Module: WSK::FFT

Included in:
Actions::CutFirstSignal, Actions::FFT, Actions::NoiseGate, Actions::SilenceRemover
Defined in:
lib/WSK/FFT.rb

Overview

Module including helper methods using FFT processes. This module uses C methods declared in FFTUtils.

Defined Under Namespace

Classes: FFTComputing

Constant Summary collapse

FREQINDEX_FIRST =

Frequencies used to compute FFT profiles. !!! When changing these values, all fft.result files generated are invalidated

-59
FREQINDEX_LAST = 
79
FFTDIST_MAX =

Scale used to measure FFT values

10000000000000
FFTSAMPLE_FREQ =

Frequency of the FFT samples to take (Hz) !!! If changed, all fft.result files generated are invalidated

10
FFTNBRSAMPLES_HISTORY =

Number of FFT buffers needed to detect a constant Moving Average. !!! If changed, all fft.result files generated are invalidated

5
FFT_SAMPLES_PREFETCH =

Number of samples to prefetch from the disk when reading. This should reflect the average number of FFT samples read when getNextFFTSample is invoked once. !!! If changed, all fft.result files generated are invalidated

30
FFTDISTANCE_MAX_HISTORY_TOLERANCE_PC =

Added tolerance percentage of distance between the maximal history distance and the average silence distance

20.0
FFTDISTANCE_AVERAGE_HISTORY_TOLERANCE_PC =

Added tolerance percentage of distance between the average history distance and the average silence distance

0.0

Instance Method Summary collapse

Instance Method Details

#getNextFFTSample(iIdxFirstSample, iFFTProfile, iInputData, iMaxFFTDistance, iThresholds, iBackwardsSearch, iIdxLastPossibleSample) ⇒ Object

Get the next sample that has an FFT buffer similar to a given FFT profile

Parameters

  • iIdxFirstSample (Integer): First sample we are trying from

  • iFFTProfile ([Integer,Integer,list<list<Integer>>]): The FFT profile

  • iInputData (InputData): The input data to read

  • iMaxFFTDistance (Integer): Maximal acceptable distance with the FFT. Above this distance we don’t consider averaging.

  • iThresholds (list< [Integer,Integer] >): The thresholds that should contain the signal we are evaluating.

  • iBackwardsSearch (Boolean): Do we search backwards ?

  • iIdxLastPossibleSample (Integer): Index of the sample marking the limit of the search

Return

  • Integer: Meaning of the given sample:

    • 0: The sample has been found correctly and returned

    • 1: The sample could not be found because thresholds were hit: the first sample hitting the thresholds is returned

    • 2: The sample could not be found because the limit of search was hit before. The returned sample can be ignored.

  • Integer: Index of the sample (can be 1 after the end)



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# File 'lib/WSK/FFT.rb', line 148

def getNextFFTSample(iIdxFirstSample, iFFTProfile, iInputData, iMaxFFTDistance, iThresholds, iBackwardsSearch, iIdxLastPossibleSample)
  rResultCode = 0
  rCurrentSample = iIdxFirstSample

  if (iBackwardsSearch)
    log_debug "== Looking for the previous sample matching FFT before #{iIdxFirstSample}, with a limit on sample #{iIdxLastPossibleSample} and a FFT distance of #{iMaxFFTDistance} ..."
  else
    log_debug "== Looking for the next sample matching FFT after #{iIdxFirstSample}, with a limit on sample #{iIdxLastPossibleSample} and a FFT distance of #{iMaxFFTDistance} ..."
  end

  # Object that will create the FFT
  lFFTComputing = FFTComputing.new(true, iInputData.Header)
  # Create the C FFT Profile
  lFFTUtils = FFTUtils::FFTUtils.new
  lReferenceFFTProfile = lFFTUtils.createCFFTProfile(iFFTProfile)
  # Historical values of FFT diffs to know when it is stable
  # This is the implementation of the Moving Average algorithm.
  # We are just interested in the difference of 2 different Moving Averages. Therefore comparing the oldest history value with the new one is enough.
  # Cycling buffer of size FFTNBRSAMPLES_HISTORY
  # list< Integer >
  lHistory = []
  lIdxOldestHistory = 0
  # The sum of all the history entries: used to compare with the maximal average distance
  lSumHistory = 0
  lSumMaxFFTDistance = (iMaxFFTDistance*FFTNBRSAMPLES_HISTORY*(1+FFTDISTANCE_AVERAGE_HISTORY_TOLERANCE_PC/100)).to_i
  lMaxHistoryFFTDistance = (iMaxFFTDistance*(1+FFTDISTANCE_MAX_HISTORY_TOLERANCE_PC/100)).to_i
  lContinueSearching = nil
  if (iBackwardsSearch)
    lContinueSearching = (rCurrentSample >= iIdxLastPossibleSample)
  else
    lContinueSearching = (rCurrentSample <= iIdxLastPossibleSample)
  end
  while (lContinueSearching)
    # Compute the number of samples needed to have a valid FFT.
    # Modify this number if it exceeds the range we have
    lNbrSamplesFFTMax = iInputData.Header.SampleRate/FFTSAMPLE_FREQ
    lIdxBeginFFTSample = nil
    lIdxEndFFTSample = nil
    if (iBackwardsSearch)
      lIdxBeginFFTSample = rCurrentSample-lNbrSamplesFFTMax+1
      lIdxEndFFTSample = rCurrentSample
      if (lIdxBeginFFTSample <= iIdxLastPossibleSample-1)
        lIdxBeginFFTSample = iIdxLastPossibleSample
      end
    else
      lIdxBeginFFTSample = rCurrentSample
      lIdxEndFFTSample = rCurrentSample+lNbrSamplesFFTMax-1
      if (lIdxEndFFTSample >= iIdxLastPossibleSample+1)
        lIdxEndFFTSample = iIdxLastPossibleSample
      end
    end
    lNbrSamplesFFT = lIdxEndFFTSample-lIdxBeginFFTSample+1
    # Load an FFT buffer of this
    lFFTBuffer = ''
    lIdxCurrentSample = rCurrentSample
    if (iBackwardsSearch)
      iInputData.each_reverse_raw_buffer(lIdxBeginFFTSample, lIdxEndFFTSample, :nbr_samples_prefetch => lNbrSamplesFFTMax*FFT_SAMPLES_PREFETCH ) do |iInputRawBuffer, iNbrSamples, iNbrChannels|
        # First, check that we are still in the thresholds
        lIdxBufferSampleOut = getSampleBeyondThresholds(iInputRawBuffer, iThresholds, iInputData.Header.NbrBitsPerSample, iNbrChannels, iNbrSamples, iBackwardsSearch)
        if (lIdxBufferSampleOut != nil)
          # Cancel this FFT search: the signal is out of the thresholds
          rCurrentSample = lIdxCurrentSample-iNbrSamples+1+lIdxBufferSampleOut
          rResultCode = 1
          break
        end
        lFFTBuffer.insert(0, iInputRawBuffer)
        lIdxCurrentSample -= iNbrSamples
      end
    else
      iInputData.each_raw_buffer(lIdxBeginFFTSample, lIdxEndFFTSample, :nbr_samples_prefetch => lNbrSamplesFFTMax*FFT_SAMPLES_PREFETCH) do |iInputRawBuffer, iNbrSamples, iNbrChannels|
        # First, check that we are still in the thresholds
        lIdxBufferSampleOut = getSampleBeyondThresholds(iInputRawBuffer, iThresholds, iInputData.Header.NbrBitsPerSample, iNbrChannels, iNbrSamples, iBackwardsSearch)
        if (lIdxBufferSampleOut != nil)
          # Cancel this FFT search: the signal is out of the thresholds
          rCurrentSample = lIdxCurrentSample+lIdxBufferSampleOut
          rResultCode = 1
          break
        end
        lFFTBuffer.concat(iInputRawBuffer)
        lIdxCurrentSample += iNbrSamples
      end
    end
    if (rResultCode == 1)
      lContinueSearching = false
    else
      # Compute its FFT profile
      lFFTComputing.resetData
      lFFTComputing.completeFFT(lFFTBuffer, lNbrSamplesFFT)
      lDist = lFFTUtils.distFFTProfiles(lReferenceFFTProfile, lFFTUtils.createCFFTProfile(lFFTComputing.getFFTProfile), FFTDIST_MAX).abs
      lHistoryMaxDistance = lHistory.sort[-1]
      log_debug "FFT distance computed with FFT sample [#{lIdxBeginFFTSample} - #{lIdxEndFFTSample}]: #{lDist}. Sum of history: #{lSumHistory} <? #{lSumMaxFFTDistance}. Max distance of history: #{lHistoryMaxDistance} <? #{lMaxHistoryFFTDistance}"
      # Detect if the Moving Average is going up and is below the maximal distance
      if ((lHistory.size == FFTNBRSAMPLES_HISTORY) and
          (lSumHistory < lSumMaxFFTDistance) and
          (lHistoryMaxDistance < lMaxHistoryFFTDistance) and
          (lHistory[lIdxOldestHistory] < lDist))
        # We got it
        lContinueSearching = false
      else
        # Check next FFT sample
        if (iBackwardsSearch)
          rCurrentSample = lIdxBeginFFTSample - 1
          lContinueSearching = (rCurrentSample >= iIdxLastPossibleSample)
        else
          rCurrentSample = lIdxEndFFTSample + 1
          lContinueSearching = (rCurrentSample <= iIdxLastPossibleSample)
        end
        if (lContinueSearching)
          # Update the history with the new diff
          if (lHistory[lIdxOldestHistory] == nil)
            lSumHistory += lDist
          else
            lSumHistory += lDist - lHistory[lIdxOldestHistory]
          end
          lHistory[lIdxOldestHistory] = lDist
          lIdxOldestHistory += 1
          if (lIdxOldestHistory == FFTNBRSAMPLES_HISTORY)
            lIdxOldestHistory = 0
          end
        end
      end
    end
  end
  if ((rResultCode == 0) and
      (((iBackwardsSearch) and
        (rCurrentSample == iIdxLastPossibleSample-1)) or
       ((!iBackwardsSearch) and
        (rCurrentSample == iIdxLastPossibleSample+1))))
    # Limit was hit
    rResultCode = 2
  end

  case rResultCode
  when 0
    if (iBackwardsSearch)
      log_debug "== Previous sample matching FFT before #{iIdxFirstSample} was found at #{rCurrentSample}."
    else
      log_debug "== Next sample matching FFT after #{iIdxFirstSample} was found at #{rCurrentSample}."
    end
  when 1
    if (iBackwardsSearch)
      log_debug "== Previous sample matching FFT before #{iIdxFirstSample} could not be found because a sample exceeded thresholds meanwhile: #{rCurrentSample}."
    else
      log_debug "== Next sample matching FFT after #{iIdxFirstSample} could not be found because a sample exceeded thresholds meanwhile: #{rCurrentSample}."
    end
  when 2
    if (iBackwardsSearch)
      log_debug "== Previous sample matching FFT before #{iIdxFirstSample} could not be found before hitting limit of #{iIdxLastPossibleSample}."
    else
      log_debug "== Next sample matching FFT after #{iIdxFirstSample} could not be found before hitting limit of #{iIdxLastPossibleSample}."
    end
  else
    log_err "Unknown result code: #{rResultCode}"
  end

  return rResultCode, rCurrentSample
end

#getNextNonSilentSample(iInputData, iIdxStartSample, iSilenceThresholds, iSilenceFFTProfile, iMaxFFTDistance, iBackwardsSearch) ⇒ Object

Get the next non silent sample from an input data

Parameters

  • iInputData (WSK::Model::InputData): The input data

  • iIdxStartSample (Integer): Index of the first sample to search from

  • iSilenceThresholds (list< [Integer,Integer] >): The silence thresholds specifications

  • iSilenceFFTProfile ([Integer,Integer,list<list<Integer>>]): The silence FFT profile, or nil if none

  • iMaxFFTDistance (Integer): Max distance to consider with the FFT (ignored and can be nil if no FFT).

  • iBackwardsSearch (Boolean): Do we search backwards ?

Return

  • Integer: Index of the next non silent sample, or nil if none

  • Integer: Index of the next sample getting above thresholds, or nil if none



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# File 'lib/WSK/FFT.rb', line 432

def getNextNonSilentSample(iInputData, iIdxStartSample, iSilenceThresholds, iSilenceFFTProfile, iMaxFFTDistance, iBackwardsSearch)
  rIdxSampleOut = nil
  rIdxSampleOutThresholds = nil
  
  if (iBackwardsSearch)
    log_debug "=== Looking for the previous signal sample before #{iIdxStartSample} ..."
  else
    log_debug "=== Looking for the next signal sample after #{iIdxStartSample} ..."
  end

  # Find the next sample getting out of the silence thresholds
  lIdxCurrentSample = iIdxStartSample
  if (iBackwardsSearch)
    iInputData.each_reverse_raw_buffer(0, iIdxStartSample) do |iInputRawBuffer, iNbrSamples, iNbrChannels|
      lIdxBufferSampleOut = getSampleBeyondThresholds(iInputRawBuffer, iSilenceThresholds, iInputData.Header.NbrBitsPerSample, iNbrChannels, iNbrSamples, iBackwardsSearch)
      if (lIdxBufferSampleOut != nil)
        # We found it
        rIdxSampleOutThresholds = lIdxCurrentSample-iNbrSamples+1+lIdxBufferSampleOut
        break
      end
      lIdxCurrentSample -= iNbrSamples
    end
  else
    iInputData.each_raw_buffer(iIdxStartSample) do |iInputRawBuffer, iNbrSamples, iNbrChannels|
      lIdxBufferSampleOut = getSampleBeyondThresholds(iInputRawBuffer, iSilenceThresholds, iInputData.Header.NbrBitsPerSample, iNbrChannels, iNbrSamples, iBackwardsSearch)
      if (lIdxBufferSampleOut != nil)
        # We found it
        rIdxSampleOutThresholds = lIdxCurrentSample+lIdxBufferSampleOut
        break
      end
      lIdxCurrentSample += iNbrSamples
    end
  end
  if (rIdxSampleOutThresholds == nil)
    log_debug("Thresholds matching did not find any signal starting at sample #{iIdxStartSample}.")
  else
    log_debug("Thresholds matching found a signal starting at sample #{iIdxStartSample}, beginning at sample #{rIdxSampleOutThresholds}.")
    # If we want to use FFT to have a better result, do it here
    if (iSilenceFFTProfile == nil)
      rIdxSampleOut = rIdxSampleOutThresholds
    else
      # Check FFT
      # We search in the reverse direction to find the silence, knowing that we can't have a sample getting past our initial search sample
      lFFTResultCode = nil
      lIdxFFTSample = nil
      if (iBackwardsSearch)
        lFFTResultCode, lIdxFFTSample = getNextFFTSample(rIdxSampleOutThresholds+1, iSilenceFFTProfile, iInputData, iMaxFFTDistance, iSilenceThresholds, false, iIdxStartSample)
      else
        lFFTResultCode, lIdxFFTSample = getNextFFTSample(rIdxSampleOutThresholds-1, iSilenceFFTProfile, iInputData, iMaxFFTDistance, iSilenceThresholds, true, iIdxStartSample)
      end
      case lFFTResultCode
      when 0
        # We found the real one
        log_debug("FFT matching found a silence starting at sample #{rIdxSampleOutThresholds}, beginning at sample #{lIdxFFTSample}.")
        rIdxSampleOut = lIdxFFTSample
      when 1
        # Here is a bug
        log_err("FFT matching found a new signal beyond thresholds starting at sample #{rIdxSampleOutThresholds}, beginning at sample #{lIdxFFTSample}. This should never happen here: the previous search using thresholds should have already returned this sample.")
        raise RuntimeError.new("FFT matching found a new signal beyond thresholds starting at sample #{rIdxSampleOutThresholds}, beginning at sample #{lIdxFFTSample}. This should never happen here: the previous search using thresholds should have already returned this sample.")
      when 2
        log_debug("FFT matching could not find a silence starting at sample #{rIdxSampleOutThresholds}. This means that the signal is present from the start.")
        rIdxSampleOut = iIdxStartSample
      else
        raise RuntimeError.new("Unknown result code: #{lFFTResultCode}")
      end
    end
  end

  if (iBackwardsSearch)
    log_debug "=== Previous signal sample before #{iIdxStartSample} was found at #{rIdxSampleOut}, with a sample beyond thresholds at #{rIdxSampleOutThresholds}."
  else
    log_debug "=== Next signal sample after #{iIdxStartSample} was found at #{rIdxSampleOut}, with a sample beyond thresholds at #{rIdxSampleOutThresholds}."
  end

  return rIdxSampleOut, rIdxSampleOutThresholds
end

#getNextSilentSample(iInputData, iIdxStartSample, iSilenceThresholds, iMinSilenceSamples, iSilenceFFTProfile, iMaxFFTDistance, iBackwardsSearch) ⇒ Object

Get the next silent sample from an input data

Parameters

  • iInputData (WSK::Model::InputData): The input data

  • iIdxStartSample (Integer): Index of the first sample to search from

  • iSilenceThresholds (list< [Integer,Integer] >): The silence thresholds specifications

  • iMinSilenceSamples (Integer): Number of samples minimum to identify a silence

  • iSilenceFFTProfile ([Integer,Integer,list<list<Integer>>]): The silence FFT profile, or nil if none

  • iMaxFFTDistance (Integer): Max distance to consider with the FFT (ignored and can be nil if no FFT).

  • iBackwardsSearch (Boolean): Do we make a backwards search ?

Return

  • Integer: Index of the next silent sample, or nil if none

  • Integer: Silence length (computed only if FFT profile was provided)

  • Integer: Index of the next sample after the silence that is beyond thresholds (computed only if FFT profile was provided)



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# File 'lib/WSK/FFT.rb', line 320

def getNextSilentSample(iInputData, iIdxStartSample, iSilenceThresholds, iMinSilenceSamples, iSilenceFFTProfile, iMaxFFTDistance, iBackwardsSearch)
  rNextSilentSample = nil
  rSilenceLength = nil
  rNextSignalAboveThresholds = nil

  if (iBackwardsSearch)
    log_debug "=== Looking for the previous silent sample before #{iIdxStartSample}, of minimal length #{iMinSilenceSamples} ..."
  else
    log_debug "=== Looking for the next silent sample after #{iIdxStartSample}, of minimal length #{iMinSilenceSamples} ..."
  end
  
  lIdxSearchSample = iIdxStartSample
  lContinueSearching = true
  while (lContinueSearching)
    # We search starting at lIdxSearchSample
    lContinueSearching = false
    # First find using thresholds only
    require 'WSK/SilentUtils/SilentUtils'
    rNextSilentSample = SilentUtils::SilentUtils.new.getNextSilentInThresholds(iInputData, lIdxSearchSample, iSilenceThresholds, iMinSilenceSamples, iBackwardsSearch)
    if (rNextSilentSample == nil)
      log_debug("Thresholds matching did not find any silence starting at sample #{iIdxStartSample}.")
    else
      log_debug("Thresholds matching found a silence starting at sample #{iIdxStartSample}, beginning at sample #{rNextSilentSample}.")
      # If we want to use FFT to have a better result, do it here
      if (iSilenceFFTProfile != nil)
        # Check FFT
        if (iBackwardsSearch)
          lFFTResultCode, lIdxFFTSample = getNextFFTSample(rNextSilentSample, iSilenceFFTProfile, iInputData, iMaxFFTDistance, iSilenceThresholds, iBackwardsSearch, 0)
        else
          lFFTResultCode, lIdxFFTSample = getNextFFTSample(rNextSilentSample, iSilenceFFTProfile, iInputData, iMaxFFTDistance, iSilenceThresholds, iBackwardsSearch, iInputData.NbrSamples-1)
        end
        case lFFTResultCode
        when 0
          # Check that the silence lasts at least iMinSilenceSamples
          lIdxNextSignal = nil
          lIdxNextSignalAboveThresholds = nil
          lSilenceLength = nil
          if (iBackwardsSearch)
            lIdxNextSignal, lIdxNextSignalAboveThresholds = getNextNonSilentSample(iInputData, lIdxFFTSample-1, iSilenceThresholds, iSilenceFFTProfile, iMaxFFTDistance, iBackwardsSearch)
            if (lIdxNextSignal == nil)
              # No signal was found further.
              lSilenceLength = lIdxFFTSample
            else
              lSilenceLength = lIdxFFTSample - lIdxNextSignal - 1
            end
          else
            lIdxNextSignal, lIdxNextSignalAboveThresholds = getNextNonSilentSample(iInputData, lIdxFFTSample+1, iSilenceThresholds, iSilenceFFTProfile, iMaxFFTDistance, iBackwardsSearch)
            if (lIdxNextSignal == nil)
              # No signal was found further.
              lSilenceLength = iInputData.NbrSamples - 1 - lIdxFFTSample
            else
              lSilenceLength = lIdxNextSignal - 1 - lIdxFFTSample
            end
          end
          if (lSilenceLength >= iMinSilenceSamples)
            # We found the real one
            log_debug("FFT matching found a silence starting at sample #{rNextSilentSample}, beginning at sample #{lIdxFFTSample}.")
            rNextSilentSample = lIdxFFTSample
            rSilenceLength = lSilenceLength
            rNextSignalAboveThresholds = lIdxNextSignalAboveThresholds
          elsif (lIdxNextSignal == nil)
            # We arrived at the end. The silence is not long enough.
            log_debug("FFT matching found a silence starting at sample #{rNextSilentSample}, beginning at sample #{lIdxFFTSample}, but its length (#{lSilenceLength}) is too small (minimum required is #{iMinSilenceSamples}). End of file reached.")
            rNextSilentSample = nil
          else
            # We have to continue
            log_debug("FFT matching found a silence starting at sample #{rNextSilentSample}, beginning at sample #{lIdxFFTSample}, but its length (#{lSilenceLength}) is too small (minimum required is #{iMinSilenceSamples}). Looking further.")
            lIdxSearchSample = lIdxNextSignalAboveThresholds
            lContinueSearching = true
            rNextSilentSample = nil
          end
        when 1
          # We have to search further, begin with thresholds matching
          log_warn("FFT matching found a new signal beyond thresholds starting at sample #{rNextSilentSample}, beginning at sample #{lIdxFFTSample}. Maybe clip ?")
          if (iBackwardsSearch)
            lIdxSearchSample = lIdxFFTSample - 1
          else
            lIdxSearchSample = lIdxFFTSample + 1
          end
          lContinueSearching = true
          rNextSilentSample = nil
        when 2
          log_debug("FFT matching could not find a silence starting at sample #{rNextSilentSample}.")
          rNextSilentSample = nil
        else
          raise RuntimeError.new("Unknown result code: #{lFFTResultCode}")
        end
      end
    end
  end

  if (iBackwardsSearch)
    log_debug "=== Previous silent sample before #{iIdxStartSample} was found at #{rNextSilentSample} with a length of #{rSilenceLength}, and a signal before it above thresholds at #{rNextSignalAboveThresholds}."
  else
    log_debug "=== Next silent sample after #{iIdxStartSample} was found at #{rNextSilentSample} with a length of #{rSilenceLength}, and an signal after it above thresholds at #{rNextSignalAboveThresholds}."
  end

  return rNextSilentSample, rSilenceLength, rNextSignalAboveThresholds
end

#getSampleBeyondThresholds(iRawBuffer, iThresholds, iNbrBitsPerSample, iNbrChannels, iNbrSamples, iLastSample) ⇒ Object

Get the sample index that exceeds a threshold in a raw buffer.

Parameters

  • iRawBuffer (String): The raw buffer

  • iThresholds (list< [Integer,Integer] >): The thresholds

  • iNbrBitsPerSample (Integer): Number of bits per sample

  • iNbrChannels (Integer): Number of channels

  • iNbrSamples (Integer): Number of samples

  • iLastSample (Boolean): Are we looking for the last sample ?

Return

  • Integer: Index of the first sample exceeding thresholds, or nil if none



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# File 'lib/WSK/FFT.rb', line 520

def getSampleBeyondThresholds(iRawBuffer, iThresholds, iNbrBitsPerSample, iNbrChannels, iNbrSamples, iLastSample)
  require 'WSK/SilentUtils/SilentUtils'
  return SilentUtils::SilentUtils.new.getSampleBeyondThresholds(iRawBuffer, iThresholds, iNbrBitsPerSample, iNbrChannels, iNbrSamples, iLastSample)
end