1     Functions

2     Reference Model

3     I/O data of AI Workflow

4     Functions of AI Modules

5     I/O Data of AI Modules

6     AIW, AIMs, and JSON Metadata

1      Functions

Preservation of audio assets recorded on analogue media is an important activity for a variety of application domains, in particular cultural heritage. Preservation goes beyond mere A/D conver­sion. For instance, the magnetic tape of an open reel may hold important information: it can carry annotations (by the composer or by the technicians) or it can include multiple splices and/or display several types of Irregularities (e.g., corruptions of the carrier, tape of different colour or chemical composition). This information shall be preserved for a correct playback. Nevertheless, some errors can occur during the digitisation as well as the digitisation could be partial because of the corruption of the carrier. These errors shall be restored to make the content listenable. The ARP Use Case (see 5.1.5) concerns the creation of a digital copy of the digitized audio of open reel mag­netic tapes for long-term preservation and of an access copy (restored, if necessary) for correct playback of the digitized recording.

In this Audio Recording Preservation Use Case, two files are fed into a preservation system:

The following is not required:

The output of the restoration process is composed by:

  1. Preservation Master Files.
  2. Access Copy Files.

2      Reference Model

Figure 3 depicts the Audio Recording Preservation Reference Model.

Figure 3 – Audio Recording Preservation Reference Model

The sequence of operations of the Audio Recording Preservation unfolds as follows:

3      I/O data of AI Workflow

Table 6 gives the input and output data of Audio Recording Preservation.

Table 6I/O data of Audio Recording Preservation

Input Comments
Preservation Audio File A Preservation Audio File obtained by digitising the analogue tape audio recording composed of music, soundscape or speech read from a magnetic tape.
Preservation Audio-Visual File A Preservation Audio-Visual File produced by a camera pointed to the playback head of the magnetic tape recorder.
Output data Comments
Preservation Master Files Set of files providing the information stored in an audio tape recording without any restoration. As soon as the original analogue recordings is no more accessible, it becomes the new item for long-term preservation.
Access Copy Files Set of Audio Files derived from the Preservation Audio File, where potential speed, equalisation or reading backwards errors that occurred in the digitisation process have been corrected.

4      Functions of AI Modules

The AIMs required by this Use Case are described in Table 7.

Table 7 – Functions of AI Modules of Audio Recording Preservation

AIM Function
Audio Analysis for Preservation 1. At the start, it calculates the offset between Preservation Audio and the Audio of the Preservation Audio-Visual File.
2. Sends Audio Irregularity File to and receives Video Irregularity Files from Video Analysis for Preservation.
3. Extracts the Audio Files corresponding to the Irregularities identified in both Irregularity Files.
4. Sends the Irregularity merged from the Audio and Video Irregularity Files to Tape Irregularity Classification with the corresponding Audio Files.
Video Analysis for Preservation 1. Detects and enters the Video Irregularities of the Preservation Audio-Visual File in the Video Irregularity File.
2. Sends Video Irregularity File to and receives Audio Irregularity Files from Audio Analysis for Preservation.
3. Extracts the Images corresponding to the Irregularities of both Irregularity Files.
4. Sends the Irregularity merged from the Audio and Video Irregularity Files to Tape Irregularity Classification with the corresponding Video Files.
Tape Irregularities Classification 1. Receives Irregularity File (Audio) and Audio Files from Audio Analysis for Preservation.
2. Receives Irregularity File (Video) and Irregularity Images from Video Analysis for Preservation.
3. Classifies and selects the relevant Irregularities of the Preservation Audio-Visual File and Preservation Audio File.
4. Sends the Irregularity File related to the selected Irregularities to Tape Audio Restoration.
5. Sends the Irregularity Files related to the selected Irregularities and the corresponding Irregularity Images to Packaging for Audio Recording.
Tape Audio Restoration 1. Detects and corrects speed, equalisation and reading backwards errors in Preservation Audio File.
2. Sends Restored Audio Files and Editing List to Packaging for Audio Preservation
Packaging for Audio Recording Produces Preservation Master Files and Access Copy Files.

5      I/O Data of AI Modules

Table 8 – CAE-ARP AIMs and their data

AIM Input Data Output Data
Audio Analysis for Preservation Preservation Audio File

Preservation Audio-Visual File

Irregularity File

Audio Files

Audio Irregularity File

Video Analysis for Preservation Preservation Audio-Visual File

Audio Irregularity File

Video Irregularity File

Irregularity Images

Tape Irregularities Classification Irregularity Audio Files

Audio Irregularity File

Irregularity Images

Video Irregularity File

 

Irregularity File

Irregularity Images

Tape Audio Restoration Irregularity File

Preservation Audio File

Editing List

Restored Audio Files

Packaging for Audio Preservation Preservation Audio File

Restored Audio Files

Editing List

Irregularity File

Irregularity Images

Preservation Audio-Visual File

Access Copy Files

Preservation Master Files

6      AIW, AIMs, and JSON Metadata

Table 9 – Acronyms and URs of JSON Metadata

AIW AIMs Name JSON
CAE-ARP Audio Recording Preservation File
CAE-AAP Audio Analysis for Preservation File
CAE-VAP Video Analysis for Preservation File
CAE-TIC Tape Irregularity Classification File
CAE-TAR Tape Audio Restoration File
CAE-PAP Packaging for Audio Preservation File