Go backend:
- Add AudioCodec field to DownloadResult and DownloadResponse
- Extension download results can now include audio_codec/audioCodec
- ffmpegGetInfo and probeAudioQuality now return codec field
- Add trackItemBytes option to file.download() for custom progress handling
Flutter:
- Check audio_codec before container conversion
- Skip FLAC conversion if source codec is lossy (AAC, MP3, Opus, etc.)
- Prevents fake upscale from lossy to lossless containers
- Extract _formatDownloadProgressLabel() for cleaner code
- Show received/total size when bytesTotal is available
- Estimate total size from progress when only bytesReceived is known
- Add text overflow handling with ellipsis
New lyrics providers using Paxsenix API:
- Spotify: Synced lyrics from Spotify
- Deezer: Synced lyrics from Deezer
- YouTube: Lyrics from YouTube
- Kugou: Lyrics from Kugou (Chinese service)
- Genius: Plain text lyrics from Genius
Implementation:
- Add lyrics client implementations for all providers
- Smart search result scoring based on track name, artist, and duration
- Support for both synced (LRC) and unsynced lyrics formats
- Fallback search with simplified track names and primary artist
UI updates:
- Add provider entries to lyrics priority settings page
- Add display names for new providers in settings
FFmpeg doesn't always embed lyrics correctly to MP3 files. This adds
manual ID3v2.3 USLT (Unsynchronized Lyrics) frame writing after FFmpeg
metadata embedding to ensure lyrics are properly stored.
Implementation:
- Extract lyrics from metadata (UNSYNCEDLYRICS or LYRICS key)
- Build ID3v2.3 compliant USLT frame with UTF-16LE encoding
- Insert or replace USLT frame in existing ID3v2.3 tag
- Create new ID3v2.3 tag if file has no ID3 header
- Skip gracefully for unsupported ID3 versions or flags
Also includes minor audio analysis improvements:
- Consistent dynamic range calculation (peak - rms)
- Filter out 'unknown' and 'n/a' labels
- Add -vn -sn -dn flags for more robust stream selection
Audio Analysis Enhancements:
- Display codec name and container format
- Show decoded sample format (s16, s32, fltp, etc.)
- Add LUFS integrated loudness measurement (broadcast standard)
- Add true peak measurement (dBTP)
- Detect and count clipping samples per channel
- Estimate spectral cutoff frequency (helps detect fake upscales)
- Show per-channel statistics (Peak, RMS, DR, Clip count)
UI Improvements:
- MetricChip now handles long text with ellipsis
- Constrained max width for better layout
Cache version bumped to 4 to force rescan with new metrics.
- Replace inline format detection with convertibleAudioSourceFormat()
- Replace inline conversion rules with canConvertAudioFormat()
- Add unit tests for Dolby format detection and conversion rules
Audio Analysis:
- Add rescan capability by bumping cache version
- Display channel layout (stereo, 5.1, etc.) and bitrate
- Use astats filter for more accurate peak/RMS measurements
- Support more formats: mp4, ac3, eac3, mka, wv, ape, tta, aif
- Only report bit depth for codecs that store it (FLAC, ALAC, WAV)
- Validate cache for SAF content:// URIs
Conversion:
- Add AAC as conversion target format
- Recognize ALAC as lossless source
- Prevent accidental deletion when source and target URI match
- Store format and bitrate in database after conversion
Utilities:
- Add audio_conversion_utils.dart for centralized conversion logic
- Add isSameContentUri() helper for safe URI comparison
The HIGH-quality lossy format picker can now produce an AAC/M4A 320 kbps output alongside MP3 and Opus. FFmpegService.convertM4aToLossy/convertAudioFormat, the Dart queue pipeline, the Kotlin finalizer, and the library database format helper all route .m4a through a unified aac codec path and tag the resulting file with the M4A metadata writer. The Lossy Format setting gains a new option, and the track metadata convert dialog lists AAC next to the other targets.
Apple Music lyrics gain a 'eLRC word sync' switch (default off). When disabled the pax-to-LRC formatter strips inline word timestamps, producing line-synced LRC that is safer for players that choke on eLRC; enabling it restores the previous word-by-word behaviour. The change propagates through SetLyricsFetchOptions and invalidates the global lyrics cache on toggle.
Broad l10n migration: roughly 400 previously hardcoded English strings across queue, settings, track metadata, repo, audio analysis, setup and extension screens now live in the ARB catalog, with matching plural/placeholder forms. No behaviour change beyond localisation. Existing and new unit tests (lyrics eLRC toggle and Dart settings round-trip) pass.
Introduce AppRemoteConfigService which fetches a platform/version/locale-aware JSON payload from api.zarz.moe/v1/spotiflac-mobile/config and caches it in SharedPreferences. main_shell shows a one-shot announcement dialog (respecting dismissible, CTA, time window and version gates) when no update prompt is pending; dismissed IDs are persisted so each announcement surfaces only once.
Tweaks bundled in: the service health dot loses its blur halo in favour of solid Material 3 tones, and AppInfo gains the remote config endpoint constant. The share listener and SAF migration hook stay synchronous inside the post-frame callback so share-intent URLs never race the network-bound checks.
New unit tests cover the announcement CTA/active-window rules.
Zarz Eleutherius