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Preservation architecture

Change the container.
Respect the footage.

Uncrush separates analysis, planning, writing, and verification so a narrow container change cannot quietly become a media change.

01

Safe path

Publication is the last step,
not the optimistic one.

The native faststart-v1 and verified MOV-to-MP4 remux paths implement this architecture. Browser processing remains planned, while broader compatibility and conversion remain in development.

  1. 01

    Analyze immutable source

    Read one stable source snapshot under explicit limits.

  2. 02

    Build a bounded plan

    Explain every approved range copy and container rewrite.

  3. 03

    Transform

    Stream supported bytes without unnecessary decoding or re-encoding.

  4. 04

    Reopen output

    Treat the generated candidate as a new, independent input.

  5. 05

    Analyze independently

    Apply the same parser and supported-profile checks again.

  6. 06

    Verify invariants

    Compare required encoded media and exact declared meaning.

  7. 07

    Publish after verification

    Release the candidate only when every required gate succeeds.

02

Boundaries

One mission.
Three evidence levels.

Current code · v0.1

Implemented

The native codebase analyzes supported MOV/MP4, creates verified same-container fast-start copies, and remuxes one closed QuickTime profile to verified MP4 while preserving H.264/AAC encoded media for the supported profile.

  • Bounded MOV/MP4 analysisReads the supported container profile with explicit limits and exact integer timing.
  • Canonical encoded-sample identityDescribes selected encoded video and audio samples in a stable, versioned form.
  • Direct safe-transform-v1 verificationCompares encoded payloads, timing, decoder setup, geometry, color, and audio meaning between supported files.
  • Native CLI foundationProvides analysis, identity, verification, verified same-container fast-start, and closed-profile MP4 remux commands.
  • Source-bound transformation planningBinds checked copy and rewrite actions to one exact immutable source snapshot.
  • Bounded streaming container writerCopies supported media through a reusable buffer without decoding or re-encoding it.
  • Verified faststart-v1Moves moov for same-container fast-start output and rewrites required absolute chunk offsets.
  • Generated-output re-analysisReopens the private candidate and analyzes it independently before publication.
  • Verified MOV-to-MP4 remuxConverts one closed QuickTime AVC/AAC wrapper profile to deterministic fast-start MP4 under safe-remux-v1.
  • Mandatory publication gatePublishes media only after the applicable safe-transform-v1 or safe-remux-v1 policy returns verified.

Current boundary

In development

Work on broader compatibility and conversion remains in development. It does not broaden the implemented closed profile today.

  • Broader compatibility and conversionFuture profiles require separate design, implementation, and preservation evidence before they can be called supported.

Later milestones

Planned

Browser/WASM processing, platform profiles, and controlled platform research require separate milestones and evidence.

  • Browser WASM processorIntended to run approved processing locally in a future browser experience.
  • Versioned platform profilesPlanned profiles will encode measured, reviewable preparation rules instead of folklore.
  • Controlled rendition experimentsLater research will compare retrieved delivery renditions under documented conditions.
  • Mobile applicationsiOS and Android experiences remain future work after the portable processing boundary exists.
03

What “preserve” means

Bytes and meaning
travel together.

Keeping encoded video and audio samples is necessary. It is not enough. Their order, decode and presentation timing, edit mapping, decoder configuration, geometry, color, and audio metadata also matter.

Unknown layout-coupled state fails closed. If Uncrush cannot prove that a transformation is safe under a named policy, the output must not be published as verified.