[UPDATED March 2021] Downloadable Audio/Video Sync Tests @ 23.98, 24, 25, 29.97, 50 & 59.94
These are my own custom audio sync tests, provided for you to freely download at all common frame rates of 23.98, 24, 25, 29.97, 50 and 59.94 fps. Need a custom frame rate? Let me know in the comments below; I'd be happy to make one for you.
Why you need these
All HDMI cameras have a slight delay between realtime and what's actually output over HDMI; this is simply inherent in HDMI processing and is unavoidable. When recording video, this is irrelevant. However when using an HDMI camera in a live production situation, if you're mixing video from the camera and audio from another source, the audio will generally be in real time while the video will not, resulting in an audio/video mismatch. Devices like the ATEM Mini Pro have the ability to program in a delay for the audio, so is in sync with video. If you're using a professional sound mixing board, the board can typically program a delay into it in milliseconds, so the audio actually arrives to your switcher / streaming hardware at the same time as the video.
These custom videos allow you to measure the delay so you can program it into your hardware.
How to use them
- Download the video(s) for the appropriate frame rate to a laptop or tablet (the bigger the screen, the easier it will be to see this). It's critical that you use the matching frame rate to your production, or this won't work!
- Position your laptop/tablet where the talent will be, play back the downloaded sync test (full screen and full volume is best), and point your HDMI camera at the screen. Ensure that the microphone is in (close to) the same position it will be for the production, that the microphone can clearly pick up the BEEP from sync test video, and that you can clearly see the sync test video on camera.
- Shoot video of the test; at least several seconds, but 30 should be more than enough. It's helpful to run it for more than just a couple of beeps so you can verify there is no variance from the beginning to the end of the clip.
- Load the recorded clip into an NLE and look for the BEEP on the audio waveform. Place the playhead there and look at the video; wherever the red speaker dot is, indicates how many frames you need to adjust. For example if the red dot is at the –4 mark, then your audio is four frames BEFORE the video. Add a four frame delay into the hardware. If your hardware programs the delay in milliseconds, use the chart to see how many seconds/milliseconds the delay is.
You can play these from YouTube directly, however I recommend against that as there's no way to know if YouTube is delivering the video perfectly in sync. Download the appropriate frame rate video, and you can download these in 4K or HD.
(option-click to download)
23.98 (23.976) fps audio video sync test
24.00 fps audio video sync test
25.00 fps audio video sync test
29.97 fps audio video sync test
50.00 fps audio video sync test
59.94 fps audio video sync test
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