scripts/s_region_gain.lua

   1 ardour { ["type"] = "Snippet", name = "Set Region Gain" }
   2
   3 function factory () return function ()
   4         -- get Editor GUI Selection
   5         -- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:Selection
   6         local sel = Editor:get_selection ()
   7
   8         -- allocate a buffer (float* in C)
   9         -- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:DspShm
  10         local cmem = ARDOUR.DSP.DspShm (8192)
  11
  12         -- prepare undo operation
  13         Session:begin_reversible_command ("Lua Region Gain")
  14         local add_undo = false -- keep track if something has changed
  15
  16         -- iterate over selected regions
  17         -- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:RegionSelection
  18         for r in sel.regions:regionlist ():iter () do
  19                 -- test if it's an audio region
  20                 if r:to_audioregion ():isnil () then
  21                         goto next
  22                 end
  23
  24                 -- to read the Region data, we use the Readable interface of the Region
  25                 -- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:Readable
  26                 local rd = r:to_readable ()
  27
  28                 local n_samples = rd:readable_length ()
  29                 local n_channels = rd:n_channels ()
  30
  31                 local peak = 0 -- the audio peak to be calculated
  32
  33                 -- iterate over all channels in Audio Region
  34                 for c = 0, n_channels do
  35                         repeat
  36                                 local pos = 0
  37                                 -- read at most 8K samples of channel 'c'
  38                                 local s = rd:read (cmem:to_float (0), pos, 8192, c)
  39                                 pos = pos + s
  40                                 -- access the raw audio data
  41                                 -- http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray
  42                                 local d = cmem:to_float (0):array()
  43                                 -- iterate over the audio sample data
  44                                 for i = 0, s do
  45                                         if math.abs (d[i]) > peak then
  46                                                 peak = math.abs (d[i])
  47                                         end
  48                                 end
  49                         until pos < n_samples
  50                 end
  51
  52                 if (peak > 0) then
  53                         print ("Region:", r:name (), "peak:", 20 * math.log (peak) / math.log(10), "dBFS")
  54                 else
  55                         print ("Region:", r:name (), " is silent")
  56                 end
  57
  58                 -- normalize region
  59                 if (peak > 0) then
  60                         -- prepare for undo
  61                         r:to_stateful ():clear_changes ()
  62                         -- apply gain
  63                         r:to_audioregion (): set_scale_amplitude (1 / peak)
  64                         -- save changes (if any) to undo command
  65                         if not Session:add_stateful_diff_command (r:to_statefuldestructible ()):empty () then
  66                                 add_undo = true
  67                         end
  68                 end
  69
  70                 ::next::
  71         end
  72
  73         -- all done. now commit the combined undo operation
  74         if add_undo then
  75                 -- the 'nil' command here means to use all collected diffs
  76                 Session:commit_reversible_command (nil)
  77         else
  78                 Session:abort_reversible_command ()
  79         end
  80
  81 end end