Timecode values are a way to number frames in a video. Standardized by SMPTE, the video timecode is usually represented as hour, minute, second, and then the frame number.
We've all seen it. It's in the corner of our timelines, the viewfinder of our cameras, and hundreds of other places throughout the production process. But what do you really need to know about timecode in video production?
It's time to decode the timecode
The timecode is absolutely fundamental to video production. It can save time and money in production and can cause a lot of problems if not used correctly. As such, it's important to understand how video timecode works, how different frame rates affect you, and how to resolve potential timecode issues that may arise during your production process.
Timecode and frame rates
Understanding how frame rates work is important to understanding how the timecode is designed.
For example, an editor looking to place manual keyframes in a project every half second will find it helpful to know the exact number of frames each interval needs. Without knowing the frame rate at which the project was filmed, an expert editor could find this information quickly and make creative decisions based on that information.
The frame rate, the number of still images per second of video, can be difficult to visualize. For cameras, NLE, and ancillary functions such as audio synchronization, video runtime must be quantified in a consistent and decodable manner. To solve this problem, the standardized timecode was created.
Timecode values are a way to number frames in a video. Standardized by SMPTE, the video timecode is usually represented as hour, minute, second, and then the frame number, each separated by colons (:). For example, the sixth frame at 1 hour, 23 minutes, and 45 seconds of a video would be displayed as a timecode 01:23:45:06.
Understanding the standard timecode
When it comes to frames of integers per second, this can be easily converted to real times. For example, in a video with 30 fps, each frame is displayed for 33,333 milliseconds (repeated). This means that we can determine the actual moment at which that frame is displayed.
Similarly, in a video with 24 frames per second, each frame is displayed for 41,666 milliseconds (repeated).
For both 24 and 30 frames per second, the X-frame number within any second has the same offset as the X-frame number within a different second.
This is not true in the case of video with a frame rate of 30,000/1,001 (about 29.97 fps), such as NTSC television.
This variation of the timecode for non-integer frame rates grows continuously with longer videos. The deviation is six-tenths of a second from the actual viewing time. In another 10 minutes, there will be a difference of one full second between the timecode value and the actual viewing time.
In this particular case, there is a modification called Drop Frame Timecode where a few seconds of timecode have less than 30 frames.
Every minute except the tenth minute, two frame numbers are deleted. This can be confusing, but it is necessary to combat drift. The frame deletion timecode typically uses a semicolon as a separator before the frame number, rather than the colons that are used in the normal timecode.
Why does Drop Frame Timecode work? For every 10-minute segment of 29.97 fps video, there are 17,982 frames (10 minutes * 60 seconds per minute * 29.97 frames per second). Ten minutes of video at 30 fps would be exactly 18,000 frames. The difference is 18 frames, which explains why the standard of "frame deletion" is to delete two frames out of 9 out of every 10 minutes. The scheme removes 18 timecode frames every 10 minutes, which keeps the timecode value much closer to the actual viewing time.
It's worth noting that 10 minutes of video at 30,000/1,001fps would contain 17,982,018 frames (10*60*30,000/1,001), so the Drop Frame timecode doesn't perfectly model actual TV streaming speeds.
All in good weather
Understanding the ins and outs of frame rate and timecode can help you avoid potential problems with your production, giving you a better chance of a smooth editing process no matter how many cameras, cuts, and complexities you encounter. And when you consider the necessary precision and specificity that go into the timecode, as shown above, it can become much more complicated than one might expect when starting out.
It's more than just time. It's the timecode. Decryption.
*Jason Gyorog is a quality control engineer at Studio Network Solutions. The text was published by the company SNS.