# PFES-ENG-025 — Media Validation

**Status:** Active  
**Knowledge Cycle Stages:** Validate

## Purpose

Establish confidence that acquired media and representations accurately preserve the original engineering artifact.

## Engineering Problem

Images may be readable yet incomplete, malformed, incorrectly windowed, or missing authentication and descriptor information.

## Historical Engineering Evolution

Validation expanded from mount tests to hashes, filesystem checks, authentication behavior, emulator use, hardware comparison, and independent datasets such as Redump.

## Engineering Discoveries

- Validation confidence increases through independent agreement.
- No single method proves engineering completeness.

## Architectural Decisions

- Preserve unsuccessful validation.
- Record confidence and method.
- Use Redump when applicable, while retaining PF-specific evidence.

## Knowledge Produced

- Validation evidence
- Quality assessments
- Negative knowledge

## Knowledge Consumed

- Images
- Sidecars
- Hardware behavior
- Reference datasets

## Current Engineering State

Current methods include CRC/MD5/SHA hashes, Redump comparison, filesystem validation, emulator testing, hardware reads, authentication checks, and geometry consistency.

## Engineering Lessons

- Reference agreement is strong evidence but not the entire engineering package.

## Negative Knowledge

Project Frankenstein no longer assumes:

- Matching one hash proves every sidecar and resource is correct.
- Emulator success alone proves a dump.

## Current Implementations

- FriiDump output verification
- Redump comparison
- Hardware and emulator validation

## Future Implementations

- Automated media validation pipeline
- Confidence scoring

## Open Questions

To be expanded during engineering review.

## Why This Chapter Exists

Unvalidated media can poison every downstream conclusion.

## Validated HLDS GameCube Reference Case

Sonic Mega Collection (US) is currently the primary live-validation disc for HLDS GameCube acquisition.

Reference values:

- sectors: `712880`
- size: `1,459,978,240` bytes
- CRC32: `01b52739`
- MD5: `85a525df1481d0ad67d8761f832dca12`
- SHA-1: `06eb6d15b4d7f90ec0fed9ce9a77db41358d74ed`
- observed SHA-256: `30098da93f5de9ece8da44f8afdfb85cf9bcdc24d77131221e64e3038a529010`

Independent agreement across firmware revisions, hardware units, profile-derived vendor behavior, and Redump establishes a strong validation case. The same disc and hashes provide a practical regression target for future FriiDump and analyzer changes.

## Identity Validation Rule

Live SCSI INQUIRY identity and firmware revision are authoritative for profile matching when they disagree with a case label.

A validated GCC-4244 example has a `B101` case label while live INQUIRY reports revision `B103`. FriiDump correctly uses the live identity rather than inferring the active firmware from the sticker.

