VapourSynth R79 lets vspipe hand uncompressed MKV with audio, video and timestamps to FFmpeg

VapourSynth R79 was published on August 7. vspipe now supports uncompressed MKV output, which the project says is mainly intended to pass audio, video and timestamps together into FFmpeg. That can simplify piping compared with handling the streams and timing metadata separately.

The release also improves caching for scripts with long cyclical request patterns, such as loops of 20 or more frames, allowing cache heuristics to adapt to larger cycles over time. A zimg API version-check bug is fixed. The release notes do not claim a new compressed format, quality improvement or speed gain for every script.

The useful change is synchronisation hygiene. Keeping audio, frames and timestamps inside one transient container can make an FFmpeg handoff easier to inspect and reproduce, but uncompressed media can have heavy bandwidth and storage demands. Benchmark the exact filter graph rather than assuming the cache change helps every job.

Validate frame count, time base, variable-frame-rate behaviour, channel layout and FFmpeg command compatibility on a short known clip before moving a production pipeline. Keep the previous environment reproducible until output hashes and sync checks pass.