I am using the Don Earl Engraved Color Reference Sync SlateWhen shooting with the Canon 5D Mark II, the only way to get great audio is to record it separately. Once production is finished we need to sync the audio and the video back together in post.

If you have taken the time to properly slate footage during production, the process is actually pretty quick and easy. There are, however, a few tricks with the 5D2 but once you get the process down it does not take long at all.

This is my process for syncing audio to the Canon 5D2 recorded separately using the Samson Zoom H4n recorder and Final Cut Pro. 

Step 1 - Find Matching Audio and Video Clips 

If the camera and audio recorder start and stop consistently it is really easy to match audio and video clips once you find the first one because they should progress forward evenly. It is good practice to verbally state the scene and take number before clapping the slate. This way you can audibly hear the scene and take and visually see the scene and take making it obvious which audio clip goes with what video clip. 

Step 2 - Find the Sync Points & Sync

Quickly find the sync in your audio by looking for a sharp spike in the audio.Finding the sync point is easy. In the video, find the frame where the slate closes. In the audio, look for a sharp spike in the waveform and mark in on the clap. 

If I am syncing a bunch of clips I will make a new sequence for each clip and add the full video to the sequence. The reason for separate sequence is so I can batch process everything when I bake in the audio (Step 5). Once the video is in the sequence I will find the sync points and add the audio to tracks A3 & A4. 

Step 3 - The 99.9% Solution

The Canon 5D Mark II does not record at a true 30fps. It is actually recording at its own funky rate 99.9% slower then 30fps. This is a problem. If you sync the dual system audio at the beginning of the clip after about a minute you will notice your audio is way out of sync. 

Setting the speed of your dual system audio to 99.9 percent solves the sync problem with the 5D.The solution is to change the speed of the audio not recorded on the 5D to 99.9%. Once you do this your audio will stay locked in sync for the duration of the clip.

At this point we are in sync and could start editing. However, for big projects and especially multi-cam projects I prefer to "bake in" the audio. Doing this, to me, is safer and keeps things better organized. Doing this renders the audio speed change into new synced master clips that I bring back into Final Cut Pro to start editing. This ensures that the audio and video will stay locked together throughout the post process.

Step 4 - Setup Audio Outputs

Adjust the audio outputs to 4 if you want to keep both audio sources.If you want to keep the on camera audio in addition to the dual system audio you will need to adjust your sequence settings before exporting. Open sequence settings and go to the audio outputs tab. By default you will have 2 audio outputs, increase the audio outputs to 4. This will keeps track A1 & A2 separate from tracks A3 & A4 in the new mater clips. If you do not do this you will mix both the camera audio and dual system audio together into 1 stereo pair. If you do not need the camera audio make sure you disable or delete those tracks before exporting.

Step 5 - Batch Export

There is a window in Final Cut Pro that I have never really had a good use for until now. The Export Queue.

The Export Queue allows you to batch export sequences. This is why I create a separate sequence for each clip. Drag all of the sequences into the export queue and confirm your settings are set to export same as source, select where to save the new master clips and click Export. 

Use the Export Queue to batch export and create new master clips.Final Cut will create new master clips, rendering the audio at 99.9% and baking it into the new quicktime files. The new master clips will contain 4 audio tracks if you decided to keep the camera audio. Once the export queue has finished creating the new master clips we are ready to start editing the project.

This may seem like a lot of extra steps but the process actually goes really fast once you get the workflow down. It is worth taking the time to get the project setup properly before you start editing.

Update on Thursday, March 25, 2010 at 5:58PM by Donald Kilgore

With the latest Canon 5D Mark II firmware update 2.0.3 (now 2.0.4) the camera will now record in proper frame rates that do not require changing the audio speed to 99.9%. This update not only adds the huge update of being able to record 24p but also records all frame rates to NTSC broadcast specs as well as PAL, solving the drifting audio sync problem. 

Canon 5D Mark II Frame Rates - Firmware 2.0.4

NTSC:

• 1920×1080 : 30 fps (changed - actual 29.97 fps)
• 1920×1080 : 24 fps (added - actual 23.976 fps)
• 640×480 : 30 fps (changed - actual 29.97 fps)

PAL:

• 1920×1080 : 25 fps (added - actual 25.0 fps)
• 1920×1080 : 24 fps (added - actual 23.976 fps)
• 640×480 : 25 fps (added - actual 25.0 fps)