Information about Mpeg 1 Audio Layer I
Not to be confused with MPEG-1.
MPEG-1 Audio Layer I, commonly abbreviated to MP1, is one of three audio codecs included in the MPEG-1 standard. While supported by most media players, the codec is considered largely outdated, and replaced by MP2 or MP3.
For files only containing MP1 audio, the file extension .mp1 is used.
MP1 uses a comparatively simple sub-band coding, using 32 sub-bands.[1]
MPEG-1 layer I was also used by the Digital Compact Cassette format, in the form of the PASC audio compression codec. Because of the need of a steady stream of frames per second on a tape-based medium, PASC uses the rarely used (and under-documented) padding bit in the MPEG header to indicate that a frame was padded with 32 extra 0-bits (four 0-bytes) to change a short 416-byte frame into 420 bytes. The varying frame size only occurs when a 44.1kHz 16 bits stereo audio signal is encoded at 384 kilobits per second, because the bitrate of the uncompressed signal is not an exact multiple of the bitrate of the compressed bit stream.
References
External links
- http://www.otolith.com/otolith/olt/sbc.html A description of sub-band coding, including an overview of the MP1 codec.
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 (VCD) format and less commonly by the DVD-Video format.
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- codec, see Codec (disambiguation).
A codec is a device or program capable of performing encoding and decoding on a digital data stream or signal. The word codec may be a combination of any of the following: 'Compressor-Dec
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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 (VCD) format and less commonly by the DVD-Video format.
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MPEG-1 Audio Layer 2
File extension:
MIME type:
Type of format: Audio
MPEG-1 Audio Layer II (MP2, sometimes Musicam) is an audio codec defined by ISO/IEC 11172-3.
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File extension:
.mp2MIME type:
audio/mpegType of format: Audio
MPEG-1 Audio Layer II (MP2, sometimes Musicam) is an audio codec defined by ISO/IEC 11172-3.
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MPEG-1 Audio Layer 3
File extension:
MIME type:
Type of format: Audio MPEG-1 Audio Layer 3, more commonly referred to as MP3, is an audio encoding format.
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File extension:
.mp3MIME type:
audio/mpegType of format: Audio MPEG-1 Audio Layer 3, more commonly referred to as MP3, is an audio encoding format.
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Sub-band coding (SBC) is any form of transform coding that breaks a signal into a number of different frequency bands and encodes each one independently. This decomposition is often the first step in data compression for audio and video signals.
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Digital Compact Cassette
Media type: Magnetic tape
Encoding: Precision Adaptive Sub-band Coding
Capacity: 105 minutes
Write mechanism: multi-track stationary head
Developed by: Philips & Matsushita
Usage: audio
Extended from: Compact cassette
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Media type: Magnetic tape
Encoding: Precision Adaptive Sub-band Coding
Capacity: 105 minutes
Write mechanism: multi-track stationary head
Developed by: Philips & Matsushita
Usage: audio
Extended from: Compact cassette
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