Digital audio

Draft

Audio file formats

“It is important to distinguish between a file format and a codec. A codec performs the encoding and decoding of the raw audio data while the data itself is stored in a file with a specific audio file format” (Wikipedia).

Formats

Example of lossy compression

• MP3 (MPEG Layer-3)
• OGG (most often with Vorbis codec, therefore know as OGG-Vorbis)

Lossless examples

• WMA (Microsoft)
• WAV mostly for Windows PCs. Can use several compression codecs (most often uncompressed PCM as in standard audio CDs)
• AIFF (The Mac equivalent of WAV)

Overview of CD Formats

Most of these are called CD Rainbow Books (referring to the color of the specification documents)

1. Red Book (CD Digital Audio). The basic standard for all CDs, including music CDs. Digital audio encoding: 2-channel signed 16-bit PCM sampled at 44,100 Hz.
2. Yellow Book (CD-ROM and CD-ROM XA). CDs for data (software)
3. Orange Book (CD-R and CD-RW). Recordable CDs
4. White Book (Video CD). CDs with video content that plays in most DVD players.
5. Blue Book (Enhanced CD, CD+G, and CD-Plus). Music CDs with extra features like videos or photos.
6. Beige Book (Photo CD). Kodak's format for storing photos on a CD.
7. Green Book (CD-i). Rarely used. CD-Interactive contains educational material and games.
8. Purple Book (DDCD) hold more storage than CDs and require a special reader, not popular
9. High Density CD (HDCD), an alternative to DDCD, not popular
10. Scarlet Book (SACD). Super Audio CDs uses Direct Stream Digital (DSD) recording, a proprietary Sony/Philips format. Quality is superb but needs a special player to work. There are three separate versions, one of which includes a red-book layer so that music will also play on an old CD player.
11. DVD-Audio (DVD-A) is a Digital Versatile Disc (DVD) format that is specifically designed to hold high-quality audio data. An alternative to SA-CD

Links

Overviews

• Digital Audio (Wikipedia).

• High fidelity (Wikipedia)

• WikiRecording.org A wiki on recording.

Information about audio file and compression formats

• Description of popular audio formats (Streaming media FAQ)

• Audio file format

• Wave File Compression Codecs Compared

• WAV (Wikipedia).

Information about CD standards

• Red Book (audio CD standard) (Wikipedia)

• DVD-Audio (Wikipedia)

• SA-CD FAQ. Quote: This FAQ aims to be the most comprehensive concerning SA-CD on the web, but also independent, unbiased, practical and readable

• Wikipedia Super Audio CD

Other

• ProAudio Review. Online journal with reviews of products (some open access)
• DVD Primer, at DVDForum, 2000