How to extend a track in audacity

I"ve demuxed an audio commentary track from a DVD release of a movie. My plan is to mux this commentary track ago into a Blu-Ray variation of the movie. However, the trouble is that the Blu-Ray is 4 minutes and also 15 secs longer than the original.

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Because of this, I desire to modify the original audio track so that it is progressively extended out to accommodate the extra couple of minutes of footage, ensuring that it doesn"t reduced out prior to the movie does. However, I likewise need to make sure that doing so doesn"t change the sound too much.

How can I do this in Audacity? I"ve come across both the Change Tempo and also Paulstretch filters, but I"m not certain just how or also whether I can usage these to accomplish what I"m in search of.

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edited Apr 21 "19 at 0:57
Hashim Aziz
asked Apr 21 "19 at 0:09

Hashim AzizHashim Aziz
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I was able to attain this utilizing the Change Speed filter and then adding an initial delay to the track utilizing the MKVToolNix GUI.

Note: This technique does come with the downside of altering the pitch of the audio track slightly.

You might have the ability to minimise or also entirely eliminate this adjust of pitch by determining the delay to be added, manually including it using Audacity"s Silence filter and also then using the Change Speed filter, however bereason I was taking care of a fairly unvital audio commentary track, a slightly deeper pitch wasn"t sufficient of a deal-breaker for me to warrant spfinishing the extra time on.

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How to stretch an audio track via Audacity

Import the audio track you desire to stretch right into Audacity using Documents > Import > Audio, or CtrlAltI.

Select the totality of the imported audio track using CtrlA.

Select Effect > Change Speed. In the dialogue that shows up, select the new desired length of your audio track (i.e. the length that you desire the audio track to be stretched to):


Click OK and wait for Audacity to process the track - this shouldn"t take even more than a minute to complete.

Chances are that your newly-extended audio track will currently be out of sync via your original video stream. Due to the extended audio no much longer equivalent the timestamps of the original video, it"ll be impossible to sync both together as exactly as the original. This provides the entire process of extending audio to fit a video clip unsuitable for millisecond-dependent audio content choose dubs, yet it have the right to be enough sufficient for scores and audio commentaries once adequately synced up.

Keep in mind that the remainder of this overview assumes that you"re muxing the extended audio track in addition to the original video stream right into an .mkv container. If muxing to a container other than .mkv, you"ll should look for a tool that supports adding a delay to that container.

Syncing the extended audio track with MKVToolNix GUI

Download MKVToolNix from below. After installing, make sure to follow the links to downpack and also install MKVToolNix GUI if vital.

Once mounted, launch MKVToolNix GUI. Click Add Source Files to import any streams you want to mux into your output video, making sure to include your original video stream and the audio track you stretched in Audacity. Once the stretched audio track appears in the list of tracks to be muxed into the output video, pick it.

In the Properties pane to the best, include a delay to the track in milliseconds, where 1 second = 1000 ms:


Keep in mind that the specific worth you must enter here will be totally dependent on your video, so will certainly take some trial-and-error to recognize. I recommend initially muxing your extended audio track right into the video through no delay, then watching the resulting output to determine exactly how much of a delay is necessary to sync up the extended audio through what you watch on-screen.

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To complete, offer a name to the output video in the Desticountry file field, then click Start multiplexing to mux all of your tracks right into a final .mkv video.