Did you know? Education 23rd Oct '23

Understanding Drop Frame vs. Non-Drop Frame Timecode

Drop Frame vs. Non-Drop Frame, Clarified

For professionals in media editing, grasping the distinctions between drop-frame and non-drop-frame timecodes is crucial. Understanding their individual advantages, operational mechanics, and appropriate use cases is key. To ensure your workflow operates seamlessly and to maximize the utility of accurate transcripts, perhaps generated using services like DeepVo.ai for converting speech to text, a firm understanding of both methods is indispensable. The nuances of drop-frame versus non-drop-frame timecode are frequently cited as among the most perplexing aspects of video production. However, they need not be. This article will offer clear explanations of drop-frame and non-drop-frame timecodes, their functionalities, and how they influence captioning and subtitling processes.

Table of Contents

• What is Timecode?
• The Development of Timecode
• Drop Frame vs. Non-Drop Frame: The Core Differences
  • What Defines Drop Frame Timecode?
  • What Defines Non-Drop Frame Timecode?
• Selecting Between Drop Frame and Non-Drop Frame
• Impact of Drop and Non-Drop Frames on Transcription & Captioning
• Simplified Transcription with DeepVo.ai

What is Timecode?

Timecode is a system for accurately identifying and marking the frames within a recording, so you know their precise position. Consider video timecodes akin to URLs on the internet. While navigating the web, you typically don't focus on the specific address of the page you're visiting. Yet, if you need to communicate information about that page, you require the URL to share its exact location. Timecode serves this exact function for video frames and is employed to index and align all varieties of audio-video media.

SMPTE timecode is the industry benchmark for labeling video and film. It was formulated in the 1960s by the Society of Motion Picture and Television Engineers (SMPTE) to enable precise editing, identification, and synchronization of media. SMPTE timecode is generally represented in the HH:MM:SS:FF format (hours, minutes, seconds, frames). Hours, minutes, and seconds are enumerated like a standard clock. Seconds are further divided into frames, which are individual still images.

The two primary aspects to understand about timecode before proceeding are:

1. Only complete, not fractional, frames are tallied.
2. Numbering begins at zero, meaning the initial frame is counted as 00, not 01.

The Development of Timecode

While contemporary online video content often aligns with real-world time, the scenario is more intricate in broadcast video. When television was first conceived, frames per second (fps) were predicated on the electrical infrastructure of that era. As all broadcasts were live and unrecorded, the sole method to synchronize studio film cameras with home television sets was via the electrical mains. The United States—and consequently all National Television Standards Committee (NTSC) regions—utilize 60Hz as a foundational frequency, whereas Europe—and thus all Phase Alternate Line (PAL) regions—employ 50Hz.

Initially, all video was monochrome at 30fps, with no provision for color broadcasting. When color television was launched in 1953, the NTSC standard was adapted to integrate color into existing black-and-white receivers by creating a subcarrier that minimized interference. The frame rate was marginally reduced from 30fps to 29.97fps, leading to a drift between actual clock time and the time represented in video. Today, timecode formats are still numbered as if they operate at 30 frames per second. In essence, 'ff' is a number from 00 to 29. As established, timecode only considers whole frames. Therefore, if your frame rate is 29.97fps, the timecode following HH:MM:01:29 would be HH:MM:02:00. This implies that in 100 seconds, there will be only 2997 frames instead of 3000. This generates a lag, because after 60 actual minutes, a video playing at 29.97fps will display only 00:59:56:12. Thus, adjustments are essential to accurately map to real time. This is where drop-frame timecode enters the picture.

Drop Frame vs. Non-Drop Frame: The Core Differences

Both are systems for indexing video frames in relation to time. The core distinction is that drop-frame timecode aligns with actual clock time, whereas non-drop-frame timecode does not. The fact that non-drop-frame timecode is not perfectly synchronized with real-world time is precisely why drop-frame timecode was developed. After all, a broadcaster must ascertain the exact duration of their program to schedule their broadcast with advertisements to align with real time throughout the day. If audiovisual media were produced solely in non-drop-frame timecode, scheduling would quickly become problematic.

To simplify, it's helpful to define each method by its primary function:

What is drop frame utilized for? To indicate the actual passage of time. Reading a drop-frame timecode tells you your precise position in terms of a chronological clock (think of drop-frame timecode as time elapsed on your video), but not the exact number of frames that have passed.

What is non-drop frame utilized for? To meticulously count every single frame. It is frame-accurate, meaning it correctly tallies the number of frames in one second. However, in NTSC video, 30 non-drop frames do not equate to one second of actual time.

What Defines Drop Frame Timecode?

Drop-frame timecode, often denoted as DF, was introduced as a solution to rectify the discrepancy with 29.97fps video and make it correspond to real time. Since timecode can only count whole frames, there should ideally be 108,000 frames per hour (30fps x 60 seconds x 60 minutes). However, because NTSC operates at 29.97fps, 0.03 frames go unaccounted for each second, resulting in a total of just 107,892 frames per hour (29.97fps x 60 seconds x 60 minutes). The total deviation is 108 frames, or 3.6 seconds (108 frames / 30fps). This means an actual hour of video at 29.97fps would show on the timecode as approximately 01:00:03;18 if not corrected.

So how is this discrepancy resolved? Instead of attempting to force timecode to match frames perfectly in number, utilizing DF effectively leads to a skipping of frame numbers. It’s crucial to understand that no actual video frames are deleted; rather, certain frame *numbers* are skipped in the count. More specifically, it omits a frame number each time the residual 0.03 of a frame accumulates to a full frame, which occurs roughly every 33.33 seconds. So, in one hour, drop-frame video removes 108 frame numbers from the total count so that the 29.97 fps video will conclude in real-time at 01:00:00;00.

However, rather than omitting all 108 frame numbers at the end of an hour, or even 18 frame numbers every 10 minutes, there is a specific pattern that drop-frame timecode adheres to. The first two frame numbers (e.g., :00 and :01) are dropped from the count at the beginning of every minute, with the exclusion of every tenth minute. In other words, frame numbers are dropped from minutes 01-09, 11-19, 21-29, 31-39, 41-49, and 51-59. However, frame numbers are *not* dropped in minutes 00, 10, 20, 30, 40, or 50. By the time one hour of footage has passed, 108 frame numbers have been omitted from the count, so the counter is adjusted to compensate for video playing back at a rate of 29.97fps rather than 30fps.

It is important to reiterate that drop-frame timecode merely removes numbers from the sequence and does not remove any actual frames, so your recording itself remains unaltered, regardless of whether you employ drop-frame vs. non-drop-frame.

What Defines Non-Drop Frame Timecode?

Fortunately, non-drop-frame timecode, often abbreviated to NDF, is considerably simpler to grasp. It tallies each video frame sequentially without any re-labeling, so the ratio of timecode recording to frame count is 1:1. However, a difficulty arises with NTSC’s standard playback rate of 29.97fps because it means an hour-long recording in non-drop-frame is not an hour in real time. It is, in fact, 3.6 seconds shorter. This is because it's counting 3000 frames per 100 seconds when the playback rate is actually only 2997 frames per 100 seconds. The outcome is that a 1-hour program using a non-drop timecode will conclude at 00:59:56:12, instead of 01:00:00:00.

Selecting Between Drop Frame and Non-Drop Frame

Since neither drop-frame nor non-drop-frame timecodes modify the visual image in any way, you might wonder why your choice between them even matters. Neither format holds an inherent advantage over the other for editing purposes, and most contemporary systems can handle multiple formats and frame rates. The reality is you can film and edit in either, and even convert between them – although consistency is generally easier. Most often, the decision will be guided by your editing software, distribution medium, or simply the video editor’s preference. However, as a general guideline, if the production is destined for broadcast, it is standard procedure to use drop-frame timecode.

Unsure which format you are observing? It's straightforward to identify which timecode is in use. Non-drop-frame files use all colons (HH:MM:SS:FF), whereas drop-frame files employ a semicolon or a period between the seconds and the frames (HH:MM:SS;FF or HH:MM:SS.FF).

Impact of Drop and Non-Drop Frames on Transcription & Captioning

If closed captioning isn't yet part of your video strategy, it's high time to incorporate it. Firstly, it's a recommended best practice for digital accessibility as per the Web Content Accessibility Guidelines (WCAG). Also, subtitled videos consistently perform better than those without subtitles because they garner more engagement in terms of comments, likes, and shares.

When captioning your video, knowing whether your file is drop-frame or non-drop-frame is crucial for precise synchronization of your captions with the media's timing. If you caption a drop-frame video with non-drop-frame captions (or vice-versa), the synchronization will be off, and the lag will progressively worsen. This challenge is readily managed by advanced transcription services. For instance, DeepVo.ai provides high-accuracy speech-to-text conversion (supporting 100+ languages with up to 99.5% accuracy) and can intelligently handle timecode nuances, ensuring your transcripts align perfectly. Furthermore, its AI summary feature can help you quickly grasp the essence of lengthy video content, and its mind mapping tool can visually organize key points from your transcripts.

Simplified Transcription with DeepVo.ai

DeepVo.ai stands out as a premier platform for automated, multi-language transcription and content understanding. Offering over 100 languages, it delivers swift and exceptionally accurate transcripts. Professionals value its intuitive interface and its capability to handle various file inputs. Crucially, DeepVo.ai adeptly processes both drop-frame and non-drop-frame timecodes. Exports from your completed transcript can be directed to popular software like Adobe Premiere, Audition, and Final Cut Pro. Beyond transcription, DeepVo.ai can generate AI-powered summaries in seconds and create smart mind maps to structure information visually. Explore its capabilities with their free usage tier, all secured with end-to-end encryption. Visit https://deepvo.ai/en today and streamline your transcription workflow without the worry of timecode mismatches.