File specification · revision 4, July 2026

What you get, down to the filename

This page is the contract about files. If a folder we send you does not match what is written here, that is our error and we will redo the delivery at our cost.

Folder shape

26-0431/
  README.txt                  job summary, client, dates, operator initials
  MANIFEST.sha256             one line per file, relative paths
  condition-report.pdf        photographs and inspection phrases
  item-sheets.csv             catalogue fields, one row per side
  masters/
    26-0431-001-A-flat-24-96.wav
    26-0431-001-A-flat-24-96.md5
    26-0431-001-B-flat-24-96.wav
    26-0431-001-B-flat-24-96.md5
  restored/                   present only if restoration was ordered
    26-0431-007-A-rest-24-96.wav
    26-0431-007-A-rest-24-96.log
  access/                     present by default
    26-0431-001-A.flac

Naming

job: two-digit year, hyphen, four-digit counter: 26-0431
item: three digits, in the order items came out of the box
side or pass: A, B, then P2, P3 for extra passes
kind: flat, rest, tc for a timecode track
format tag: bit depth and sample rate, hyphenated: 24-96, 24-192

No spaces, no accented characters, no client names in filenames. Names stay stable across redeliveries, so a reference in your own catalogue does not rot if we send the folder twice.

Audio specification

Defaults. Anything in this table can be changed per job if you say so during intake.
Deliverable	Container	Depth / rate	Channels	Level policy
Preservation master, tape and cassette	BWF (.wav)	24 / 96	as recorded	peak near −6 dBFS, no limiting
Preservation master, wire and lacquer	BWF (.wav)	24 / 192	mono, both groove walls kept separately on request	peak near −6 dBFS
Preservation master, DAT	BWF (.wav)	16 / as written	as recorded	bit-identical, no gain
Restored copy	BWF (.wav)	24 / 96	as master	as master, plus log
Access copy	FLAC level 5	16 / 44.1	as master	−16 LUFS integrated if asked

Quarter-track tapes recorded in both directions arrive as separate files per direction, never interleaved into a four-channel file, because the two directions are different recordings that happen to share a plastic reel.

Metadata we write into the file

BWF files carry a broadcast extension chunk; we fill it rather than leaving it blank:

Field	Content	Example
Description	item, side, source format, speed	26-0431-001 A, 1/4 in quarter-track, 3 3/4 ips
Originator	our lab short name	WIREDRUM
OriginatorReference	job and item	26-0431-001-A
OriginationDate	date of transfer, not of recording	2026-09-24
CodingHistory	deck, preamp, converter, curve	A=ANALOGUE,M=stereo,T=deck-2/IEC1; A=PCM,F=96000,W=24

The date of the recording, where we know it, belongs in the item sheet and the catalogue - not in the origination field, which by definition describes the transfer.

Item sheet columns

item, side, source_format, speed, duration
label_text - transcribed exactly, including misspellings
heard_content - what the audio actually contains, in plain words
spoken_date, spoken_names - only if said aloud on the recording
condition, defects_timecodes, operator, transfer_date

Integrity

Each audio file gets an MD5 beside it, and the whole folder gets a SHA-256 manifest. We verify after writing the drive and again if we ever re-send. The reason for two algorithms is dull: the per-file MD5 is for people with old tools who want a quick check, the manifest is the real one.

Verifying what you received

On any machine with standard tools, change into the job folder and run shasum -a 256 -c MANIFEST.sha256. Every line must say OK. One failing line is worth an email to tech@wiredrum.llc - a drive that fails one file usually fails more later, and we would rather ship you a new one now.

Retention

Masters stay on our array for ninety days after delivery, on two disks in different machines. After ninety days we delete them unless the job sheet says otherwise. Longer retention is free up to a year and must be asked for in writing, because «keep it just in case» in a phone call is not something we can act on.