8

I have noticed in some YouTube videos that pauses in speech have been cut out. There are no pauses, and this makes the video easier to watch.

How is this done? I have searched for this, but have only found tutorials on doing this manually, but there must be an automatic way for YouTube videos, I hope!

Here's an example of one of these videos:

  • 2
    I've been making YouTube videos since 2006, and I cut out the pauses in my videos. I've never heard of an automatic way to do it! However, your video editing software (like iMovie or Premiere) may show the audio track as a visible sound wave on screen. I look for the points when it's "silent", and cut those out. Yes, it's a manual process, but it's easier and quicker to look at the sound wave in the audio track than to listen for the start and ending of everything I said in the video. – BrettFromLA Oct 16 '15 at 19:02
  • I also do not know of an automatic way to do this. Keep in mind that any automatic method, if it exists, won't be able to distinguish a pause mid-clause from a pause between, say, two sentences. So, you'll have to scan the result manually, which defeats the purpose. – Gyan Oct 17 '15 at 5:22
  • @BrettFromLA There is a way, I read about it before, just can't remember the program. – user11867 Oct 18 '15 at 13:39
  • I have this same question, and it's related to these 2 others: superuser.com/questions/990357/… – Ryan Jun 22 '18 at 11:45
5

The effect you are talking about is called jumpcut and it is particularly popular among vloggers.
As far as I know, there is no automatic way to do it although it would probably be possible to do from technological perspective. However using jumpcuts has several functions.

You get rid of silence and squeeze as much information in short form as possible, keeping viewers attention.
Second important function is selection of your shots. While going through your material (shot usually in one take) you can discard stuff you don't want (even if you were talking at that point) and fundamentally alter the tone of your video.

This increased creative control is worth it considering that editing your video manually in this manner is very easy and won't take much time or effort.


tl;dr
It might be doable, but there is no user friendly solution now. Anyway I would suggest to do it manually for various reasons described in full answer.

4

You are missing the point. He is not cutting out silence, he is keeping up a good hectic pace, making it hard to switch off while watching.

Manually done. Why?

  • Telling a story, so you need to know what parts are relevant and what parts aren't

  • Sometimes even though there are silent parts, there are other visual things going on, like wild gestures, funny faces, a pause for dramatic effect.

  • Sometimes your cuts are NOT chronological in order. To make a story better you might pick clips or add clips from a completely different timeline or video.

The main issue you will find is the 'clicks' you here when you make the jump cuts. Normally you unlink the audio and video and you ONLY transition the audio part.

Hope that helps. Happy clipping.

2

On Avid ProTools when you are working on a video with an audio track, there are some hotkeys to automatically select all the audio parts where the waveform goes to zero or near to it.

Extending the selection also to the video track and cutting it off as well should do the trick, then you have just to use another hotkey to join the cutted pieces together without pauses in the middle.

I think this workflow could be applied on almost all the NLE (non linear editors) available around.

1

You can use Laconia Trim for iOS or LaconiaTrimVideo.com for online trimming

Both trims silence in video automatically.

1

When you delete silence (time to breathe, respond, awkward pause), for every hour of show, is 10-minutes of dead air. The sound of nothing.

Attention is already hard...you speak at 120 WPM. Your brain can handle 400. In the empty space is where your brain gets distracted.

I use desktop software for MAC or PC to automatically remove dead air / silence from MP4 & MP3 Files. Look at a graph, set audio level and split-time, hit run. The cuts are automated, and recompiled back into a single MP4 or MP3 file. See TimeBolt.io

enter image description here

Disclaimer I own this tool.

  • Interesting product, congratulations. – Rafael Oct 15 at 6:34
  • Thank you @Rafael – Doug Wulff Oct 24 at 13:31
0

https://github.com/carykh/jumpcutter (MIT license) automatically removes parts of a video that have no or little audio. It relies on ffmpeg and the pipeline is coded in Python 3.

Explanation:

Script (MIT license, author: carykh):

from contextlib import closing
from PIL import Image
import subprocess
from audiotsm import phasevocoder
from audiotsm.io.wav import WavReader, WavWriter
from scipy.io import wavfile
import numpy as np
import re
import math
from shutil import copyfile, rmtree
import os
import argparse
from pytube import YouTube

def downloadFile(url):
    name = YouTube(url).streams.first().download()
    newname = name.replace(' ','_')
    os.rename(name,newname)
    return newname

def getMaxVolume(s):
    maxv = float(np.max(s))
    minv = float(np.min(s))
    return max(maxv,-minv)

def copyFrame(inputFrame,outputFrame):
    src = TEMP_FOLDER+"/frame{:06d}".format(inputFrame+1)+".jpg"
    dst = TEMP_FOLDER+"/newFrame{:06d}".format(outputFrame+1)+".jpg"
    if not os.path.isfile(src):
        return False
    copyfile(src, dst)
    if outputFrame%20 == 19:
        print(str(outputFrame+1)+" time-altered frames saved.")
    return True

def inputToOutputFilename(filename):
    dotIndex = filename.rfind(".")
    return filename[:dotIndex]+"_ALTERED"+filename[dotIndex:]

def createPath(s):
    #assert (not os.path.exists(s)), "The filepath "+s+" already exists. Don't want to overwrite it. Aborting."

    try:  
        os.mkdir(s)
    except OSError:  
        assert False, "Creation of the directory %s failed. (The TEMP folder may already exist. Delete or rename it, and try again.)"

def deletePath(s): # Dangerous! Watch out!
    try:  
        rmtree(s,ignore_errors=False)
    except OSError:  
        print ("Deletion of the directory %s failed" % s)
        print(OSError)

parser = argparse.ArgumentParser(description='Modifies a video file to play at different speeds when there is sound vs. silence.')
parser.add_argument('--input_file', type=str,  help='the video file you want modified')
parser.add_argument('--url', type=str, help='A youtube url to download and process')
parser.add_argument('--output_file', type=str, default="", help="the output file. (optional. if not included, it'll just modify the input file name)")
parser.add_argument('--silent_threshold', type=float, default=0.03, help="the volume amount that frames' audio needs to surpass to be consider \"sounded\". It ranges from 0 (silence) to 1 (max volume)")
parser.add_argument('--sounded_speed', type=float, default=1.00, help="the speed that sounded (spoken) frames should be played at. Typically 1.")
parser.add_argument('--silent_speed', type=float, default=5.00, help="the speed that silent frames should be played at. 999999 for jumpcutting.")
parser.add_argument('--frame_margin', type=float, default=1, help="some silent frames adjacent to sounded frames are included to provide context. How many frames on either the side of speech should be included? That's this variable.")
parser.add_argument('--sample_rate', type=float, default=44100, help="sample rate of the input and output videos")
parser.add_argument('--frame_rate', type=float, default=30, help="frame rate of the input and output videos. optional... I try to find it out myself, but it doesn't always work.")
parser.add_argument('--frame_quality', type=int, default=3, help="quality of frames to be extracted from input video. 1 is highest, 31 is lowest, 3 is the default.")

args = parser.parse_args()



frameRate = args.frame_rate
SAMPLE_RATE = args.sample_rate
SILENT_THRESHOLD = args.silent_threshold
FRAME_SPREADAGE = args.frame_margin
NEW_SPEED = [args.silent_speed, args.sounded_speed]
if args.url != None:
    INPUT_FILE = downloadFile(args.url)
else:
    INPUT_FILE = args.input_file
URL = args.url
FRAME_QUALITY = args.frame_quality

assert INPUT_FILE != None , "why u put no input file, that dum"

if len(args.output_file) >= 1:
    OUTPUT_FILE = args.output_file
else:
    OUTPUT_FILE = inputToOutputFilename(INPUT_FILE)

TEMP_FOLDER = "TEMP"
AUDIO_FADE_ENVELOPE_SIZE = 400 # smooth out transitiion's audio by quickly fading in/out (arbitrary magic number whatever)

createPath(TEMP_FOLDER)

command = "ffmpeg -i "+INPUT_FILE+" -qscale:v "+str(FRAME_QUALITY)+" "+TEMP_FOLDER+"/frame%06d.jpg -hide_banner"
subprocess.call(command, shell=True)

command = "ffmpeg -i "+INPUT_FILE+" -ab 160k -ac 2 -ar "+str(SAMPLE_RATE)+" -vn "+TEMP_FOLDER+"/audio.wav"

subprocess.call(command, shell=True)

command = "ffmpeg -i "+TEMP_FOLDER+"/input.mp4 2>&1"
f = open(TEMP_FOLDER+"/params.txt", "w")
subprocess.call(command, shell=True, stdout=f)



sampleRate, audioData = wavfile.read(TEMP_FOLDER+"/audio.wav")
audioSampleCount = audioData.shape[0]
maxAudioVolume = getMaxVolume(audioData)

f = open(TEMP_FOLDER+"/params.txt", 'r+')
pre_params = f.read()
f.close()
params = pre_params.split('\n')
for line in params:
    m = re.search('Stream #.*Video.* ([0-9]*) fps',line)
    if m is not None:
        frameRate = float(m.group(1))

samplesPerFrame = sampleRate/frameRate

audioFrameCount = int(math.ceil(audioSampleCount/samplesPerFrame))

hasLoudAudio = np.zeros((audioFrameCount))



for i in range(audioFrameCount):
    start = int(i*samplesPerFrame)
    end = min(int((i+1)*samplesPerFrame),audioSampleCount)
    audiochunks = audioData[start:end]
    maxchunksVolume = float(getMaxVolume(audiochunks))/maxAudioVolume
    if maxchunksVolume >= SILENT_THRESHOLD:
        hasLoudAudio[i] = 1

chunks = [[0,0,0]]
shouldIncludeFrame = np.zeros((audioFrameCount))
for i in range(audioFrameCount):
    start = int(max(0,i-FRAME_SPREADAGE))
    end = int(min(audioFrameCount,i+1+FRAME_SPREADAGE))
    shouldIncludeFrame[i] = np.max(hasLoudAudio[start:end])
    if (i >= 1 and shouldIncludeFrame[i] != shouldIncludeFrame[i-1]): # Did we flip?
        chunks.append([chunks[-1][1],i,shouldIncludeFrame[i-1]])

chunks.append([chunks[-1][1],audioFrameCount,shouldIncludeFrame[i-1]])
chunks = chunks[1:]

outputAudioData = np.zeros((0,audioData.shape[1]))
outputPointer = 0

lastExistingFrame = None
for chunk in chunks:
    audioChunk = audioData[int(chunk[0]*samplesPerFrame):int(chunk[1]*samplesPerFrame)]

    sFile = TEMP_FOLDER+"/tempStart.wav"
    eFile = TEMP_FOLDER+"/tempEnd.wav"
    wavfile.write(sFile,SAMPLE_RATE,audioChunk)
    with WavReader(sFile) as reader:
        with WavWriter(eFile, reader.channels, reader.samplerate) as writer:
            tsm = phasevocoder(reader.channels, speed=NEW_SPEED[int(chunk[2])])
            tsm.run(reader, writer)
    _, alteredAudioData = wavfile.read(eFile)
    leng = alteredAudioData.shape[0]
    endPointer = outputPointer+leng
    outputAudioData = np.concatenate((outputAudioData,alteredAudioData/maxAudioVolume))

    #outputAudioData[outputPointer:endPointer] = alteredAudioData/maxAudioVolume

    # smooth out transitiion's audio by quickly fading in/out

    if leng < AUDIO_FADE_ENVELOPE_SIZE:
        outputAudioData[outputPointer:endPointer] = 0 # audio is less than 0.01 sec, let's just remove it.
    else:
        premask = np.arange(AUDIO_FADE_ENVELOPE_SIZE)/AUDIO_FADE_ENVELOPE_SIZE
        mask = np.repeat(premask[:, np.newaxis],2,axis=1) # make the fade-envelope mask stereo
        outputAudioData[outputPointer:outputPointer+AUDIO_FADE_ENVELOPE_SIZE] *= mask
        outputAudioData[endPointer-AUDIO_FADE_ENVELOPE_SIZE:endPointer] *= 1-mask

    startOutputFrame = int(math.ceil(outputPointer/samplesPerFrame))
    endOutputFrame = int(math.ceil(endPointer/samplesPerFrame))
    for outputFrame in range(startOutputFrame, endOutputFrame):
        inputFrame = int(chunk[0]+NEW_SPEED[int(chunk[2])]*(outputFrame-startOutputFrame))
        didItWork = copyFrame(inputFrame,outputFrame)
        if didItWork:
            lastExistingFrame = inputFrame
        else:
            copyFrame(lastExistingFrame,outputFrame)

    outputPointer = endPointer

wavfile.write(TEMP_FOLDER+"/audioNew.wav",SAMPLE_RATE,outputAudioData)

'''
outputFrame = math.ceil(outputPointer/samplesPerFrame)
for endGap in range(outputFrame,audioFrameCount):
    copyFrame(int(audioSampleCount/samplesPerFrame)-1,endGap)
'''

command = "ffmpeg -framerate "+str(frameRate)+" -i "+TEMP_FOLDER+"/newFrame%06d.jpg -i "+TEMP_FOLDER+"/audioNew.wav -strict -2 "+OUTPUT_FILE
subprocess.call(command, shell=True)

deletePath(TEMP_FOLDER)
0

You can use the Awkward Pause user script for Adobe After Effects. Cost of the user script: 59.99 USD

Screenshot:

enter image description here

Demo:

Disclaimer: at the time I am writing this post (2019-06-08), I work for Adobe.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy