What is MPG

MPG, namely MPEG-1, is a world-famous standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to 1.5 Mbit/s without excessive quality loss, making video CDs, digital cable/satellite TV and digital audio broadcasting (DAB) possible. Today, MPEG-1 has become the most widely compatible lossy audio/video format in the world, and is widely used in a large number of products and technologies. Perhaps the best-known part of the MPEG-1 standard is the MP3 audio format it introduced.

The MPEG-1 standard is published as ISO/IEC 11172 – Information technology—coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbit/s. The standard consists of the following five parts:

  1. Systems (storage and synchronization of video, audio, and other data together)
  2. Video (compressed video content)
  3. Audio (compressed audio content)
  4. Conformance testing (testing the correctness of implementations of the standard)
  5. Reference software (example software showing how to encode and decode according to the standard)

 

File Extension

.mpg is one of a number of file extensions for MPEG-1 or MPEG-2 audio and video compression. .mp3 is the most common extension for files containing MPEG-1 Layer 3 audio. An MP3 file is typically an uncontained stream of raw audio; the conventional way to tag MP3 files is by writing data to “garbage” segments of each frame, which preserve the media information but are discarded by the player.

 

Resolution/Bitrate

MPEG-1 supports resolutions up to 4095×4095 (12-bits), and bitrates up to 100 Mbit/s. MPEG-1 videos are most commonly seen using Source Input Format (SIF) resolution: 352×240, 352×288, or 320×240. These low resolutions, combined with a bitrate less than 1.5 Mbit/s, make up what is known as a constrained parameters bitstream (CPB), later renamed the “Low Level” (LL) profile in MPEG-2. This is the minimum video specifications any decoder should be able to handle, to be considered MPEG-1 compliant. This was selected to provide a good balance between quality and performance, allowing the use of reasonably inexpensive hardware of the time.

 

Applications

  1. Most popular software for video playback includes MPEG-1 decoding, in addition to any other supported formats.
  2. The popularity of MP3 audio has established a massive installed base of hardware that can play back MPEG-1 Audio (all three layers).
  3. “Virtually all digital audio devices” can play back MPEG-1 Audio. Many millions have been sold to-date.
  4. MPEG-1 is the exclusive video and audio format used on Green Book CD-i, the first consumer digital video format, and on Video CD (VCD), still a very popular format around the world.
  5. The DVD-Video standard originally required MPEG-1 Layer II audio for PAL countries, but was changed to allow AC-3/Dolby Digital-only discs. MPEG-1 Layer II audio is still allowed on DVDs, although newer extensions to the format, like MPEG Multichannel, are rarely supported.
  6. Most DVD players also support Video CD and MP3 CD playback, which use MPEG-1.
  7. The international Digital Video Broadcasting (DVB) standard primarily uses MPEG-1 Layer II audio, and MPEG-2 video.
  8. The international Digital Audio Broadcasting (DAB) standard uses MPEG-1 Layer II audio exclusively, due to MP2′s especially high quality, modest decoder performance requirements, and tolerance of errors.

 

Related Guides and Tutorials for MPG Format

MPG to AVI – convert MPG videos to AVI on Win/Mac with high quality

MPEG to AVI – convert MPEG to AVI without quality loss on Win/Mac

MPG to DVD – convert and burn MPG video files to DVD easily and quickly