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Ok, so I found out that Blender has this really cool video-editing interface and I was beginning to love it. Until, I created this awesome project composition and when I exported the animation as a video file, the audio was out of sync :(.

Actual Problem

  • Audio is in-sync with video when the animation is played in Blender but is out-of-sync in the rendered video.
  • I know that this question has been asked umpteen number of times already, but no solution seems to work.

Solutions I tried out and failed

  • I used the 'Audio-Sync' option in the sequencer but that made no difference.

  • Then I thought that my scene audio frequency might have been an issue since it was initially 48kHz and my videos were at 24kHz, so I changed the scene audio frequency to 24kHz, this still failed to solve the issue.

  • Initially, I was combining videos with different frame rates and thought that might have been an issue (although animation played as expected in Blender), so I recreated the source videos to ensure all videos I was using in my project had the same frame rate, but this also did not work.

  • Someone online suggested exporting the video and audio separately and then combining them using a command-line tool like FFMPEG, this also failed.

What's really frustrating

  • This lag (audio is a few frames ahead of the video) is noticeable only in longer videos (>12 mins, my video is 1 hr long) suggesting a very small rendered rate difference between the video and the audio.

  • Also, note that the animation plays absolutely fine in Blender, so all I could figure out was that this was a rendering issue.

So if anyone figured this out please let me know. I am a noob in video/audio codecs so please forgive me if I used some incorrect nomenclature above.

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  • $\begingroup$ Well... I was really hoping you hadn't made sure "AV-sync" was on, but looks like you did. Oh well :P May be having to do with frame rates being different than the blender scene framerate. This looks like something that is not supposed to happed, so you might find help on developer.blender.org, blender's official bug tracking site. Have fun! :) $\endgroup$ – ZargulTheWizard May 22 at 0:24
  • $\begingroup$ @ZargulTheWizard, sure thing. I will post my query on developer.bender.org. $\endgroup$ – Siddhant Shenoy May 22 at 23:37
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So after a lot of online searching, I did find an answer to fix this problem, but not in Blender. If you are like me and would like to use Blender for video editing and still get around the issue, then I found a workaround, but you need Shotcut for this. Shotcut is another great free and open-source video editor

  1. Export the entire long video from Blender (the rendered video has desync issues as expected).
  2. Open the video in Shotcut and detach the audio from it.
  3. Use the audio properties to make very fine adjustments to the audio playback speed to suit your requirements (make fine adjustments until video and audio are in sync).

Follow the GIF attached. (I am using a shorter video in the GIF but you get the idea)

enter image description here

Explanation

  • Blender has issues while rendering long videos and I noticed that the video is exported at 1.0x speed but the audio is sometimes faster (1.00400x or something like that) and hence the rendered video has audio not in sync with the video.
  • Another bad thing is that Blender does not really allow very fine playback speed adjustment just to the audio.
  • One trick is to adjust the pitch of the audio in Blender which in turn changes the playback speed but this is only allowed up to 2 decimal places (not what we want for long videos) and it makes the audio sound funny (since it actually changes the pitch).
  • Shotcut is a great tool that allows fine playback adjustment, and it also has a pitch compensation feature so that your pitch is kind of unaffected (since we don't want the characters to be sounding funny in our edited video).
  • Shotcut allows playback speed adjustment up to 6 decimal places.

I have also created a short video about this, which can be found here.

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