Are there variables such as global "time" , or sample "duration"

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Are there variables such as global “time” , or sample “duration”

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If you’d like to get the total number of seconds since the Epoch, or 1970-01-01 00:00:00 UTC, you can use Time.new.to_i, which comes from Ruby.

To get the duration of a sample in beats however, you don’t need to use Time. Instead, you can use sample_duration, which is built right into Sonic-Pi. You can find the details of this function and many others in the Lang tab of the Sonic-Pi Help documentation. Note the note: “avoid using sample_duration to set the sleep time in live_loops, prefer stretching the sample with the beat_stretch: opt or changing the BPM instead. See the examples below for details.”

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@d0lfyn happy in_thread anniversary! :birthday:

@lron - as also seen in the Lang reference tab, there are functions like vt, which give the virtual time of the current thread, and current_time, which behaves similar to Ruby Time.now with the exception that if used repeatedly with no sleeps or syncs in between, it returns the same value each time - and it is also affected by time_warp. What are you thinking of using a ‘global’ time value for? :slightly_smiling_face:

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Thanks for the info! I’m getting back into SonicPi after a long break. I want the time value to give me something I can hang on to while learning SP. I’m not a musician, thinking in beats and measures isn’t natural. I can relate to minutes and seconds. I find myself mentally converting beats into seconds.

It’s a crutch, but that’s how I think about time.

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Anytime! I’m also revisiting Sonic-Pi, which I want to integrate in my compositions. Anyways, you can use the bt function to convert beats to seconds.

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That actually helps, a lot!
Thanks

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7

Is there a function to convert a chord to intervals?

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The closest thing I can think of is to use the chord function which, given a tonic note and a chord name, returns a ring of MIDI notes. You can count the difference between each MIDI note to determine its interval in semitones.

For instance, if we run puts chord :A, :maj, we get the following output:

(ring <SonicPi::Chord :A :maj [69, 73, 76])

73 - 69 = 4 semitones, AKA a major third
76 - 73 = 3 semitones, AKA a minor third

Hope this helps!

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Thanks,
That worked fine.

intervals = chord( :A, :major )
intervals = intervals - intervals[0]
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Sorry but could you link to this documentation? I’m having a hard time locating it.

Would it be possible to use one of these time functions to set a duration that a certain portion should take? For example, play just one slow beat if a value is low, or play a lot of fast beats until the end of the time frame if a value is high? I hope that’s not too abstract to understand!

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Hi there!

The documentation is built right into the Sonic Pi editor. To my knowledge, it’s the only place you can find the most up-to-date documentation at the moment. Anyways, to get there, first click on the “help” icon amongst the upper-right icons of the editor.

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Then, in the container that opens up at the bottom of the editor, select the “Lang” tab.

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And to address your second question: my understanding of the problem based on your example is that your value is directly proportional to the number of beats to fit into the timeframe. I would therefore approach the problem like this:

# n.b. timeframe is in seconds
define :play_in_timeframe do |timeframe, num_beats|
  beat_duration = timeframe.to_f / num_beats
  
  num_beats.times do
    play :c4, attack: 0, decay: 0, sustain: beat_duration, release: 0
    sleep beat_duration
  end
end

play_in_timeframe(2, 8)

I could write a similar function for samples, by supplying a value for rate:.

# n.b. timeframe is in seconds
define :sample_in_timeframe do |sample_id, timeframe, num_beats|
  beat_duration = timeframe.to_f / num_beats
  new_rate = (sample_duration sample_id) / beat_duration
  
  num_beats.times do
    sample sample_id, rate: new_rate
    sleep beat_duration
  end
end

sample_in_timeframe(:bd_808, 2, 8)

I hope this helps!

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12

@datagrazer, @d0lfyn - there’s also a handy built-in function that will be helpful in this case :slight_smile: - density.
Try modifying the parameter (let’s call it d) for density here - the number causes the inner block to be repeated d times and the BPM of the block is also multiplied by d.

#  Play a note at 30 BPM, that lasts for 2 seconds, and sleep for 2 seconds
density(0.5) do
  play :c4, sustain: 1, release: 0
  sleep 1
end

# play two samples at 120 BPM, with a sleep of 0.5 seconds after each
density(2) do
  sample :bd_haus
  sleep 1
end

More details are in the help panel that d0lfyn refers to above, under the Lang category :+1:

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