How can an archive verify that an FFV1/Matroska transcode is lossless, and what do MediaConch policies and FADGI say?
To verify a lossless transcode, compare decoded-frame hashes: FFmpeg's framemd5 gives per-packet MD5, while its crc and framecrc muxers use Adler-32 (not CRC-32) on frames converted to raw; MediaConch's sample digitization policy checks Matroska v4+, a unique ID, FFV1 3.4+, GOP size 1 and slice CRCs, plus SD geometry.
To verify a lossless transcode, compare decoded-frame hashes: FFmpeg's framemd5 gives per-packet MD5, while its crc and framecrc muxers use Adler-32 (not CRC-32) on frames converted to raw; MediaConch's sample digitization policy checks Matroska v4+, a unique ID, FFV1 3.4+, GOP size 1 and slice CRCs, plus SD geometry.
Curator qualifications: Specifications and policy read 2026-10-22; no files encoded or hashed. framemd5 wording and FADGI 2014 comparison page from producer reading.
Limitations: Specifications and policy read 2026-10-22; no files encoded or hashed.
Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.
Structured fields
{
"citations": [
{
"url": "https://ffmpeg.org/ffmpeg-formats.html",
"note": "ffmpeg-formats.html (live) crc and framecrc muxers; MediaConch_SourceCode 93bd6874 Tools/Policies/sample_policy_4_mkv_ffv1_digitization.xml rule names"
},
{
"url": "https://github.com/MediaArea/MediaConch_SourceCode/blob/93bd68748f5f5d3c5fa32655ea43c83fad95c650/Tools/Policies/sample_policy_4_mkv_ffv1_digitization.xml",
"note": "ffmpeg-formats.html (live) crc and framecrc muxers; MediaConch_SourceCode 93bd6874 Tools/Policies/sample_policy_4_mkv_ffv1_digitization.xml rule names"
},
{
"url": "https://www.digitizationguidelines.gov/guidelines/video_reformatting_compare.html",
"note": "ffmpeg-formats.html (live) crc and framecrc muxers; MediaConch_SourceCode 93bd6874 Tools/Policies/sample_policy_4_mkv_ffv1_digitization.xml rule names"
}
]
}Evidence claims
- [sourced_fact] To verify a lossless transcode, compare decoded-frame hashes: FFmpeg's framemd5 gives per-packet MD5, while its crc and framecrc muxers use Adler-32 (not CRC-32) on frames converted to raw; MediaConch's sample digitization policy checks Matroska v4+, a unique ID, FFV1 3.4+, GOP size 1 and slice CRCs, plus SD geometry. · locator: ffmpeg-formats.html (live) crc and framecrc muxers; MediaConch_SourceCode 93bd6874 Tools/Policies/sample_policy_4_mkv_ffv1_digitization.xml rule names source
Rights
| component | license | hosting | redistribution | modification | training | Evidence and notes |
|---|---|---|---|---|---|---|
| documentation | unknown | permitted | permitted | unknown | unknown | Applies to this original summary only, not to the cited sources. |