How many grooves on a vinyl record? Two; one per side, each groove delivering a handful of songs to the listener. If that album is Wire’s Chairs Missing, when played, each song stands as a distinct entity, separated from its neighbour by a one- or two-second gap. Just as the artist intended. But if that record is Pink Floyd’s Animals, when played, each song will flow seamlessly into the next. Again, just as the artist intended. After all, the existence and/or length of gaps between tracks is decided in the mixing/mastering studio.
How many tracks on an audio CD? It might look like many but in reality, it’s one. An audio CD is essentially a single (.wav) data ‘file’. Any track markers (separators) shown on the CD player’s display are virtual, read from a table of contents (ToC) upon disc load. The ToC is stored in the lead-in area of the CD. When we skip from one track to the next, the ToC is used by the CD player to move the laser to the next time-coded marker.
The move to file-based playback brought trouble. When we rip a CD, the ToC is used to separate the CD’s single file into many files. A CD containing eight songs will give us eight files once ripped — one file for each song stored on our hard drive. One file for each song stored on a microSD card. One file for each song stored on a streaming service’s server.
And for some portable players, network streamers and audio playback software, this poses a challenge. To maintain the gapless integrity of the original CD (or LP), the next song must be pre-loaded before the currently playing song has finished. If a DAP, network streamer or audio playback software doesn’t do this – if it can only load the next song after the current song has finished playing – we will hear tiny gaps of silence between the songs on Pink Floyd’s Animals and longer gaps of silence between the songs on Wire’s Chairs Missing.
In reality, gapped playback might be less troubling to listeners of the Wire album than the Pink Floyd, but neither experience is as the artist intended. Further, for compilations and shuffled playback, gaps between tracks is probably a trivial issue. However, gapless playback is essential to the proper enjoyment of live albums and (especially) DJ mixes. Hearing gaps spliced between tracks renders Richie Hawtin’s CLOSE Combined unlistenable. Intra-song gaps, no matter how small, ruin the mix’s flow. No wonder the serious heads still rip CDs like this as a single track and have their software of choice read an associated .cue file to provide the track separators.
All of the above was ground covered by Primare’s Terry Medalen and me over lunch in Berlin during IFA 2018. I told him I’d not be keen to tackle one of his company’s streaming products until they’d bagged gapless playback. For their recently announced NP5 Prisma, Primare can do little about Chromecast’s lack of gapless playback – that’s a Google issue – but Roon has it long sorted, as does Spotify through their Connect program. Apple AirPlay and Bluetooth stream continuously from a smartphone or computer so no issues with gapless playback there. Where work had to be done by the Swedish engineers was on their Prisma platform that relies on UPnP to stream from a network share or directly-attached USB drive. Medalen is aware that Bubble UPnP and JRiver provide gapless workarounds but a product that relies on workarounds to get the job done is hardly a polished solution. And polished solutions are essential to those who aren’t tech-savvy.
Medalen and I sat down in Warsaw last weekend to continue our gapless conversation over coffee:
Further information: Primare