Flint

A PC companion for the Sony NW-A50-series Walkman and Cinder: copy a music library onto the player, keep likes and scrobbles in step, and give every track Sony's SensMe mood and tempo data — without touching the files on your PC.

Status: early rewrite. Flint replaces the Python Sony-sync tool, which remains the working version until Flint reaches it. Nothing here is released yet.

SensMe, without the bloat

SensMe channels on the Walkman need an analysis tag in each file. Sony's Music Center writes one into your PC library, and those files have been reported to grow by almost a megabyte each. Flint does it differently:

• It runs Sony's own analysis engine (MMLib11.dll, installed with Music Center for PC) over each track once, and keeps the result in its own cache — about 6 KB per track.
• It writes that 6 KB only into the copy it puts on the Walkman — a FLAC SMFM block or an MP3 GEOB frame, the same containers Sony uses. Your PC files are never modified.
• The Walkman's own scanner turns the tag into channels, the same as for Music Center's tags — so this works on stock firmware as well as Cinder.

Flint does not include Sony's engine. SensMe analysis needs Music Center for PC installed on the same Windows machine; everything else in Flint works without it.

Copying a library to the player

flint scan "D:\\Music"                              analyse once, into Flint's cache
flint sync "D:\\Music" --to E:\\ --to F:\\ --playlists "D:\\Playlists"     a dry run
flint sync "D:\\Music" --to E:\\ --to F:\\ --playlists "D:\\Playlists" --apply

Albums are the unit that moves, and an album is never split across the internal memory and the card. Albums that share a playlist stay together, so no playlist spans two volumes, and an album already on a volume stays there. Each volume gets whatever space is free on it, less half a gigabyte of headroom; --gb N sets a budget instead. --no-sensme copies without tagging.

Each copy is written to a temporary file and renamed, so an interrupted transfer leaves either the old file or the new one. Every volume carries flint-manifest.tsv, recording what each copy was made from — without it, a SensMe-tagged copy is larger than its source and would be copied again on every run, for ever.

Checking for fake FLACs

flint check looks for FLACs that are not the lossless audio they claim to be. It needs FFmpeg, and nothing else — no Music Center, no Walkman.

flint check "D:\Music"            every FLAC under a folder
flint check track.flac --verbose  one file, with its spectrum

Verdict	What was found
LOSSY	The sound stops dead at an encoder's lowpass frequency, or stops at one and the top band is switched off in a third of loud frames
SUSPECT	It stops between 19.5 and 21 kHz: a high-bitrate encoder, or simply the master
UPSAMPLED	An 88.2 kHz or higher file with nothing real above CD or DAT bandwidth
PADDED	A 24-bit file whose samples only use 16 bits
DAMAGED	FFmpeg reported errors decoding the stream

Measured against transcodes of four albums (each encoded and turned back into FLAC):

Source	Caught
MP3 128 kbit/s	4 of 4
MP3 320 kbit/s	4 of 4 (2 as LOSSY, 2 as SUSPECT)
Opus 160 kbit/s	4 of 4 (2 as LOSSY, 2 as SUSPECT)
Vorbis q6	1 of 4
LAME V0, FFmpeg AAC 256 kbit/s	0 of 4 — these keep sound almost to 22 kHz, so there is nothing to see
Upsampled to 96 kHz, and 16-bit padded to 24	4 of 4 each
The four untouched originals	none flagged

A clean result is not proof. It means none of the usual signs. Equally, SUSPECT is not an accusation: plenty of genuine masters stop at 20 kHz. Results are cached by audio content, so a retagged or moved file is not decoded twice.

Layout

Crate	What it is
flint-core	FLAC metadata and ID3v2 reading and writing, the SMFMF chunk format, and the decode → engine pipeline
flint	The command-line tool
sensme-helper	A 32-bit Windows helper that loads MMLib11.dll (the engine is 32-bit, Flint is not)

Building

cargo test
cargo build --release --target x86_64-pc-windows-gnu -p flint
cargo build --release --target i686-pc-windows-gnu -p sensme-helper

Both Windows targets cross-compile from Linux with mingw-w64.

Licence

MIT. Sony's engine is not part of this repository and is not redistributed.