PQ-Codes

Savannah Berry - Silent Night Without You

PQ codes are the first 2 of 8 sub-channel information encoded on a 'Red Book' CD. Each subcode channel is designated a letter P through W.

The P channel gives simple instructions to the player about track locations. Sometimes it is used by lower cost players due to its simplicity. More sophisticated CD players will ignore the P channel and go straight to the Q channel for more detailed information. The Q channel holds all the non-audio information on a typical Audio CD. Several important player control codes like track number, track time, disc time, serial number, MCN (like a barcode), ISRC, copyright info, etc. . . CD Text info is also embedded in this channel. Channels R through W were reserved for expansion of the CD format, but have not come into use.

ISWC

The International Standard Musical Work Code, or ISWC, is a unique identifier for musical works. Like the ISRC is for recordings and the ISNI is for people, the ISWC helps identify and disambiguate musical works. Along with being a unique identifier, the ISWC is also permanent and an internationally recognized ISO reference number for the identification of musical works.

International Standard Name Identifier is new metadata to resolve name ambiguity for contributors to creative works. This number can define a person, like a writer, artist, performer, producer, etc., or it can define an organization, like publishers, studios, aggregators, etc..

ISRC In WAV Files

The Music Producers Guild (MPG) in partnership with the European Broadcast Union (EBU) have now standardized a metadata field for the International Standard Recording Code (ISRC) in wav files! This issue has been a long time overdue, but now finally gained enough traction to make it into a standard. The ISRC can now be embedded in wav files inside the core metadata. This means it will follow the file where ever it goes.

Metadata

wav

ISRC

.cda file format

Often a source of confusion is the .cda file. On a windows computer, when you insert a RedBook Audio CD, the tracks show up as .cda files. One might assume that these are the audio files on the disc because they are the only items that show up in the explorer window. . . that would be wrong. The .cda files are merely placeholders pointing to a place on the CD that the song starts. Think of them as what windows calls a 'shortcut'.

Jitter

Jitter is a time-based signal error. Often misunderstood, this problem can range from subtle and nearly inaudible to loud and distracting. Jitter can reduce low-level resolution (add noise) and add distortion.