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livetrax/share/scripts/_find_nonzero_sample.lua

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ardour {
["type"] = "EditorAction",
name = "Find non zero audio sample",
author = "Ardour Team",
description = [[Find the position of first non-zero audio sample in selected regions.]]
}
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)
local msg = ""
-- 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 a = r.to_audioregion()
local rd = a:to_readable ()
local n_samples = rd:readable_length ()
local n_channels = rd:n_channels ()
local nonzeropos = -1
-- iterate over all channels in Audio Region
for c = 0, n_channels -1 do
local pos = 0
repeat
-- read at most 8K samples of channel 'c' starting at 'pos'
local s = rd:read (cmem:to_float (0), pos, 8192, c)
-- 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 = 1, s do
if math.abs (d[i]) > 0 then
if (nonzeropos < 0 or pos + i < nonzeropos) then
nonzeropos = pos + i - 1
end
break
end
end
pos = pos + s
if (nonzeropos >= 0 and pos > nonzeropos) then
break
end
until s < 8192
end
if (nonzeropos >= 0) then
msg = msg .. string.format("%s: %d\n", r:name (), nonzeropos + r:position())
else
msg = msg .. "Region: '%s' is silent\n"
end
::next::
end
if (msg ~= "") then
local md = LuaDialog.Message ("First Non Zero Sample", msg, LuaDialog.MessageType.Info, LuaDialog.ButtonType.Close)
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md:run()
end
end end