ISO/IEC 11172 Specifications for MPEG-1, or “Coding of Moving Pictures and Associated Audio for Digital Storage Media at Up to About 1.5 Mbit/s”

VHS MPEG-1 Suite ISO IEC 11172

Video compression is carried out by several standards for delivery and display formats. The initial standard in the mid-Eighties, H.120, basically flopped, so the ITU-T VCEG (Video Coding Expert Group) was formed to improve upon it. MPEG (Moving Picture Experts Group) formed to find a way to incorporate codecs for broadcast, and, even today, MPEG and VCEG work side by side, with the former specializing in broadcast and the latter focusing on telecommunications.

In 1988, VCEG created H.261. Around the same time, JPEG (Joint Photographic Experts Group) had grown into a popular codec for images. So, MPEG adopted H.261 and JPEG together, forming a suite. This first suite is known as MPEG-1. MPEG-1 is limited to 1.5 Mbps, 4:2:0, and stereo audio only. It has a low bit rate and small file sizes, and it is compatible with most media players. However, MPEG-1 is known mostly for being the format of VHS tapes.

All MPEG suites have subdivisions. Traditionally, Part One is the “System,” or the file format. Part Two is devoted to the video, and Part Three is the audio. These parts are specified in the ISO/IEC 11172 series of international standards, which are developed by ISO/IEC JTC 1 with MPEG as a working group. This series also consists of Part Four, for conformance testing, as well as a technical report (not a standard), Part Five, for software simulation.

Most people are likely familiar with Layer III of the audio (MPEG-1 Part Three Layer III), which is called MP3.

The ISO/IEC 11172 series is listed below. Please note that some of these documents have corrigenda, which fix editorial errors with active editions.

ISO/IEC 11172-1:1993 – Information technology – Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s – Part 1: Systems

This standard has two corrigenda documents: ISO/IEC 11172-1/Cor1:1996 and Cor2:1999.

ISO/IEC 11172-2:1993 – Information technology – Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s – Part 2: Video

This standard has four corrigenda documents: ISO/IEC 11172-2/Cor1:1996, Cor2:1999, Cor3:2003, and Cor4:2006.

ISO/IEC 11172-3:1993 – Information technology – Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s – Part 3: Audio

This standard has one corrigenda document: ISO/IEC 11172-3/Cor1:1996.

ISO/IEC 11172-4:1995 – Information technology – Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s – Part 4: Conformance testing

This standard has one corrigenda document: ISO/IEC 11172-4/Cor1:2007.

ISO/IEC TR 11172-5:1998 – Information technology – Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s – Part 5: Software simulation

This technical report has one corrigenda document: ISO/IEC TR 11172-5/Cor1:2007.

While MPEG-1 is highly compatible, it suffers from a lower quality and having audio compression limited to only two channels. It is also incompatible with videos taken in high resolution and supports only one color space. However, there is one blaring fact that has made the MPEG-1 suite long obsolete: it was the standard for VHS video quality.

The MPEG-2 suite was introduced in the mid-nineties and it later become the DVD format. Since this time, however, the ISO/IEC 11172 standards for MPEG-1 have remained active, being reaffirmed instead of revised, and have been adopted by INCITS (InterNational Committee for Information Technology Standards) as American National Standards (i.e. Part One is also known as INCITS/ISO/IEC 11172-1:1993[R2013]).

You can read more about MPEG-2 suite and its series of international standards in our post on ISO/IEC 13818 Specifications for MPEG-2, or “Generic Coding of Moving Pictures and Associated Audio Information.”

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