Adri's Audio » Timecode for location sound recording

Timecode research

To create a film, productions usually shoot video and audio on separate devices to capture better quality audio/video for a finished film. This is known as a double system, whereas a single system would have audio and video recorded together on one device. Film professionals use a tool known as timecode to sync devices. Timecode is set on both devices in a compatible format between the two recorders. The frame rates for both devices can be altered to make files compatible in post-production. If a camera was recording at 29.97 fps (frames per second), that would be compatible with an audio recording at 29.97 fps or 23.976 fps. While this example refers to color television, there are many other compatible frame rates that will work for different formats.

Frame rate depends on intended format release. Additionally, the preferences of a post production team influence the frame rate used, as they will be the ones directly handling each file and producing the final cut. The editing software that post production decides to use also influences this heavily. Non drop frame is usually favored in film, but drop frame will sometimes be used if there is special permission given from a post production team. While many factors go into this decision, it is important to get this decision in writing. You may be told something by a boss, but then reprimanded later when there is a sudden change. To avoid this, having proof of a previous decision is vital.

As previously noted, most films use non drop frame as opposed to drop frame in terms of frames per second. The difference between these two can be difficult to understand, so understanding the format first can be helpful. Non drop frame will be shown as 00:00:00:00, where the zeros represent hours, minutes, seconds, and frame rate. Drop frame on the other hand can be shown as 00:00:00;00, 00;00;00;00, or 00:00:00.00. At a glance, it is easy to see the difference here is that instead of colons separating each piece of information in non drop frame, there may be a semicolon or period separating information. The main difference between the two is how many frames per second are used. Non drop frame typically uses 30 fps, whereas 29.97 fps typically refers to drop frame. When calculating how many frames per hour, 30 fps results in 108,000 frames per hour, while 29.97 fps calculates to 107,892 frames per hour. This is a substantial difference!

Sample rate and bit depth are usually 48 Khz and 24 bits. Changing either one the slightest bit can result in a drastic change. Sometimes 48.048 KHz may be used, but only for special cases. If a film set to release in video format is being produced, in -F stamping, this may be a worthwhile sample rate to use. If this is the rate used, video cannot shoot at any frame rate other than 24 fps. Otherwise the recordings will not match pictures, which will make things extremely difficult in post production. When transferring data for dailies and such, sound and video experience what is known as a pulldown, where 0.1% of the sample rate is altered so data can be processed. Depending on the intended release, it may be pulled back up or kept at the 0.1% pull down. 48.048 KHz is ideal for many post production teams because a 0.1% pulldown results in the audio to be exactly 48 KHz. If audio files are sent to Pro Tools for editing, the application will automatically convert any file to be 48 KHz if it is not already. There are many benefits to 48.048 KHz, but if the sound or post production teams are unsure if they will benefit from this, it is not worth using this sample rate.

Works Cited

Gyorog, Jason. “Decoding Timecode Standards in Video Production.” SNS (Studio Network Solutions), 20 May 2021, www.studionetworksolutions.com/decoding-timecode-standards-in-video-production/.

Rapp, Henri. “How to Sync Audio for Modern Video Production Workflows.” No Film School, No Film School, 14 Dec. 2020, nofilmschool.com/how-sync-audio-modern-video-production-workflows.

Sdadmin. “Sample Rate and Frame Rate Settings for Production Sound.” Sound Devices, 2 Apr. 2019, www.sounddevices.com/sample-rate-and-frame-rate-settings-for-production-sound/.

Webmaster. “48.048 Khz?” Trew Audio, 16 May 2017, www.trewaudio.com/articles/48048-khz/.

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