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I have video tutorials that I am producing using Camtasia using the following process:

  1. Write Script.
  2. Record a voice over.
  3. Record screen while listening the voice over steps.
  4. merge sound and screen recording.

My recordings are little a bit slow and boring and I would like to speed them up like YouTube speed 1.25X, but whenever I speed them up my voice tone changes badly (get more thinner) unlike YouTube Playback, the voice flows at higher rate and voice tone is normal.

How Can I speed them up without affecting my voice tone?

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  • Have you considered using ffmpeg to split the audio and video tracks? By processing only the video, the audio will remain unchanged. Of course your audio will be out of sync with the new shorter duration video track, Whether this is a problem largely depends on the length of the content and might be resolved by selectively removing silence from the audio track. Sorry, I'm not familiar with Camtasia. I hope this helps. – Elder Geek Mar 8 '17 at 15:06
  • @ElderGeek This feature is available in Camtasia, but as you said the audio will be out of sync especially when we are talking about 3 to 5 minutes videos. and it's hard to remove silence. – Mahdi Alkhatib Mar 8 '17 at 18:14
  • On a voice over? over 3 to 5 minutes? I guess I imagined a narration where the voice isn't synced to the imagery. You'd only need to cut 45 - 75 seconds of audio to match the duration. Perhaps I'm not fully understanding your issue. Would you be do kind as to edit further detail into your post to help clarify the issue? – Elder Geek Mar 8 '17 at 18:59
  • It may not be as hard to remove silence as you think. – Elder Geek Mar 8 '17 at 19:33
  • Youtube speed adjustment feature is a client side script (the browser is doing it with javascript). There is no extra encoding process to make this feature available. If you are Web delivering this content in your control on your site, you can use javascript to auto play your videos at that speed. – user24601 Mar 8 '17 at 23:32
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You don't do this in Camtasia as it doesn't appear that Camtasia supports pitch shifting at this point although there has definitely been some discussion of the topic for quite some time.

There are alternate solutions however, ffmpeg has this capability through the atempo and aserate audio filters, I understand that you can do this with audacity and sox as well. If you have any interest in any of these approaches and would like further detail drop me a comment and I'll do my best to accommodate you.

According to @Mulvya you can also accomplish this with an ffmpeg build compiled to support librubberband You can compile it your self or there are Windows XP compatible builds available here which I've confirmed run under Wine

There's also a stand alone utility that I haven't used that you can obtain from the librubberband link above. It appears that that is limited to adjusting WAV files.

Some sources:

https://superuser.com/questions/292833/how-to-change-audio-frequency

https://superuser.com/questions/1118826/change-tone-pitch-for-file-audio

https://www.ffmpeg.org/documentation.html

https://feedback.techsmith.com/techsmith/topics/speeding_up_the_video_speed_without_effecting_audio_pitch

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  • 2
    The OP doesn't want to change pitch, so atempo and asetrate won't work. ffmpeg can be compiled with an external lib - rubberband, that will preserve pitch through tempo change. I don't know of a redistributable ffmpeg binary that has it. But it's also available as a standalone binary that works with WAV. – Gyan Mar 8 '17 at 20:34
  • @Mulva Yes rubberband. That's in my second source. Thank you. Is it your contention that chaining the filters aserate and atempo won't work on the source file before speed adjustment of the output file after speed adjustment. Thank you for your clarification. – Elder Geek Mar 8 '17 at 20:43
  • @Mulvya edited answer – Elder Geek Mar 8 '17 at 22:15
  • @Mulvya is right, I need to speed up the video but maintaining the same pitch. I have found it in Audacity which I am families with, through Effects -> Tempo. I am wondering what is equivalent to YouTube 1.25X in Audacity Tempo. – Mahdi Alkhatib Mar 9 '17 at 22:30
  • Mathematics says 1,25X = 125% – Elder Geek Mar 10 '17 at 13:03
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As I am familiar with Audacity I have found it through Effects -> Change Tempo...

enter image description here

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