How do I sync audio with video in VLC?

Syncing audio and video is the process of aligning separate audio and video files or streams so that they play back in perfect synchronization. This allows you to record high-quality audio using dedicated external equipment while capturing video separately. Syncing in post-production prevents distracting mismatches between lip movements and dialogue. While many video editing software packages offer advanced syncing capabilities, it’s also possible to manually sync audio and video streams using the free, open-source VLC media player. This guide will provide a step-by-step walkthrough of syncing audio and video files using VLC.

When Would You Want to Sync Audio and Video?

The most common reason to sync audio and video is when the audio gets out of sync from the video. This desyncing, also known as lip sync error, can occur for various reasons:

– Recording the video and audio separately can lead to sync issues if not aligned properly during editing and production.Help Center

– Encoding/compression of audio and video may happen at different speeds, gradually desynchronizing them over the length of a video.2024 Correcting Audio Video Sync Problems in Home Theater

– Playback problems like lag or delay in the audio or video signal paths can throw off sync.Help Center

Syncing the audio and video ensures the timing matches up properly for a quality viewing experience without jarring mismatches between sound and visuals.

Prerequisites

Before we get started, make sure you have VLC media player installed. VLC is a free, open-source video and audio player that supports many different formats. You can download VLC for Windows from https://www.videolan.org/vlc/download-windows.html, for Mac from https://www.videolan.org/vlc/download-macosx.html, and for mobile platforms from their respective app stores.

VLC runs on Windows, Mac, Linux, Android, iOS and Windows Phone. The latest stable release is recommended for the best syncing experience. Having VLC installed will allow you to open both the audio and video files and sync them together in the application.

Locate the Audio and Video Files

To sync audio and video together, you’ll need to have the separate audio and video files ready. Make sure you have both the video file that contains the video content, as well as a separate audio file that contains just the audio content you want to sync. The audio can come from the same original recording as the video, or it can be from a completely separate audio source like a music track or voiceover audio.

For best results, the audio file should match the length of the video file. If the audio file is shorter than the video, it will end before the video does. If the audio file is longer, the extra length will be ignored. Experts recommend recording audio and video together initially if possible, then separating them into individual files for syncing to get the best audio quality and ensure proper length.

Both the video and audio files should be in a format compatible with VLC media player prior to syncing. Common video file formats like MP4, MOV, and AVI usually work seamlessly in VLC. For audio, file formats like WAV, MP3, FLAC, and AAC are recommended.

Once you have your separate video file and audio file ready, you can move on to opening them in VLC to combine them.

Sources:

How to Automatically Sync Audio & Video Sources Easily

How to sync audio and video: 3 options with tips

Open the Video File in VLC

The first step is to open the video file that you want to sync the audio to in VLC media player. To do this:

Launch VLC media player on your computer.
Click on “Media” in the top menu bar and select “Open File…”

In the file explorer window that opens, navigate to the location of your video file and select it.
Click “Open”. This will open the video file in VLC.

Make sure to pause the video playback for now – we don’t want the video playing while we sync the audio. The video file is now ready to have the audio synchronized to it in VLC.

Source: https://www.videoconverterfactory.com/tips/vlc-trim-video.html

Open the Audio File in VLC

After opening the video file in VLC, you next need to open the audio file that you want to sync. This will usually be a music or audio track in a common format like MP3 or WAV.

To open the audio file in VLC:

Open VLC and click on Media > Open File from the menu.
Navigate to the folder containing your audio file and select it.
Click Open. The audio file will now load in VLC.

You should see the audio file waveform and playback controls. Make sure to listen to the audio briefly to confirm it is the correct file before syncing.

Now that both the video and audio files are open in VLC, you are ready to sync them.

Sync the Audio

Once you have both the video and audio files open in VLC, it’s time to sync them together. VLC provides two main ways to adjust the audio sync:

Use the audio sync slider – In the VLC menu, go to Audio > Audio Track Synchronization (or Audio > Audio Delay). A slider will appear that allows you to increase or decrease the audio delay in millisecond increments to match the video.
Use the sync shortcut keys – While a file is playing, you can press J or K on your keyboard to adjust audio sync. Press J to increase the audio delay and press K to decrease it until the audio matches the video.

Slowly adjust the audio sync using one of these methods until the audio is perfectly timed with the video. Getting the sync right may take some small adjustments back and forth. Concentrate on any speech in the video to help judge when the timing is correct.

For more precise control, try using the audio sync slider under the Audio menu. But the J and K keyboard shortcuts can also be very handy for quick adjustments while the file is playing.

Check the Sync

After syncing the audio, it’s important to preview the video to ensure proper sync before exporting. Play back a section of the video in VLC and watch both the visuals and listen to the audio carefully. The audio should match the visuals perfectly, with no lag or lead between what you see and what you hear. Pay special attention to sections with obvious audio cues, like someone’s mouth moving when they speak. If the sync is off, go back and adjust the audio track delay as needed until the sync looks right.

You may need to repeat this preview and adjustment process a few times to get the sync perfect. According to one source, “Although I can spot lip sync it’s hard for me to spot a few frames off.” So take your time and carefully check the sync in multiple spots in the video to confirm everything is aligned properly before exporting the final merged file. Patience here ensures your final video will have perfect AV sync.

Source: http://forum.doom9.org/archive/index.php/t-73901.html

Export the Synced File

Once you have synced the separate audio and video files in VLC, the next step is to export the file to save your work. Follow these steps:

Go to the “Media” menu in VLC and select “Convert/Save.”

Under “Destination file,” click the icon to browse and select where you want to save the exported file.
For the file format, choose a container like MP4 or MOV that will preserve both the audio and video.
Under “Video codec,” select H.264 or H.265 for a good balance of quality and file size.

For the audio codec, AAC or MP3 are good choices.
Adjust any other settings as desired, like the video resolution.
Click “Start” to begin the export process.

The progress will be shown and it may take some time depending on the file length and settings.

Once complete, you will have a new video file with the synced audio and video tracks combined. You can now share or use this new file in other video editors or players. Exporting the synced file is the final step to complete the audio sync process in VLC.

Conclusion

Syncing audio and video tracks in VLC media player is a straightforward process once you understand the basics. By opening your video and audio files in separate VLC instances and using the audio sync offset feature, you can accurately align the timing between the two tracks.

A few additional tips when syncing audio and video in VLC:

Use the same file formats for both audio and video when possible, such as .mp4 or .mov, for best compatibility.
Adjust the sync offset in small increments like 50-100 ms at a time to finely tune the alignment.

Preview your synced file before exporting to double check the timing.
If precise syncing is critical, consider using a dedicated audio/video editing software for more advanced capabilities.

With some practice using the tools in VLC media player, you’ll be able to efficiently sync audio and video tracks for your multimedia projects.