Film Timing (Timecode) Calculator • Film Industry Calculators • Online Unit Converters (2024)

This calculator converts the timecode to the number of frames. It can also add or subtract two timecodes. This need often arises when editing videos. The timecode represents the time in the form of hour:minute:second:frame format (HH:MM:SS:FF). The range of timecode is from 00:00:00:00 to 23:59:59:FF. The FF value can be 16, 23.976 (23.98), 24, 25, 29.97, and 30 frames per second (fps). You cannot enter the FF value that exceeds the selected frame rate.

Example: Calculate the number of frames in the sum of two timecodes 01:25:12.23 and 00:21:05.02 if the frame rate is 23.98 fps.

Example 2: Calculate the number of frames in the difference between two timecodes 23:59:59.59 and 01:21:05.02 at 60 fps.

Frame rate, fps

fps

Timecode 1

HH MM SS FF

+–

Timecode 2

HH MM SS FF

Total

HHMMSSFF

s

To calculate, enter one or two timecodes, select the plus or minus operation and click or tap the Calculate button.

Definitions and Formulas

What is Timecode?

Timecode (spelled also as time code) is the system, which assigns a unique number to each frame of a video to allow it to be uniquely identified. In other words, timecode is the information about the absolute or relative recording time of a video frame or audio recording. The timecode represents the time in the form of hour:minute:second:frame format (HH:MM:SS:FF). For example, in the slate picture above, the timecode shows that the picture begins at 10:29:01:00 (10 hours, 29 minutes, 01 seconds, 00 frames). The clip above runs at 24 frames per second from 10:29:01:00 to 10:29:04:24 or exactly 4 seconds. A timecode slate (clapperboard) has a display that shows the timecode of the video and audio. The timecode is jammed (entered) into the clapboard when it is connected by a wire to the camera, audio recorder, or timecode generator.

This timecode represents a time reference of 12 hours, 54 minutes, 5 seconds, and the 23rd frame

The range of timecode is from 00:00:00:00 to 23:59:59:FF. The FF value can be 16, 23.976 (23.98), 24, 25, 29.97, and 30 frames per second (fps). The timecode in this form is defined by the Society of Motion Picture and Television Engineers (SMPTE). It is added to the film, video, and audio material and is also used in music and theatrical production. The DF suffix on 29.97 and 59.94 in the frame rate selector indicates that these two timecodes use the drop-frame method. It is described below. There is no drop-frame for 23.976 fps.

The full number of frames FF_full is defined from the timecode in the form HH:MM:SS:FF as follows:

Here fps is the frame rate in frames per second.

In digital form, timecode is typically represented in the form of a 32-bit word representing time, frame number, and other information. In audio form, the timecode uses frequency modulation (FM).

Why is Timecode?

One can ask a reasonable question: “I make a video for my vlog every day and I don’t understand what is timecode and why should I use it, if it’s possible to sync everything in post-production?” The answer is yes, it is possible BUT doing it manually is very inconvenient and time-consuming. If the video footage contains timecode, an editor can move to any frame in just one click because the timecode shows the exact address of every frame. It also shows the exact time at which this frame was taken. Timecode also allows the people making a video to take production notes. And, most importantly, it allows you to easily synchronize video and audio material captured and recorded by various devices. Without timecode, editing would be very tedious and difficult.

If only a smartphone on a tripod is used for shooting, there is no problem. However, if you need to use two or three cameras and record sound on a separate recorder, then this is a completely different situation. In this case, it is already desirable to use a professional audio recording device and record timecode from one source (a professional audio recorder can be that source) on all devices. Without this, you can, of course, do editing, but it will take quite a lot of time, especially if the shooting and post-production is done by a team. Therefore, in this scenario, of course, all equipment must be synchronized from the same timecode source.

Why is 29.970 and Not 30 fps?

Why does the world use different frame rates and not just one rate of 24 frames per second that was adopted for shooting on film? This is due to the advent of television. The TV set needs frame synchronization to work, which tells it when to start the next frame. This frequency should coincide with the mains frequency — otherwise, a slowly moving band could appear on the image. In addition, TV studios would have big problems with flicker when creating TV programs. By the way, this problem exists even in modern digital cameras where special modes have to be provided to suppress flicker as a result of a mismatch between the mains frequency at the shooting location and the frequency of the video camera clock generator.

Such a requirement to march the synchronization frequency with the mains frequency is because the first TV programs went live and the natural way to synchronize cameras in the studio and on home TVs was to use a fairly stable mains voltage frequency. At that time, and this was almost a hundred years ago, no one thought about digital video and the problems that would be created for it. In European power networks, a frequency of 50 Hz was used, and in American — 60 Hz. As long as television was black and white, there were no issues with frame rates. However, when the development of the NTSC standard for color television began in the US, it was necessary to ensure its compatibility with many black-and-white TV still used by people. To do this, they had to slightly reduce the frame rate and instead of 30 fps, they got 30/1.001=29.970 fps. This frame rate made it possible to reduce the interference appearing on the screen.

Since the minimum timecode increment is one frame, rather than a fraction of a frame, it turns out that every second 0.03 frames are lost and a device running timecode at 29.97 fps is running slightly slower than a conventional clock. Another way to look at this problem is to say that 29.97 fps means that 2997 frames instead of 3000 frames are recorded or played back in 100 seconds.

In Germany, the PAL system, a modification of the American TV system was developed. It was designed for the mains frequency (and half-frame rate) of 50 Hz and to overcome the NTSC’s shortcomings. It is accepted in most countries with the mains frequency of 50 Hz.

Approximately at the same time, in France, the SECAM system was developed, which is incompatible with the NTSC system. This incompatibility allowed the French to protect their domestic video producers from competitors from the US. It allowed protecting of French TV equipment manufacturers as well. The same system was adopted in Eastern European countries and in the USSR to ensure incompatibility with Western transmissions.

Timecode Modes in Cameras

Free-Run Timecode

This type of timecode is often called just “free-run” and is used if it is necessary to know the actual time at which certain events being recorded occurred. In free run, the time code keeps advancing even when the camera is not recording. It is useful for recording sports or documentaries that last several days. In this mode, the camera runs timecode continuously regardless of whether the shooting is in progress or not. The timecode runs at the camera’s frame rate. On professional audio recorders, the frame rate must be set up by the person who operates it. It is convenient to set the timecode to the time of the day. The only thing to remember when using the free-run timecode is that there will be a small drift between the camera timecode and the actual time of day. This mode is often used when the shooting is made using several cameras and professional audio recorders.

Record Run Timecode

In this mode, the camera or audio recorder runs the timecode only during recording. Time codes in the next recorded movie file continue from the last time code in the previous file. Because it counts only the recording time, the total runtime reflects the total usable footage. Record run timecode is a good option if only a single camera with an audio recorder is used for shooting.

Drop-Frame vs Non-Drop Frame Timecode

As we mentioned earlier, with the NTCS frame rate of 29.97 fps, 0.03 frames are unaccounted for every second. Because of this, there will be 30 fps × 60 s × 60 min = 108,000 frames in an hour of 30 fps shooting and 29.97 fps × 60 s × 60 min = 107,892 frames of 29.97 fps shooting. So, there is a discrepancy of 108 frames or 108 frames / 30 fps = 3.6 s between one hour of real time and one hour of shooting time, which will be 01:00:03:18 instead of 01:00:00:00. The drop-frame mode allows returning the timecode to exactly one hour by dropping frames #00 and 01 at the beginning of every minute except for every 10th minute. This works almost like determining a leap year. Note that in drop-frame mode, only frame numbers and not actual frames are dropped.

Linear Timecode Data Format

This timecode format is used to record it as an audio signal and to transmit it over analog communication lines. For example, it can be recorded into audio tracks of several prosumer cameras from an inexpensive timecode generator and later used for synchronization. This type of timecode synchronization is often used for shooting low-budget movies.

You can listen to this code by clicking on the link above. You can hear that the fundamental frequency is equal to the frame rate of 25 and 30 Hz. The high-pitch sound is due to a waveform with a frequency of 1 kHz (for 25 fps). This is approximately the note b” (B of the two-line octave or B5 in scientific notation).

The basic timecode format is shown in the picture above. Click the picture to enlarge it. Linear timecode is an 80-bit code in the form of a sound signal modulated using differential Manchester encoding (also called biphase mark code). The data stream is self-synchronized, that is, the data and clock signals are combined, which can be seen in the picture above.

Various bits of the code sequence have the following meaning:

• bits 00–03 Frame number, units (0–9)
• bits 04–07 User bits, field 1
• bits 08–09 Frame number, tens (0-2)
• bit 10 Drop frame flag
• bit 11 “Color frame” flag
• bits 12–15 User bits, field 2
• bits 16–19 Seconds, units (0–9)
• bits 20–23 User bits, field 3
• bits 24–26 Seconds, tens (0–5)
• bit 27 Binary group flag
• bits 28–31 User bits, field 4
• bits 32–35 Minutes, units (0–9)
• bits 36–39 User bits, field 5
• bits 40–42 Minutes, tens (0–5)
• bit 43 Binary group flag
• bits 44–47 User bits, field 6
• bits 48–51 Hours, units (0–9)
• bits 52–55 User bits, field 7
• bits 56–57 Hours, tens (0–2)
• bit 58 External clock synchronization flag
• bit 59 Binary group flag
• bits 60–63 User bits, field 8
• bits 64–79 Sync word, fixed bit pattern 0011 1111 1111 1101

A complete description of the linear timecode format is beyond the scope of this article. The timecode shown in the picture above means the following:

• Time and frame of the current frame: 01:00:00:01 (HH:MM:SS:FF).
• Time and frame of the second frame: 01:00:00:02 (HH:MM:SS:FF).
• No drop frame (bit 1 is set to 0).
• The time code is not synchronized to a color video signal (bit 11 is 0).
• The time is not synchronized to an external clock (bit 58 is 0).

The frequency of this high-pitch sound is 1 kHz because, in differential Manchester code, which is used for encoding, two 0’s make up one period of a rectangular pulse signal. Several 1’s give a high-pitched tone with a frequency of 2 kHz or approximately note b’’’ (B of the three-line octave or B6 in scientific notation). It is easy to calculate this frequency if we multiply the 25 Hz frame rate by half the number of bits in the one-frame code (40): 25 · 40 = 1 kHz.

This article was written by Anatoly Zolotkov

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In this part of the TranslatorsCafe.com Unit Converter, we present a group of calculators related to various aspects of the film industry, which is involved in the creation and distribution of films (motion pictures). This industry employes a larger number of people that can be divided in two groups: those in front of the camera (actors) and those behind it (directors, producers, screenwriters, sound designers, and many others).

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