How to sync audio automatically

This article covers features which are only available in Silverstack Lab

In professional production environments, it is common to use a collective timecode to sync audio and video clips. Silverstack Lab enables you to perform this automatic audio sync easily.

All steps needed to perform this operation are explained in the article below. If you want to learn more about the audio user interface, visit the articles audio panel and audio sync wizard. This article also requires basic knowledge about offloading.

You need to perform the following essential steps:

Ingest video and audio clips into Silverstack Lab
Sync audio and video with the “Audio Sync Wizard”
Review synced clips in the playback view

1. Ingest audio and video clips#

Please refer to the articles workflow configurator and configuring a workflow to learn the essentials on offloading audio and video data. It is important to register the audio files separately from the video files into separate bins. Assuming you have registered or offloaded at least one video and audio card with matching timecode into Silverstack, select the video bin in the library and open the “Audio Sync Wizard.” There are different ways to do this:

Click on the Media button in the top left corner and select Sync Audio
Select the video bin in the library and Right-Click > Sync Audio…
Click the Audio & Color button in the top right corner and click the Sync Audio… button

Note: When ingesting mixed bins containing audio and video clips, you first need to separate both types into separate audio and video bins before running the audio sync. To do this, you can create new audio bins in Silverstack’s library outline and move the audio clips into these bins.

2. Sync audio and video#

Fig. 6: The audio sync wizard shows the matching video and audio clips

In the top section of the audio sync wizard you can choose the location of your audio clips that should be synced with the video clips. The table underneath displays the video clips on the left side and the associated audio clips on the right side, separated by a checkbox to enable the sync for each clip individually.Enable the Hide already synced video clips checkbox if you only want to view video clips that still need to be synced. Also check Import metadata from audio clips to video clips if you want to transfer metadata from the audio to the video clips.Please note that this will introduce an additional step of previewing the audio metadata import before the actual audio sync begins. In case you only want to sync specific video clips, you can use the Mark Only Selected or Unmark Selected buttons in the top right corner to select specific files. If you are ready, click Continue to proceed to the metadata import preview where you can check the metadata before it is actually imported into the library.

Click Sync or Finish to start the audio syncing (and import the metadata).

3. Review synced clips#

After the sync was executed, the external audio clips appear in the audio panel. If the video clips also contained internal audio, those tracks will be muted by default. Use the playback view to check the sync of your clips. You have the possibility to perform the following optional steps on an entire bin or a selection of clips:

Apply an audio offset to refine the sync and transfer it to other clips
Apply a mix to all clips in the bin
Re-sync audio
Lock and unlock external audio clips
Remove external audio clips

Apply an audio offset to refine the sync and transfer it to other clipsExternal audio clips that were synced via timecode can easily be slipped frame-wise to each side to change their position relatively to the video clip. Use the ←Δ and Δ→ buttons to slip/offset the audio by the defined amount of frames to the left or right.To transfer your audio offset to other clips, click the … button on the right of the audio header bar and select Apply Offset to All Timecode-Synced Clips . If you only want to apply the audio offset to specific clips, you need to select them first and then choose the appropriate entry.The Audio TC Offsets are also visible in the “Edit/User” section of the “General Info” and can be exported to reports and as metadata for source video clips and transcoded clips.

Apply a mix to all clips in the binAn audio mix consists of

Channel volume
Channel mute options
Channel routing (L/C/R)

You may mix your audio and transfer the mix of the current clip to other video clips. For example, it is possible to lower the volume, mute specific tracks, change the routing, and copy those settings over to other clips. To do so, click the … button and choose Apply Mix to All Clips in Bin .The audio track names are used for transferring the information. That means the audio settings will be taken over to channels with the same name in other audio clips.

Re-sync audioThis resets the “Audio TC Offset” that is applied when using the slip buttons. You can use this button to revert your manual changes. Single timecode-synced external audio clips can also be re-synced from the ⚙ menu of the external audio clip (e.g., if you have multiple audio clips that match one video clip).

Lock/Unlock External Audio ClipsYou can lock and unlock external audio clips to prevent the following actions from being applied:

Removal of external audio clips
Slipping of external audio clips
Application of Audio TC Offsets
Re-sync of external audio clips
Application of a mix

Clicking the 🔓 lock icon will lock the clip and indicate the locking status with a changed 🔒 lock icon.

Remove external audio clipsTo remove a single external audio clip for one video clip, click the ⚙ button in the header bar of the external audio clip and select Remove . To apply the same action for multiple clips, click the … button and select Remove All External Audio Clips .

Auto-sync with timecode vs. manual sync#

Silverstack Lab generally differs between an auto-sync by timecode and a manual sync via slate positions. While you can slip both types of external audio with the slip buttons, some functionality is not available for manually synced clips (e.g., applying an audio offset from a manually synced audio clip to other audio clips). When an external audio clip was synced via timecode, you can easily transition to a manual sync via slate markers that can be set in the audio track popover. To return to an auto-sync just re-sync the audio clip. Learn more about manual audio sync in the article How to Manually Sync Audio in Silverstack XT and Silverstack Lab.

Adding audio clips manually that qualify for auto-sync by timecode#

If you add audio clips manually that have timecode in common with the current video clip you have the option to sync them automatically by timecode. You can either choose to sync the audio clip based on timecode or leave the checkbox empty to sync based on slate positions in the audio and video clip.

Fig. 14: Add an external audio clip manually and sync it by TC