© República Argentina

DJ Matías

Collector, connoisseur and DJ of Argentine tango music

Audio processing

After having invested a lot of passion, time and financial resources to build up a comprehensive collection of tango music, it is natural that only the most advanced techniques and the best equipment are used to transfer the audio data to the computer system.

For audio data management, a business notebook running under Windows 7 is employed. A studio-grade external drive (Plextor PX-W1210A modified by AQVOX) is used for CD ripping. This professional drive allows the audio grabber software to employ:

The external drive is mechanically decoupled from the computer and connected via an high-definition USB cable specifically assembled by AQVOX to provide effective jitter suppression. In order to eliminate potential read errors induced by residual mechanical vibrations of the spinning motor, a small freeware program called CD-Bremse is used to slow down the spindle velocity to 1x speed. Thereby, the drive is completely silent during its operation.

The software package EAC (Exact Audio Copy) is employed for ripping the audio data in the highest secure mode. The read and write offset of the external drive are determined using reference CDs and stored in a local database for offset compensation. During the ripping process, the following statistical operations are performed for each audio track:

  • Monitoring of the C2 error pointer reported by the external CD drive;
  • Calculation of the CRC (Cyclic Redundancy Check) checksum;
  • Online cross-comparison to the corresponding entry in the AcurateRip internet database.

The novel AcurateRip V2 model is employed to avoid false negative results which may be caused by offset displacements in new pressings of re-released CDs. Moreover, the audio data are compared to the independent Cuetools internet database for cross-verification. If a discrepancy occurs, the affected CD sector is re-read up to 82 times at the highest secure mode settings using a statistical model. The CRC checksums obtained by the ripping procedure are finally submitted to both the AcurateRip and the Cuetools online database for subsequent public use.

The audio data are stored in the lossless FLAC (Free Lossless Audio Codec) file format using the highest compression level. A variety of advanced FLAC encoding options are employed, e.g.

The audio editor software Audacity is employed for processing of the audio data, i.e.

  • to trim the silence at the beginning of the track and/or
  • to add a fair amount of silence at the end of the track (if necessary).

The corrected audio data is also stored in the FLAC format under a new file name together with a short description of the nature of the data processing performed. The original file is preserved for archival purposes.

Since the audio data are stored in the lossless FLAC format, both the encoding and the decoding process can be repeated as often as desired without any degradation of the audio quality – in contrast to popular lossy compression formats like:

  • MP3 (Moving Picture Experts Group Audio Layer III);
  • AAC (Advanced Audio Coding);
  • WMA (Windows Media Audio).

Essential reading

Digital-to-analog conversion