ardour { ["type"] = "Snippet", name = "Set Region Gain" } function factory () return function () -- get Editor GUI Selection -- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:Selection local sel = Editor:get_selection () -- allocate a buffer (float* in C) -- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:DspShm local cmem = ARDOUR.DSP.DspShm (8192) -- prepare undo operation Session:begin_reversible_command ("Lua Region Gain") local add_undo = false -- keep track if something has changed -- iterate over selected regions -- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:RegionSelection for r in sel.regions:regionlist ():iter () do -- test if it's an audio region if r:to_audioregion ():isnil () then goto next end -- to read the Region data, we use the Readable interface of the Region -- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:Readable local rd = r:to_readable () local n_samples = rd:readable_length () local n_channels = rd:n_channels () local peak = 0 -- the audio peak to be calculated -- iterate over all channels in Audio Region for c = 0, n_channels do repeat local pos = 0 -- read at most 8K samples of channel 'c' local s = rd:read (cmem:to_float (0), pos, 8192, c) pos = pos + s -- access the raw audio data -- http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray local d = cmem:to_float (0):array() -- iterate over the audio sample data for i = 0, s do if math.abs (d[i]) > peak then peak = math.abs (d[i]) end end until pos < n_samples end if (peak > 0) then print ("Region:", r:name (), "peak:", 20 * math.log (peak) / math.log(10), "dBFS") else print ("Region:", r:name (), " is silent") end -- normalize region if (peak > 0) then -- prepare for undo r:to_stateful ():clear_changes () -- apply gain r:to_audioregion (): set_scale_amplitude (1 / peak) -- save changes (if any) to undo command if not Session:add_stateful_diff_command (r:to_statefuldestructible ()):empty () then add_undo = true end end ::next:: end -- all done. now commit the combined undo operation if add_undo then -- the 'nil' command here means to use all collected diffs Session:commit_reversible_command (nil) else Session:abort_reversible_command () end end end