Calculate a 'lfe balance' value for the specified volume with
* the specified channel map. The return value will range from
* -1.0f (no lfe) to +1.0f (only lfe), where 0.0f is balanced.
* If no value is applicable to this channel map the return value
* will always be 0.0f. See pa_channel_map_can_lfe_balance(). \since 8.0
Calculate a 'lfe balance' value for the specified volume with * the specified channel map. The return value will range from * -1.0f (no lfe) to +1.0f (only lfe), where 0.0f is balanced. * If no value is applicable to this channel map the return value * will always be 0.0f. See pa_channel_map_can_lfe_balance(). \since 8.0