User:LordSputnik/Recording Style Guidelines (Version 1)
This proposal is designed to improve the guidelines on merging recordings. It is felt that the current guidelines are too vague, and that they don't cover all cases where recordings might be merged. This proposal seeks to expand these guidelines and make them clearer.
Edit http://musicbrainz.org/doc/Style/Recording to change the section "What should and shouldn't be merged together?" to the following.
A recording is intended to represent a unique audio source. This means that generally, two releases should only share recordings if the audio source used to create them was the same. An audio source is considered unique as soon as any changes make it different from a previous source.
- If multiple performances of a single work are recorded and released then each performance is a separate audio source, and each released performance should have a separate recording.
- If there are multiple releases of a single live performance and each was recorded by a different device, each device is a separate source and each release should have its own set of recordings.
- If a release was originally recorded in analogue and released only on vinyl, any CD or digital releases should use separate recordings. The original analogue source was changed when it was converted from analogue to digital.
- If a release is recorded digitally and released in both analogue and digital formats then the releases may share recordings. The audio sources for both releases are the digital recordings.
- If two versions of a release are mastered in audibly different ways, then the source has been changed for each mastering, and each release should have its own set of separate recordings.
- If a release is remastered from an earlier release, all the tracks on the new release should be new recordings. The source was changed when the recording was remastered. If another remaster is made, then the source has changed again, and another set of recordings should be made.
- If a recording is edited or remixed, the new version should have a separate recording. The exception to this rule is for changes only to the fade-in or fade-out of a track, where a new recording should only be used when the difference in length is greater than 10 seconds.
In addition to these cases and the general guidelines, recordings with multiple, visibly different AcoustID fingerprints should not be merged. Instead, the recordings and AcoustIDs should be examined for correctness.
In theory, recordings which have different sources should be assigned different ISRCs. In practice however, this doesn’t always happen. Recordings with different ISRCs should be examined closely to determine whether they are actually different. Similarly, recordings with the same ISRCs may in fact be different, so care should be taken before merging them.
point 5 Death Magnetic by Metallica was noticeably different on the Guitar Hero 3 release from the album itself. And the record was noticeably different from the CD.