Provir
Independent provenance for recorded music. We establish whether a file is what it was sold as.
The problem
A great deal of music sold as lossless is not. It was compressed once, decompressed and repackaged, and the buyer is charged for quality that is no longer in the file.
The industry knows. Distributors tell uploaders, in their own published guidelines, not to submit lossy files converted to FLAC. What nobody ships is a way to check. Every available tool looks for a missing top end, and above about 256 kbps there is very little left to find. The best of them still separates the two classes at that rate — but only at a false-positive rate far too high to accuse a named release, and none of them tells you which encoder was used.
The evidence
Provir reads what the encoder left behind in the audio itself. It needs no original to compare against and no metadata to trust.
| MP3 instrument | |
|---|---|
| full-band MP3, 320 kbps | 23 / 24 identified |
| MP3, V0 | 24 / 24 identified |
| genuine masters | 0 / 36 false positives |
| five other codecs | 0 / 180 false positives |
| Vorbis instrument | |
| Ogg Vorbis, quality 8 | 26 / 36 identified |
| genuine masters | 1 / 36 false positives |
| six other codecs | 0 / 216 false positives |
MP3 and Vorbis are read by two different mechanisms, so neither result depends on the other being right. Each instrument's false-positive count is over the codecs it does not claim, which is why the two denominators differ.
The Vorbis instrument produced one false positive, on a lossless file that had been band-limited. A later refinement of its fire rule removes that case at no cost in recall; the refinement was registered in advance and then confirmed on a second, independent 70-file set, but it was not in the instrument that produced the results above. We report the result the sealed instrument actually gave.
Never wrongly accusing a genuine master matters more to us than catching every fake. Our false-positive rate is measured per release rather than per file, which is the stricter of the two conventions.
Who it is for
Listeners and artists, who should be able to check what they bought or what they made without paying for the privilege. And anyone who sells recorded music and would rather find this in their own catalogue than have someone else find it for them.
Status
In active development and not yet publicly available. If you would like to be told when it is, or you audit a catalogue for a living, write to contact@provir.org.