
@return index of channel in channel_layout on success, a negative AVERROR on error.
See Implementation
Get the index of a channel in channel_layout.
@param channel a channel layout describing exactly one channel which must be present in channel_layout.
@return index of channel in channel_layout on success, a negative AVERROR on error.