Applies to

Studio

Origin

Audirvāna Remote

Operating System

macOS

Windows

Linux

The Audio Scan uses a unique algorithm to analyze and reveal the actual resolution of a track and check if it matches the audio quality featured in the file metadata. It has been developed in partnership with Ircam Amplify, the business entity of the research lab IRCAM (Institute for Research and Coordination of Acoustics and Music), founded by Pierre Boulez.

Audio Scan explanations

In this article:

• The frequency response graph 
• The results window 
• Explanation of each result

The frequency response graph 

The graph displays the frequency response of the audio track, i.e., the average loudness (dB) in the recording for each frequency (kHz). Loudness is expressed in a negative dB (logarithmic) scale vs. max nominal value =1.

Low frequencies usually have the highest energy level across the frequency range. Thus, the graph usually shows a descending slope from left to right.

A CD format audio track is contained in a darker grey area: on the right, the maximum frequencies captured in the recording are limited to around 22kHz. Below the smaller values, you can record with 16 bits, defining the maximum dynamic range. Because it is an average value, the curve can go below the limit.

Now, if we play and scan a HiRes file, we can see it is contained in a larger, lighter grey area for 88,2 or 96 kHz / 24-bit recordings. The next area is for recordings with even higher sampling rates up to 192 kHz.

The results window 

Below is the quality detected by Audio Scan. If it matches the expected quality, it appears in purple with a 'check' sign next to it. Let's say it is a green light, meaning everything seems OK, and you can confirm it visually with the graph.

Below is the bit depth used in the audio file, followed by the bandwidth. The channel configuration and the absence of DC issues are also checked.

Note: The Audio Scan algorithm is not capable to confirm matching for sampling rates above 192kHz, DSD format and multichannel tracks, and has only access the first unfolding of MQA files. 

Explanation of each result

• Detected quality can be:
  • MP3:  lossy compression is involved with equivalent resolution in kb/s 
  • Not HD: bit-depth is below 16 bits 
  • CD quality (Redbook): 16 bits and 44.1 KHz/48kHz match and with stereo channels
  • SemiHiRe: the audio material within the mix partially comprises CD quality (e.g., 16-bit 44.1/48kHz) tracks and other HiRes material. 
    This is typical of the early 80s digital productions, or more recently, with low-quality samples included in urban music. They show accurate information throughout the audio spectrum. Still, a clear breaking point around 22 kHz suggests that part of the audio material in the mix was not native high resolution but instead CD quality.
  • HiRes: Bit depth equals or exceeds 24 bits with a stereo channel.
    
    
• Why there is or there is not a match:
  • Bit depth: Analyses the actual bit resolution of the audio file.
  • Bandwidth: Returns the actual frequency extension of the track. A note indicates if it has been upsampled.
  • Channels: This checker checks the integrity of the audio file's channel content. It looks for the following potential issues: Silence if one channel is silenced, Mono if both channels are the same, and out-of-phase if the channels are inverted.
    
  • DC Issues: This means a direct current issue, as opposed to AC (alternative current), as in the famous band AC/DC.
    DC, in this case, means a constant current value. Usually, the musical sinusoidal signal goes above and below zero, so it is more like an AC signal. When a constant is detected, it is like the zero has shifted slightly up or down by a constant value (as the constant in a linear equation). This is typical in old analog recordings that have been digitalized. If that value is significant, it could force the speaker's position slightly toward the front or back.
    In some cases, it can damage the speaker. It is unlikely that they are tracks from TIDAL or ripped CDs. I assume it simply indicates that there is a doubt about the fact this is a proper “native” HD digital recording since the presence of DC is typical of digitalized analog recording.

Note: If you have recently subscribed to Audirvāna Studio and get a error when trying to scan a track, please read this article.

VIDEO to know more about the Audio Scan in Audirvāna: