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Audio Transfer Control

For all types of audio carriers, some general as well as carrier specific quality control measures are built into NOA's digitization applications. The results of them are visible during as well as after recording directly within the appropriate applications and may also be forwarded alongside with the digitized material to a subsequent QC step within the workflow or to be saved with the essence file on a MAM system.

The ability of NOA's audio transfer control features to immediately notify the operator on transfer errors (e.g. an interstital error detected by BitProof or a shift in Azimuth during a tape recording) saves valuable time, as operators may instantly react to changes of those parameters. In the context of an industrial digitization facility, where quality control may be conducted by QC operators in a subsequent step, clear error markers and traces, which are easy and quick to identify, speed up the process of quality control.

BitProof - The end to interstitial errors

Two thirds of surveyed archives report experience with interstitial errors, which typically show themselves as distinct clicks, buffer swaps or mutes distributed randomly in the final audio recording. The source was identified to be failures in the chain between AD converters to the writing of the file on the hard disk. 

Being in the position to not only provide software but also the appropriate hardware interfaces for audio digitization, NOA was able to introduce BitProof™ as a reliable and process effective means of detection of interstitial errors.

BitProofBitProof is the method of creating permanently a CRC checksum in the DSP of the N7000c audio interface and separately transmitting it to the DAW, where the recording software NOARecord creates another CRC when writing the file to the hard disk, which is then compared to the original check sum created at the DSP. Erroneous checksums stop the recording immediately allowing for path error investigation.

BitProof …

  1. will notify of interstitial errors immediately
  2. comes at no additional cost or complexity
  3. will keep your digitization process effective
  4. is getting more and more necessary as AoIP becomes more popular
Algorithmic Traces

Diagnostic_TracesAlgorithmic traces illustrate a complete analysis of events along the recorded audio file. Traces, as well as all quality related events, are directly linked to the audio file and behave in the NOA players as zoom-able and linked information to give – also in an asynchronous parallel transfer – an immediate overview of the quality of the audio file no matter which carrier has been ingested. This quality-related information – collected at the moment of ingest – is then stored in the Pico, jobDB or mediARC process environments, allowing for both a centralized quality assessment and export from the workflow system to mediARC or to a foreign MAM system.

Algorithmic trace NOARecord MediaLector CDLector File Ingest
Bandwidth L/R (x10 kHz)  ✔
Correlation (-1/+1) ✔  ✔   ✔ ✔ 
Azimuth (degree shift @10 kHz) ✔  ✔   
RMS level L/R (dBfs) ✔  ✔   ✔ ✔ 
Peak level L/R (dBfs) ✔  ✔   ✔ ✔ 
Noise L/R (dBfs) ✔  ✔    ✔ 
BLER L/R traces ✔  ✔     

     

BLER

When ingesting DAT cassettes, characteristic BLER events are displayed both within a marker list as well as a clearly visible trace. Within only a few seconds, quality check operators are able to identify faulty transfers.

Example of a faulty transfer, where transfer errors are identifiable as obvious accumulations of BLER events:

BLER

Event related parameters and Statistics

During digitization of audio carriers, event related parameters and statistical data are collected which are accessible during and after recording within the appropriate recording software (NOARecord, MediaLector, or CDLector) as well as exportable within an .xml file. Apart from standard audio parameters (e.g. clicks, digital over etc.), also carrier specific information is logged.

 

Event related parameters NOARecord MediaLector CDLector File Ingest
Clicks L/R  ✔
Digital overload on A/D Converter L/R      
Digital overload   ✔ 
Azimuth Overs (Threshold)      
Mute L/R   ✔ 
Tape Condition (via N6035A)      
Digital mutes *)      
Digital interpolations *)      
Physical read problems *)      
Sample rate changes *)      
Subcode index *)      
Start, stop, end ID  ✔    
CD-Read errors (E32 indication)      

 *) with replayer models 7040 and R500

Overall statistics NOARecord MediaLector CDLector File Ingest
Number of Mutes L/R  ✔
Number of Clicks L/R ✔ 
Mean Noise L/R ✔ 
Mean RMS L/R ✔ 
Mean Bandwidth L/R ✔    ✔ 
Max Peak L/R at Position ✔    ✔ 
Mean Correlation ✔  ✔  ✔ 
Tape Light Barrier

Tape Light BarrierUnique analysis tool for tape recordings that uses advanced transparency analysis to recognize different colors and scratches, as well as magneticlayer loss.

Tape Light Barrier connects directly to the N7000c audio hardware. The gathered timecode information from yellow tape allows for semi automated tracksplitting (e.g. of masters).

Recognition of:

  • Red tape (38 cm/s, mono)
  • Red white tape (38 cm/s, stereo)
  • Blue tape (19 cm/s, mono)
  • Blue white tape (19 cm/s, stereo)
  • Splices
  • Magnetic layer loss

 





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