A lossless codec preserves the picture samples it receives. A dependable video archive also needs the right audio, timing, metadata and file handling. Choose a workflow around those requirements, then create convenient viewing copies from the retained source.
Separate the codec, container and workflow
| Term | Meaning | Practical implication |
|---|---|---|
| Codec | The method used to encode and decode a media stream. | Identify the video and audio codecs separately. |
| Container or wrapper | The file structure that holds streams and associated information. | An .mkv, .mov or .mp4 suffix alone cannot establish picture quality. |
| Lossless encoding | Decoded samples reproduce the samples supplied to that encoder. | Check conversions and filters before encoding, as well as the codec setting. |
| Visually lossless | A perceptual judgment or production target. | Evaluate it for the task; it does not establish exact sample equality. |
A file can contain lossless video and lossy audio, or retain the image while losing a subtitle track. Start by listing what matters: picture samples, dimensions, frame timing, aspect ratio, scan order, color interpretation, audio channels, subtitles, timecode and descriptive notes.
Lossless encoding preserves what it receives. Scaling, deinterlacing, color-space conversion or reducing bit depth before that step can change the samples. A lossless output codec cannot reverse those earlier decisions.
Choose a role for each file
Retain the original acquisition or checked transfer whenever practical. Native DV, HDV or camera files hold evidence about how the recording arrived. A new lossless file can serve another preservation or processing purpose, but converting a lossy source cannot reconstruct information discarded during its original encoding.
| Role | What to keep | Decision to document |
|---|---|---|
| Original or native transfer | The source file set plus capture or copying notes. | Was it copied, captured as a digital stream, or captured from a playback signal? |
| Preservation derivative | A tested, documented representation suited to long-term retention. | Which streams, sample properties and metadata were preserved or changed? |
| Editing copy | A format that the editing system handles reliably. | Is it lossless, lossy, or a proxy, and how does it relate to the source? |
| Viewing copy | A convenient file for the intended player or sharing destination. | Which resolution, audio tracks, subtitles and processing were used? |
The IASA video-preservation guidelines, section B (PDF) distinguish acquisition and preservation decisions and explain why source type matters. A family collection and a staffed archive may choose different operational workflows; both benefit from retained sources and a documented conversion path.
Where FFV1 fits
The Library of Congress describes FFV1 as a lossless intra-frame codec developed within FFmpeg and identifies FFV1 in Matroska as a preferred format in its file-based video recommendations. It is one well-documented option for preservation work, with tools for encoding and checking.
Choose it when your workflow can produce, inspect, store and maintain the files. Verify whether your editor or intended player supports the complete file. A separate viewing copy may be easier for everyday use. Test representative material before making a collection-wide conversion.
Keep video coding separate from container and metadata decisions. Confirm audio, captions, timecode and any external descriptive files explicitly. Saving into a familiar wrapper does not guarantee that every source field survives.
Copy, rewrap or transcode deliberately
An ordinary file copy retains the file bytes. Rewrapping moves encoded streams into another supported container. Transcoding decodes and re-encodes media, potentially with filtering. The FFmpeg stream-copy documentation describes stream copying without decoding or encoding, and notes that container restrictions can make a proposed combination unsuitable.
A successful rewrap can preserve encoded picture data while changing the file’s structure or metadata. A successful transcode can retain the picture samples yet omit an audio track. Inspect stream selection and compare the result with an explicit checklist.
Use MediaInfo or a comparable inspection tool to record the actual codecs, frame size, rate, scan information, duration and audio layout. Save the report before and after conversion. A report helps explain the file; playback and completeness checks remain necessary.
Verify the result at three levels
- File integrity: create a checksum baseline for each retained file. Compare copies against it and investigate later changes. A matching checksum establishes byte identity to that baseline.
- Technical properties: compare required streams, duration, frame dimensions, rate, aspect, scan order, color information and audio channels. Test complete decoding for errors with suitable software.
- Content: review the beginning, ending, scene boundaries, motion, speech sync and captions. For important material, review the whole program and confirm every expected segment.
To demonstrate sample equality after a lossless transcode, compare decoded frames using a controlled method that keeps the same pixel representation and accounts for timing. Whole-file checksums will differ between differently encoded or wrapped files. Treat a checksum match, a clean decode and a content review as answers to different questions.
Retain conversion settings, software versions and warnings. Use the video transfer log to connect the source with its derivatives and verified backups.
Budget storage with measured samples
Lossless compression depends on picture content and input characteristics. Encode a representative sample, measure its size and duration, then allow extra capacity for variation, working files and backups. Flat screen graphics and noisy camera footage can behave quite differently.
Store independent copies in separate locations and periodically verify their integrity and readability. Keep the original media and documentation where practical. For source-specific steps, see MiniDV tapes, HDV recordings and DVD camcorder discs.