Understanding Standards: Time Code

Standards drive many technologies that we use in our day-to-day lives, from media to medicine to food production—yet the average person is not aware of the invisible role that they play. As a Standards Developing Organization (SDO) with over a century of accomplishments, SMPTE and its members strive to create a more interoperable world. In this series, we will explore SMPTE Standards in a way that’s easy to understand. Today’s Family of Standards: SMPTE Time Code.

              Also known as “Time and Control Code” and “SMPTE ST 12” this Standard, and its various parts, specifies a time and control code for use in video and audio in television systems operating at nominal rates of 60, 59.94, 50, 48, 47.95, 30, 29.97, 25, 24, and 23.98 frames per second. Its supports interlaced as well as progressive applications and offers a drop frame mode. SMPTE ST 12-3 extends the frame rates to 72, 96, 100 and 120 frames while being backwards compatible with SMPTE ST 12-1 and -2. Drop frame mode is only supported for 120 frames in this standard.

In other words, SMPTE ST 12 labels individual frames or fields of analog or digital audio and video using a sequence of numeric codes (hour:minute:second:frame) generated at regular intervals by a timing synchronization system. SMPTE ST 12-1 and -2 also offers user bits (32 bits) which can be customized for various application like, identifiers, event markers, automation or metadata. The user bits are used by SMPTE ST 12-3 to accommodate the higher frame rates.

              The SMPTE Time Code has been around for more than 50 years and received several updates throughout the years to adjust it to new technologies like high frame rates. The Time Code suite of Standards include:

• SMPTE ST 12-1: Time and Control Code
• SMPTE ST 12-2: Transmission of Time Code in the Ancillary Data Space
• SMPTE ST 12-3: Time Code for High Frame Rate Signals and Formatting in the Ancillary Data Space

Even after 50 years, Time Code Standards are still some of the most downloaded Standards SMPTE has to offer. It sees widespread use in both film and television and has many applications. For example, time codes can be logged by the camera assistant so shots can be referenced during production and post-production. Time Code Standards can be downloaded from the SMPTE Store. For more information on Standards, visit the SMPTE website smpte.org.

Stay tuned for more simple explanations for the Standards that make everyone’s lives better! For more information on SMPTE, our Standards, our education initiatives, or our events, please feel free to connect with us!