soundcraft/docs/gaps.md

Where SoundCraft falls short of Pro Tools

Last reviewed: 2026-10-19 · Last updated: 2026-10-25 · Change: trivial (G-04: Clip Looping crossfade and loop count; previously trivial: G-08 and G-20: built-in plugin count, the sampler shipped) · Target: Avid Pro Tools Ultimate 2026.4.1

Every known shortfall, one entry each, ranked by how much it stops a Pro Tools user from doing real work in SoundCraft. This is the work list: pick from the top. Rows marked alpha blocker fail the core-workflow gate in roadmap.md and keep SoundCraft pre-alpha. Numbers and weights live in target-app-parity.md; the plan that orders these into milestones is roadmap.md. Hours are Opus 5.5 agent-hours (calibration in target-app-parity.md). Estimates marked "≈" are judgements; issue numbers are storytold/soundcraft GitHub issues.

When you close a gap, delete its entry (or shrink it) in the same PR, and bump the timestamp.

Ranked gaps

#	Gap	Dimension	Doc	Est. (h)
G-01	Alpha blocker. No channel routing or duplex low-latency path (device, rate and buffer choice done; ASIO opt-in)	Hardware	hardware-parity.md	15–25
G-02	Alpha blocker. No MIDI device input or output	Hardware / MIDI	hardware-parity.md	20–35
G-03	Alpha blocker. Cannot exchange sessions with Pro Tools (no AAF/OMF, no .ptx)	File formats	file-format-parity.md	50–90
G-04	Open correctness bugs in features counted as done (~25 issues)	Stability	this file	25–40
G-05	(Entitlement part: alpha blocker for the mix row) Third-party VST3s blocked in the signed macOS build; AU editors missing	Ecosystem	plugin-parity.md	15–25
G-06	(Record-to-disk part: alpha blocker for the tracking row) Sources decoded whole into RAM; recording into RAM	Performance	hardware-parity.md	15–25
G-07	Nothing is compared against Pro Tools' output (no fidelity harness)	Features	this file	20–30
G-08	Built-in plugin catalogue thin and unverified	Features	plugin-parity.md	80–120
G-09	English only, no string catalog, no CJK/RTL rendering	Localization	localization-parity.md	70–110
G-10	No control surfaces (HUI/MCU, EUCON)	Hardware	hardware-parity.md	40–70
G-11	No external sync (MTC, LTC, MIDI clock, video reference)	Hardware	hardware-parity.md	15–25
G-12	Immersive delivery: no Dolby Atmos/ADM BWF, MPEG-H, binaural	Features	file-format-parity.md	50–80
G-13	Sidechain inputs, ARA, out-of-process plugin sandboxing	Ecosystem	plugin-parity.md	30–50
G-14	Windows/Linux/Web exercised only lightly at runtime; no PR CI running the tests	Platforms / Stability	this file	20–40
G-15	Elastic Audio depth: one algorithm, no Elastic Pitch	Features	target-app-parity.md	30–45
G-16	Session templates, track presets, workspace browser, batch rename	Features	target-app-parity.md	25–40
G-17	Video: HEVC/DNx decode, video export, external timecode	Features / Formats	file-format-parity.md	30–50
G-18	Speech-to-text transcription	AI	this file	30–50
G-19	UI feel: generic plugin windows, shortcut collisions, pro-grade meters and scaling	UI/UX	ui-parity.md	60–100
G-20	MIDI/instrument depth: MIDI learn, notation editing	Features	target-app-parity.md	40–60
G-21	Compressed export (MP3, AAC/M4A, Ogg/Opus)	File formats	file-format-parity.md	10–20
G-22	Avid cloud services (collaboration, Sketch, Splice, sign-in)	Ecosystem	—	not estimated (owner decision)

Details

G-01. Audio interface support

• Done (2026-10-12): Setup › Playback Engine chooses the audio system, output and input device, sample rate and device buffer size (kept with the preferences, per machine; ui.audio_device for agents); f32 and 16/32-bit integer devices; ASIO behind the opt-in asio build feature (verified on Windows with an SSL 2+ at 128 samples).
• Missing: routing to physical channels (I/O Setup), one duplex stream on one clock (input and output are still separate cpal streams), latency reporting and record-offset compensation, ASIO in official builds (owner decision: Steinberg's SDK is proprietary or GPLv3), JACK, and verification on macOS and Linux. The mix still runs in fixed 512-sample blocks. setup.playback_engine still stores device/buffer_size in the session, unused.
• Evidence: code above; Playback Engine window says "Mix block size: 512 samples"; issue #42 (no input device selection, forced monitoring feedback with virtual routing).
• Impact: blocks tracking with any multichannel interface; latency makes overdubs hard.
• Estimate: ≈ 25–40 h (device enumeration and selection, buffer size, duplex stream with one clock, ASIO feature build, per-channel I/O mapping into I/O Setup, latency reporting and record-offset compensation). Needs hands-on hardware testing.

G-02. MIDI devices

• Missing: all MIDI hardware I/O. No midir/CoreMIDI/WinMM/ALSA sequencer code exists; setup.midi_input_devices and setup.midi_studio only store names. You cannot record from a keyboard, play a hosted instrument live, drive external synths, or send MIDI clock/MTC. midi_editor.rs:288 notes audition "needs a live MIDI input path".
• Impact: MIDI production is limited to drawing notes and importing SMF.
• Estimate: ≈ 20–35 h (device layer, realtime input to armed tracks and instruments with timestamps, MIDI record/merge/loop, thru, output tracks, clock out).

G-03. Session interchange with Pro Tools

• Missing: opening or saving .ptx/.ptf, AAF and OMF import and export (#40), Media Composer–compatible sessions. Our session format is .scraft JSON.
• Impact: the standard's main-format bar for beta. A Pro Tools user cannot bring a project in or hand one back; post-production (picture editors deliver AAF) is blocked.
• Estimate: AAF/OMF import + export ≈ 50–90 h (FilmCraft already writes AAF/OMF; we can learn from it but not share code). .ptx is proprietary and undocumented: owner decision on whether black-box format study is in the clean-room rules; not included in the estimate.

G-04. Correctness bugs in "done" features

Fixed (2026-10-19, #791): Float32 WAV and AIFF-C encoding retain finite samples above full scale. Whole-file and streaming tests cover both formats, integer clipping, and the existing NaN/infinity behavior. A bounce regression checks preserved headroom and file/report agreement with normalization off, then checks normalized output.

Fixed (2026-10-18): Mono device playback averages the stereo channels before output clipping, Fixed (2026-10-16): Master fader volume automation uses the first and last samples of each Fixed (2026-10-16): Aux, folder and master latency calculations now skip inserts already render block, matching track faders. A breakpoint at the next block no longer ramps the preceding block, and ramps reach their last-sample value. Regression tests cover nonzero render starts, one-sample callbacks and several block sizes. Interior automation breakpoints remain block-dependent.

disabled for producing NaN or infinity. Subsequent blocks compensate only for healthy inserts; regression tests verify rendered impulse timing, retained healthy latency and reset/retry at 64- and 512-sample blocks, with audio tracks as the control.

instead of discarding the right side. Surround mixes average both sides of the ITU stereo fold-down. Regression tests cover right-only and left-only audio, equal and opposite-polarity channels, clipping order, centered mono tracks, each 5.1 channel and 1-, 37- and 512-frame callbacks. Fixed (2026-10-16): Split into Mono now gives each output track its own source channel, including surround channels, instead of repeating channel zero. Clip edits, source timestamps, Undo/Redo and save/reopen are covered by regression tests; missing or empty media fails atomically.

Open (2026-10-25): the Clip Looping dialog (#1030) has no option to crossfade the loops into each other, and its Number of Loops field stops at 512, while Loop Length and Loop Until End of Session or Next Clip make up to 1000 loops.

Open on 2026-10-10 (several have PRs open): editing #3, #5, #140, #144; clip/session #86 (PR #123), #88 (PR #130), #91 (PR #124), #92 (PR #132); automation #104 (PR #134); mix/bounce #59 (PR #131), #103 (PR #133), #152; playback #101 (PR #129); MIDI #87, #98 (PR #125); import #89 (PR #128); CLI #95, #96 (PR #126, #127); MCP #145 (PR #146); web #63, #64, #136; Clip List #4 (PR #75); plugin view #6; shortcuts #7, #41; launch #142; Linux #45, #107.

• Impact: each one is small, but together they say "presence is not parity": an outside contributor found seven in one sitting (#116–#122).
• Estimate: ≈ 25–40 h at 0.5–1.5 h each, plus review of the open PRs.

G-05. Plugin hosting on macOS

• Missing: the com.apple.security.cs.disable-library-validation entitlement in the signed build, so hardened runtime refuses third-party VST3 bundles (#153, #149). AU editor views (crates/au-host/src/lib.rs header: "Not hosted yet: Audio Unit editor views"). Embedded CLAP GUIs; VST3 editors on Windows/Linux.
• Estimate: ≈ 15–25 h (entitlement ≈ 1 h; AU Cocoa views and VST3 HWND/X11 views most of it).

G-06. Memory-bound media

• Missing: streaming sources from disk; recording to disk. Every source is decoded whole into the SourcePool; takes accumulate in RAM until stop (PR #84 open).
• Impact: hour-long multitrack sessions and long takes exhaust memory; a crash during a long take loses it.
• Estimate: ≈ 15–25 h.

G-07. Fidelity harness against Pro Tools

• Missing: any measured comparison: null tests of bounces of the same material, fade curve and pan-law checks, plugin frequency/dynamics responses, elastic-audio quality, automation timing. Pro Tools is installed; it can be driven black-box with synthetic sessions (outputs kept under plan/, never committed).
• Estimate: ≈ 20–30 h for the harness and the first 20 scored cases; turns many "≈" in target-app-parity.md into measurements.

G-08. Built-in plugins

See plugin-parity.md: 27 processors + 3 instruments against Pro Tools' roughly 80 bundled processors and instruments; no fidelity checks; generic parameter UIs; EQ parametric request #139. ≈ 80–120 h.

G-09. Localization

See localization-parity.md: no catalog, every string literal in code; egui has no complex-script shaping or RTL; no CJK font fallback (PR #141 open). ≈ 70–110 h plus native-speaker review.

G-10. Control surfaces

None: no HUI or Mackie Control, no EUCON (Avid-proprietary, needs Avid's SDK: owner decision), no generic MIDI controller mapping. Pro Tools users on S1/S3/S4/S6/Dock or HUI devices can't switch. ≈ 40–70 h for HUI/MCU plus a mapping layer; hardware needed to verify.

G-11. Sync

No MTC/LTC chase or generation, no MIDI Beat Clock (setup.midi_beat_clock stores a flag only), no video reference or word clock awareness, no Satellite-style linking. ≈ 15–25 h after G-01/G-02.

G-12. Immersive delivery

No Dolby Atmos renderer integration, ADM BWF import/export, re-renders, binaural monitoring, MPEG-H (new in Pro Tools 2026.4), surround/object automation. ≈ 50–80 h; Dolby's renderer and SDKs are licensed, so we'd write our own ADM and object renderer.

G-13. Plugin ecosystem depth

No sidechain (key input) buses for any host; no ARA (Melodyne-style editing is a menu in Pro Tools); plugins run in-process, so a crashing plugin can take the session down. ≈ 30–50 h. AAX cannot be hosted (#109): Avid's AAX SDK licence and PACE signing; owner decision, likely never.

G-14. Platforms and CI

Only freebsd.yml and windows-arm64.yml run on pull requests, and only for manifest paths; nothing runs cargo xtask ci on PRs. Windows and Linux have startup and rendering reports (#41, #45, #107, #142). ≈ 20–40 h (a PR CI matrix plus runtime smoke tests on three OSes).

G-15. Elastic Audio depth

One warp algorithm; Pro Tools offers several per track (polyphonic, rhythmic, monophonic, varispeed, high-quality offline) plus Elastic Pitch and warp-marker editing depth. ≈ 30–45 h.

G-16. Session management

Session templates, track-preset recall UI and browser, workspace/sound browser with previews, batch rename (new in 2026.4), disk-usage and relink depth remain. Track-preset saves capture the current hosted-plugin state before writing (#661); recall UI, partial recall and preset browsing remain tracked in #639. ≈ 25–40 h.

G-17. Video and post

No HEVC, DNxHD/HR or AV1 decode; no bounce with video; no external timecode/9-pin; no iXML field-recorder conform. ≈ 30–50 h.

G-18. Speech-to-text

Pro Tools transcribes dialogue to a searchable transcript (upgraded in 2026.4). We have a settings command only. Needs an openly licensed local speech model. ≈ 30–50 h.

G-19. UI feel

See ui-parity.md. ≈ 60–100 h.

G-20. MIDI and instrument depth

MIDI learn, drum machine depth, notation editing (tuplets, lyrics, articulations, parts). ≈ 40–60 h.

G-21. Compressed export

Bounce writes WAV/BWF/RF64, AIFF and FLAC; Pro Tools also writes MP3 and AAC/M4A in Bounce Mix. ≈ 10–20 h (pure-Rust encoders).

G-22. Avid cloud services

Collaboration, cloud projects, Sketch, Splice, Learn, sign-in: 11 of the 30 menu leaves still missing. Out of scope unless the owner decides otherwise.

Revision history

Date	Change	Summary
2026-10-25	trivial	G-04: Clip Looping (#1030) lacks the loop crossfade option, and Number of Loops stops at 512 while length and fill make up to 1000 loops
2026-10-24	trivial	G-08: 27 processors + 3 instruments, as the plugin registry holds; G-20: the sampler shipped (#108), so it is no longer listed as missing
2026-10-19	trivial	G-04: Float32 encoding retains finite headroom (#791); integer clipping and non-finite handling retained
2026-10-18	trivial	G-04: mono device stereo/surround fold-down fixed and regression-tested; estimates unchanged
2026-10-16	trivial	G-04: master volume automation block boundaries fixed and regression-tested; estimates unchanged
2026-10-16	trivial	G-04: failed aux/folder/master inserts excluded from latency compensation after containment; estimates unchanged
2026-10-16	trivial	G-04: Split into Mono channel preservation fixed and regression-tested; estimates unchanged
2026-10-16	minor	G-16: capture current hosted-plugin state before saving a track preset (#661); broader preset work remains (#639)
2026-10-12	minor	G-01 shrunk: audio device, rate and buffer choice; opt-in ASIO
2026-10-10	minor	Marked the alpha blockers (G-01, G-02, G-03; parts of G-05 and G-06) from the core-workflow gate
2026-10-10	major	Created from the full re-measure against Pro Tools Ultimate 2026.4.1: 22 ranked gaps with evidence and estimates