Looking into Tidal artifacts (1)


Tidal (wiki) offers unlimited online and offline access to their music library. If you use the Tidal HiFi subscription it promises:

"Lossless High Fidelity sound quality." (source: tidal.com)

I have come across a number of tracks where I believe the sound quality is substandard. That will be the topic of this web page and this investigation.


Qobuz (wiki) offers similar services compared to Tidal. If you are willing to pay for their Sublime+ subscription, they promise:

"The best music subscription in the world: unlimited Hi-Res streaming, Hi-Res downloads at a special price" (source: qobuz.com)

What are those artifacts? What do I hear?

With the majority of Pop and Jazz it is hard to notice anything wrong, and only with a small number of tracks (often Classical music) the artifacts become noticeable. Most likely the audio source material is being fingerprinted before it is being sent over in FLAC format.

The most obvious artifacts are a sort of "fluttering" in the mid section of instruments like pipe organs, clarinet, sax, especially when the instrument is supposed to produce a stable long note. It sounds as if someone is randomly (quickly) changing the volume of that instrument, causing fluttering in the sound. As if Count Basie's sax contains ping pong balls that bounce around. As if the pipe organ is broken. The quick changes in volume are not comparable to for instance a leslie box. The volume change is more like on/off instantaneously.

Also the artificats are most obvious when the other instruments are temporary silent. In a normal piece of music where there is drum, singing, guitar, I would not be able to point my finger are these artifacts. Eventhough I suspect they are still there, and that they are still having a negative effect on the sound quality.

What do we know about fingerprinting?

First of all, we know that audio fingerprinting (a.k.a. audio watermarking) does exist:

1. "Media identification using acoustic fingerprints can be used to monitor the use of specific musical works and performances on radio broadcast, records, CDs and peer-to-peer networks. This identification has been used in copyright compliance, licensing, and other monetization schemes." Source: acrcloud.com.

2. "Collusion-resistant fingerprinting paradigm seems to be a practical solution to the piracy problem as it allows media owners to detect any unauthorized copy and trace it back to the dishonest users." Source: www.ncbi.nlm.nih.gov.

3. "Proprietary, patented, industrial-grade audio watermarking engine. Easy file authentication and back-tracing of leaks via watermark retrieval." Source: kvraudio.com

And second, more people have noticed artifacts using streaming services, and use different words to describe what it sounds like:

1. "It sounds like a fluttery warble noise in the midrange. It's most noticeable during big string or choir sections with broad spectral content." Source: mattmontag.com.

2. "On the first song, Modul 36, you can hear this clearly when the piano emerges from the pitch black background and then fades away. Someone described the effect as listening through a ceiling fan?" Source: computeraudiophile.com.

And thirdly, some people have already pin-pointed that the audible artifacts are indeed due to watermarking or fingerprinting by either the streaming service, or the record labels when they deliver their source material:

1. "The watermark scheme modulates the total energy in two different bands, 1khz to 2.3 khz and 2.3 to 3.6 khz. The energy is concentrated in the most perceptually sensitive frequencies because that makes it more difficult to attack or remove without significant audible distortion. The energy is increased or reduced in 0.04 second blocks. The result can be characterized as a fluttering, tremolo sound." mattmontag.com.