MPEG-1
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MPEG-1 defines a group of Audio and Video (AV) coding and compression standards agreed upon by MPEG (Moving Picture Experts Group). MPEG-1 video is used by the Video CD format. The output quality at usual VCD bit rates is roughly that of a VHS tape. MPEG-1 audio layer 3 is the full name for the popular audio format MP3. As cheaper and more powerful consumer decoding hardware became available, more advanced formats such as MPEG-2 and MPEG-4 were developed. These newer formats are more complex and require more powerful hardware, but they also achieve greater coding efficiency, i.e., quality per bitrate.
MPEG-1 consists of several "parts", as follows:
- Synchronization and multiplexing of video and audio (MPEG-1 Program Stream).
- Compression codec for non-interlaced video signals.
- Compression codec for perceptual coding of audio signals. The standard defines three "layers," or levels of complexity, of MPEG audio coding.
- # MP1 or MPEG-1 Part 3 Layer 1 (MPEG-1 Audio Layer 1)
- # MP2 or MPEG-1 Part 3 Layer 2 (MPEG-1 Audio Layer 2)
- # MP3 or MPEG-1 Part 3 Layer 3 (MPEG-1 Audio Layer 3)
- Procedures for testing conformance.
- Reference software.
MPEG-1 video
MPEG-1 video was originally designed with a goal of achieving acceptable video quality at 1.5M bit/second data rates and 352x240 resolution. While MPEG-1 applications are often low resolution and low bitrate, the standard allows any resolution less than 4095x4095. Nevertheless, most implementations were designed with the Constrained Parameter Bitstream specification in mind.
At present MPEG-1 is the most compatible format in the MPEG family; it is playable in almost all computers and VCD/DVD players.
One big disadvantage of MPEG-1 video is that it supports only progressive pictures. This deficiency helped prompt development of the more advanced MPEG-2.
See also
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