PCM
Type of format | Uncompressed lossless audio format | |
---|---|---|
First released | 1938 | |
Modern version | 1982 (CD), 1991 (WAVE) | |
Designed by | Alec Reeves | |
Compression Type | CBR | Bitrate | 27.648 Mbit/s (3.456 MB memory) |
Channels | 8 | |
Bits | 16, 20, 24 | |
Sample | 8 Channels (48 kHz, 96 kHz), 6 Channels (192 kHz) | |
Filename extension | .wav
| |
Open Format? | Yes | |
Free Format?[1] | Yes | |
Magic Number | Wave: RIFF....WAVEfmt
| |
Movie and Music soundtracks that use PCM audio usually store it in the WAVE file format. It is under the .wav
extension name, which is
located inside the m2ts container. Waveform Audio File Format (WAVE)
was created in 1991 by Microsoft and IBM as a standard for storing
uncompressed bitstream audio. It is natively coded in little-endian byte
order. WAV is based on the Resource Interchange File Format (RIFF)
bitstream format method for storing data in chunks. A RIFF file is a
tagged file format and all WAV files use a RIFF tree structure:
File Root
│
└─ RIFF:WAVE - RIFF Wave header
├─ fmt - Wave format chunk
└─ data - Waveform data chunk
WAV's magic number is 52 49 46 46 xx xx xx xx 57 41 56 45 66 6D 74 20 " RIFF....WAVEfmt".
Another
advantage is that it's an open format, meaning anyone can use the codec
without restrictions or paying royalties. However, one disadvantage is
that it takes up a lot of space because it's uncompressed. Early BD
releases used PCM for movie titles as it's primarily audiotrack, but now
major studios often use DTS and Dolby to conserve space and better compression.
But, PCM is still used for Pure Audio BD music albums for the niche
audiophile market and movies/TV shows from boutique labels.
Interactive Audio
BD uses PCM-based interactive audio for real-time interactive sound effects, usually for menus or video games.
See: Interactive Audio
Auro-3D Extension
Auro-3D is an immersive audio codec that serves as an extension of PCM by adding additional height channels and additional metadata. It is backwards compatible with standard PCM and audio equipment.
See: Auro-3D
Footnotes
Links
- PCM description on MultimediaWiki
- Archive Team's page of PCM
- WAV (Applications) – List of applications known to use WAV
WAV Specifications
- Format spec
- File format info
- Another file format info text file
- MSDN: Registered FOURCC Codes and WAVE Formats
- WAVE and AVI Codec Registries (Historic Registry)
WAV Metaformat files
- Synalysis grammar file (for Hexinator / Synalize It!; more details)
WAV Sample files
External links
Author(s) : Æ Firestone
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