MPEG-1 was the first compression standard for audio and video introduced in 1992.
The primary purpose of MPEG-1 is to encode an AV signal to fit a Compact Disc (CD-ROM) at a maximum bitrate of 1.5MBps.
When this is done, you get a Video CD (VCD).
The MPEG-1 compression is optimized to fit the maximum data rates of CD-ROM. That is 1.1Mbps for video and 128kbps for audio (stereo).
CD-ROMs support a data bitrate of up to 1.4Mbps.
Resolution and Refresh Rate
The following resolutions and refresh rates are applicable when MPEG-1 compression is used in CD-ROMs.
For NTSC, a resolution of 352 x 240 active pixels is supported with a refresh rate of 29.97 frames per second.
For PAL or SECAM the resolution is 352 x 288 active pixels and the refresh rate is 25 frames per second.
These resolutions are optimized for TV screens supporting the 4:3 aspect ratio.
Other Uses of MPEG-1 Compression
Apart from VCDs, MPEG-1 is also used to compress and transmit video over the Internet in low-bandwidth situations.
Advantages of MPEG-1 Compression
You can play MPEG-1 files in just about any media player. You don’t need a special software program to open an MPEG-1 file.
Also, it doesn’t take much computing power to open an MPEG-1 file. As such, you can play MPEG-1 files on older computers with low processing speed and RAM.
What kind of video quality can you expect from MPEG-1 compression?
You get video around VHS quality.
MPEG-1 Layer 2
MPEG-1 Layer 2 also known as MP2 is another part of the MPEG-1 compression standard.
The compression standard is meant for audio.
The compression employed by MP2 is of the lossy type.
This means audio data from the original file is removed to shrink the file size.
Of course, this would lead to quality loss. But then the drop in quality is almost unnoticeable by the human ear.
Read more about MPEG1- Layer II (MP2).
MPEG-1 Layer 3
MPEG-1 Layer III is popularly known as MP3. MP3 can be said to be the most popular among the MPEG-1 formats.
MPEG-1 Layer 3 is a lossy compression format. Audio quality is lost during compression.
However, in the case of MP3, the quality loss isn’t noticeable to the human ear.
MP3 is popular because it offers good audio fidelity (how accurately a copy reproduces its source) for a smaller file size.
Technically, MPEG-1 Layer III offers better compression efficiency than Layer 1 (MP1) and Layer 2 (MP2).
Support for single-channel, dual-channel, stereo, and joint stereo audio is available.
It boasts a compression factor of about 12. In other words, a 12 MB file can be reduced to 1 MB.
That makes MP3 a popular choice for audio streaming and downloadable audio files over the Internet.
There are dedicated MP3 players. It is a format supported across a wide range of devices including smartphones, tablets, computers, HDTV, TV boxes, and more.
Current Uses of MPEG-1
MPEG-1 can be considered outdated in the current context of digital video. Newer codecs like MPEG-4, H.264, and H.265 are the order of the day. They have better compression efficiency and deliver high-quality video.
However, MPEG-1 is still used in the following environments.
- Legacy equipment like old mobile devices and gaming consoles still uses MPEG-1.
- Some organizations may have stored AV material in the MPEG-1 format for archival purposes.
- MPEG-1 is still used for streaming video in cases of low-bandwidth connections or in areas with poor Internet connections.
- Some educational institutions have educational and research materials stored in the MPEG-1 format.
- Some older mobile devices still have to rely on MPEG-1 to access streaming video. They can’t support newer streaming codecs.
- VCD players can only read MPEG-1 content.
International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC). (1992). ISO/IEC 11172-1: Information technology – Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s – Part 1: Systems. Geneva, Switzerland: ISO/IEC.
Encyclopedia of Multimedia A–Z, 2nd Edition