Combining Midi Files

Question

I have a list of imported midi files, as Sound objects. I simply want to string them together. I've tried a lot of things and nothing has worked, apart from a hack-y version of manipulating the midi's as strings, which is needlessly over complicated.

Is there an easy way to combine sound objects like this?

Answer 1

Here is an answer using Audio and AudioData.

dirName = "~/some/dir/name/";
Export[dirName <> "sequence.mid", 
  Sound[SoundNote[#, 1.75, "Trumpet"] & /@ {0, 7, 12}]];

Export[dirName <> "perc.mid", 
  Sound[SoundNote["RideCymbal", #] & /@ {0.26, 0.1, 0.26, 0.1, 2}]];

mid1 = Import[dirName <> "perc.mid"];
mid2 = Import[dirName <> "sequence.mid"];

fs = 44000;

ams = Audio[#, SampleRate -> fs] & /@ {mid1, mid2}

Map[Dimensions, AudioData /@ ams]
(* {{2, 119872}, {2, 232064}} *)

AudioPlot /@ ams

am2 = MapThread[Join, AudioData /@ ams];
Dimensions[am2]
(* {2, 351936} *)

This does the sequential combination of midi objects:

Audio[am2]

This shows the sequential combination of midi objects with AudioPlot.

AudioPlot[Audio[am2]]

Answer 2

Explanation

Sound can combine the two sound sequences:

Sound[{s1, s2}]

the problem you may be facing is that if you do

Sound[{Import["file1.mid"], Import["file2.mid"]}]

Is that they may play sequentially, one after the other, and not at the same time. That is, unless you specify the initial and final time.

Therefore this would work

Sound[
 {
  Sound[Import["file1.mid"], {0, duration1}],
  Sound[Import["file2.mid"], {0, duration2}]
  }
 ]

To get the duration time you may do

duration1= Import["file1.mid", {"MIDI", "Duration"}]

Solution

mixMIDI[fl_] := Sound[
  Table[
   Module[{
     mf = Import[file, "MIDI"],
     duration = Import[file, {"MIDI", "Duration"}]
     },
    Sound[mf, {0, duration}]
    ]
   , {file, fl}]
  ]

mixMIDI@FileNames["*.mid"]

Example ("Thus Spake Zarathustra")

Export["Bassoon.mid", 
 Sound[{SoundNote["C1", {0.10, 13.13}, "Bassoon", SoundVolume -> 1]}]]

Export["CrashCymbal.mid", 
 Sound[{SoundNote["CrashCymbal", {12.17, 13.48},  SoundVolume -> 1]}]]

Export[
 "FrenchHorn.mid",
 Sound@Map[
   SoundNote[Sequence @@ #, "FrenchHorn", 
     SoundVolume -> 1] &, {{"G3", {11.873005866666666`, 
      12.0371849`}}, {"G3", {12.23867735`, 
      15.850616083333332`}}, {"C4", {4.059321424999999`, 
      5.949151649999996`}}, {"G4", {6.169490599999996`, 
      7.999998799999996`}}, {"C5", {8.211863174999994`, 
      11.537185116666672`}}, {"C4", {11.828229766666672`, 
      11.925244650000005`}}, {"E4", {11.828229766666672`, 
      11.932707333333338`}}, {"G4", {11.820767083333338`, 
      11.955095383333338`}}, {"C4", {12.193901250000005`, 
      15.895392183333337`}}, {"G4", {12.193901250000005`, 
      15.895392183333337`}}, {"D#4", {12.201363933333338`, 
      15.910317550000004`}}}
   ]]

 Export[
 "BrassSection.mid",
 Sound@Map[
   SoundNote[Sequence @@ #, "BrassSection", 
     SoundVolume -> 1] &, {{"C4", {4.059321424999999`, 
      5.949151649999997`}}, {"G4", {6.169490599999997`, 
      7.999998799999997`}}, {"C5", {8.211863174999998`, 
      11.537185116666675`}}, {"C5", {11.828229766666675`, 
      11.925244650000009`}}, {"E5", {11.828229766666675`, 
      11.932707333333342`}}, {"G4", {11.820767083333342`, 
      11.955095383333342`}}, {"C5", {12.193901250000009`, 
      15.89539218333334`}}, {"G4", {12.193901250000009`, 
      15.89539218333334`}}, {"D#5", {12.201363933333342`, 
      15.910317550000007`}}}
   ]]

 Export[
 "Timpani.mid",
 Sound@Map[
   SoundNote[Sequence @@ #, "Timpani", 
     SoundVolume -> 1] &, {{"C3", {13.932706466666666`, 
      13.992407933333332`}}, {"D3", {14.007333299999999`, 
      14.059572083333332`}}, {"C3", {14.111810866666666`, 
      14.141661599999999`}}, {"D3", {14.164049649999999`, 
      14.208825749999999`}}, {"C3", {14.246139166666666`, 
      14.283452583333332`}}, {"D3", {14.298377949999999`, 
      14.350616733333332`}}, {"C3", {14.373004783333332`, 
      14.417780883333332`}}, {"D3", {14.425243566666666`, 
      14.484945033333332`}}, {"C3", {14.507333083333332`, 
      14.559571866666666`}}, {"D3", {14.567034549999999`, 
      14.619273333333332`}}, {"C3", {14.634198699999999`, 
      14.678974799999999`}}, {"D3", {14.693900166666666`, 
      14.746138949999999`}}, {"C3", {14.768526999999999`, 
      14.820765783333332`}}, {"D3", {14.820765783333332`, 
      14.873004566666665`}}, {"C3", {14.887929933333332`, 
      14.940168716666665`}}, {"D3", {14.955094083333332`, 
      15.007332866666665`}}, {"C3", {15.022258233333332`, 
      15.074497016666665`}}, {"D3", {15.074497016666665`, 
      15.126735799999999`}}, {"C3", {15.149123849999999`, 
      15.193899949999999`}}, {"D3", {15.201362633333332`, 
      15.253601416666665`}}, {"C3", {15.268526783333332`, 
      15.313302883333332`}}, {"D3", {15.320765566666665`, 
      15.365541666666665`}}, {"C3", {15.387929716666665`, 
      15.440168499999999`}}, {"D3", {15.440168499999999`, 
      15.484944599999999`}}, {"C3", {15.514795333333332`, 
      15.567034116666665`}}, {"D3", {15.559571433333332`, 
      15.611810216666665`}}, {"C3", {15.634198266666665`, 
      15.656586316666665`}}, {"C3", {15.738675833333332`, 
      15.828228033333332`}}, {"G2", {16.014795116666665`, 
      16.09688463333333`}}, {"C3", {16.2909144`, 
      16.3804666`}}, {"G2", {16.574496366666665`, 
      16.67151125`}}, {"C3", {16.850615649999998`, 
      16.932705166666665`}}, {"G2", {17.141660299999998`, 
      17.23867518333333`}}, {"C3", {17.425242266666665`, 
      17.50733178333333`}}, {"G2", {17.723749599999998`, 
      17.813301799999998`}}, {"C3", {18.007331566666664`, 
      18.08942108333333`}}, {"G2", {18.328226949999998`, 
      18.417779149999998`}}, {"C3", {18.62673428333333`, 
      18.708823799999998`}}, {"G2", {18.94016698333333`, 
      19.02971918333333`}}, {"C3", {19.290913099999997`, 
      19.484942866666664`}}}
   ]]

mixMIDI@{"Bassoon.mid", "BrassSection.mid", "FrenchHorn.mid", "CrashCymbal.mid", "Timpani.mid"}