change speed of WAV playback?

bnikkel · 2020-10-21 14:09

im using the wavplayer program with simpleIDE, is there anyway to speed up or slow down the playback speed of a wav track? thanks.

Phil Pilgrim (PhiPi) · 2020-10-21 18:13

With or without changing the pitch?

-Phil

bnikkel · 2020-10-21 20:08

im not sure really? its a diesel engine track and i am wanting it to simulate speeding up and slowing down

Rayman · 2020-10-21 20:14

Can you post the .spin file that plays the wav?

Usually this kind of code will read the .wav header to get the playback sample rate (and other things). Usually around 24 to 48 kHz.
If you can find this part of the code, just change this number to be higher or lower to change the playback speed...

JonnyMac · 2020-10-21 22:08

My WAV object (Spin) allows you to set the playback speed -- depending on the encoding rate -- between 50% and 200%. The point is, it can be done.

Clock Loop · 2020-10-21 22:52

I need to do the same thing with my engine railroad controller. The sounds need to be played back at different speeds, but have the pitch remain the same.

I figured the prop wasn't up to doing the pitch bending, so I decided to pitch bend the waves myself in a audio program, and save a bunch of them for different speeds.
And then play the set of waves for the speed I am running.

@JonnyMac does your object preserve the pitch? (i would imagine not?)

Rayman · 2020-10-21 22:56

That’s a neat trick... I’ve radio stations do that to speed up music and speech

Wonder if audacity can do that...

Clock Loop · 2020-10-21 23:00

Rayman wrote: »

Wonder if audacity can do that...

Actually it can.

Phil Pilgrim (PhiPi) · 2020-10-21 23:04

You may not get the results you expect from just varying the playback speed.

Think of a diesel engine as being like the human vocal tract. The pitch is controlled by the excitation of the vocal chords. In an engine, this would be the engine RPMs, which can vary up and down. But what gives speech its distinctive quality are the formants formed by resonances in the mouth and nasal cavity. These do not vary with pitch. In an engine, the formants are formed by resonances in the exhaust system: the manifold, exhaust pipe, muffler, and tailpipe. As with voice formants, these also do not change with pitch.

But adjusting the playback speed will change both the pitch and formant frequencies, rendering the engine with a different sound, rather than just revving higher. When this is done to a voice recording, you get Alvin and the Chipmunks, rather than hearing the same person singing at a higher pitch.

-Phil

Clock Loop · 2020-10-21 23:14

The music world seems to think autotune is ok, so why shouldn't we use it.

Someone needs to get the prop running autotune code!

What say you phil, you wanna code that monstrosity of pointless....
oh nevermind, im sure the science behind autotune is much more complicated and interesting than the actual results and uses FOR autotune.

I didn't find any autotuned train engines on youtube.

Perhaps a new autotune trend should be started.

JonnyMac · 2020-10-21 23:20

@JonnyMac does your object preserve the pitch? (i would imagine not?)

No. You would have to buffer and resample the audio -- there is not enough horsepower or RAM in the P1 for that.

Duane Degn · 2020-10-21 23:25

As Phil suggests, changing the playback speed will change the pitch of the sound.

YouTube manages to change playback speed without changing pitch but I'm pretty sure this requires a lot of processing power and some very clever algorithms. My guess is they're using fourier transformations and lots of newt eyes for that kind of magic.

JonnyMac · 2020-10-22 00:36

I'm betting that YouTube preprocess and saves multiple audio streams for each video file. Note that speed changes are at fixed rates. If you could vary the speed to any value on the fly I would believe they're doing it in real time.

Electrodude · 2020-10-24 02:32

JonnyMac wrote: »

I'm betting that YouTube preprocess and saves multiple audio streams for each video file. Note that speed changes are at fixed rates. If you could vary the speed to any value on the fly I would believe they're doing it in real time.

I'm betting they don't. YouTube recently added a "Custom" option that lets you set it to any arbitrary value. VLC has been able to do it in realtime for as long as I've used it.

whicker · 2020-10-24 05:54

Electrodude wrote: »

I'm betting they don't. YouTube recently added a "Custom" option that lets you set it to any arbitrary value. VLC has been able to do it in realtime for as long as I've used it.

Yeah, because we all run the youtube.exe application, just like VLC.exe

msrobots · 2020-10-24 22:27

well it is more the Chrome.exe rendering the audio and video stream it gets from youtube...

Mike

bnikkel · 2020-10-27 19:49

@Rayman the .spin file is audiosynth.spin and wont post because of the length, it was with the C file im using.

here is the begining of the spin file.

CON
    SAMPLES     = 512                                                           ' samples per cycle
    PERIOD      = 80_000_000 / 40_000                                           ' clkfreq / sample rate
    OSCILLATORS = 4                                                             ' hardcoded oscillators used by synthesizer

    #0, _SQUARE, _SAW, _TRIANGLE, _SINE, _NOISE, _SAMPLE                        ' waveform options
    #0, _ENV, _ATK, _DEC, _SUS, _REL, _WAV
    #0, _O, _A, _D, _S, _R
    'AUDIO       = 27
    'AUDIO2      = 26


VAR
    long    osc_sample         '0

    long    osc_envelope       '$01010101 
    long    osc_attack         '$7F7F7F7F
    long    osc_decay          '0
    long    osc_sustain        '$7F7F7F7F
    long    osc_release        '0
    long    osc_waveform       '0

    long    osc_state          '0
    
    long    osc_target[4]      '0[4]
    long    osc_vol[4]         '(127<<12)[4]
    
    long    osc_inc[4]         '0[4]
    long    osc_acc[4]         '0[4]    
  
    long    freqtable[12]       '439638, 465780, 493477, 522820, 553909, 586846      ' precalculated frequency constants
                                '621742, 658713, 697882, 739380, 783346, 829926      ' see frequencytiming

PUB null
   
PUB Start
    osc_sample      :=    0

    osc_envelope    :=    $01010101 
    osc_attack      :=    $7F7F7F7F
    osc_decay       :=    0
    osc_sustain     :=    $7F7F7F7F
    osc_release     :=    0
    osc_waveform    :=    0

    osc_state       :=    0
    
    osc_target[0]   :=    0
    osc_target[1]   :=    0
    osc_target[2]   :=    0
    osc_target[3]   :=    0
    
    osc_vol[0]      :=    (127<<12)
    osc_vol[1]      :=    (127<<12)
    osc_vol[2]      :=    (127<<12)
    osc_vol[3]      :=    (127<<12)
    
    osc_inc[0]         :=    0
    osc_inc[1]         :=    0
    osc_inc[2]         :=    0
    osc_inc[3]         :=    0

    osc_acc[0]         :=    0    
    osc_acc[1]         :=    0    
    osc_acc[2]         :=    0    
    osc_acc[3]         :=    0    
  
    freqtable[0]       :=    439638
    freqtable[1]       :=    465780
    freqtable[2]       :=    493477
    freqtable[3]       :=    522820
    freqtable[4]       :=    553909
    freqtable[5]       :=    586846      ' precalculated frequency constants
    freqtable[6]       :=    621742
    freqtable[7]       :=    658713
    freqtable[8]       :=    697882
    freqtable[9]       :=    739380
    freqtable[10]      :=    783346
    freqtable[11]      :=    829926      ' see frequencytiming
    
    cognew(@entry, @osc_sample)    'start assembly cog
    
PUB SetVolume(channel, value)
    
    osc_vol[channel] := value << 12
    
PUB SetNote(channel, value)
    
    osc_inc[channel] := freqtable[value//12] >> (9 - value/12)
    
PUB SetFreq(channel, value)
    
    osc_inc[channel] := value

PUB SetParam(channel, type, value)

    byte[@osc_envelope[type]][channel] := value
    
PUB SetADSR(channel, attackvar, decayvar, sustainvar, releasevar)
    
    osc_attack.byte[channel] := attackvar
    osc_decay.byte[channel] := decayvar
    osc_sustain.byte[channel] := sustainvar
    osc_release.byte[channel] := releasevar
    
PUB LoadPatch(patchAddr) | i, j, t, c

    c := byte[patchAddr] & $F
        
    repeat j from 0 to 3
        if c & $1
            SetEnvelope(j,1)
            t := patchAddr + 1
            repeat i from _ATK to _WAV
                SetParam(j, i, byte[t++])
        c >>= 1
    
PUB SetWaveform(channel, value)
    
    osc_waveform.byte[channel] := value
    
PUB SetEnvelope(channel, value)
   
    osc_envelope.byte[channel] &= constant(!1)
    if value
        osc_envelope.byte[channel] |= 1
    
PUB StartEnvelope(channel, enable)
    osc_envelope.byte[channel] &= constant(!2)
    if enable
        osc_envelope.byte[channel] |= 2
    osc_envelope.byte[channel] |= 4
    osc_envelope.byte[channel] &= !4
 
PUB SetSample(value)
    
    osc_sample := value

PUB PlaySound(channel, value)
    
    SetEnvelope(channel, 1)
    StartEnvelope(channel, 1)
    SetNote(channel, value)

PUB StopSound(channel)
    
    StartEnvelope(channel, 0)
    
PUB StopAllSound | i

    repeat i from 0 to 3
        StopSound(i)
        
DAT
                        org
' ---------------------------------------------------------------
' Setup
' ---------------------------------------------------------------
entry                  '{
                        mov      addr, par
                        add      addr, #144
                        rdlong   ctraval, addr
                        add      addr, #4
                        rdlong   diraval, addr
                        add      addr, #4

Rayman · 2020-10-27 23:21

I'd guess changing the value of "Period" would do it...

change speed of WAV playback?

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