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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
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