UT Video
37c3317fd058; modified for Encode Wiki · CC BY-SA 4.0Ut Video is a fast lossless codec by Takeshi Umezawa, built as a better-compressing alternative to HuffYUV. It is light enough on the CPU to capture HD in real time, which makes it a common choice for lossless screen and video captures and editing intermediates. Files are noticeably larger than FFV1, but encoding and decoding are much faster.
The original Ut Video Codec Suite (GPL v2 or later, version 23.2.0) is a Windows VCM and DirectShow codec. FFmpeg ships an independent encoder and decoder, which is what most people use on Linux and macOS. Current Windows builds of the suite require a CPU with AVX2 and BMI2.
Encode with FFmpeg
Section titled “Encode with FFmpeg”ffmpeg -i input.mkv -c:v utvideo -pred median output.mkv-pred takes none, left (the default) or median. median gives smaller files at about the same speed. The FFmpeg encoder has no gradient prediction.
The encoder works in 8-bit yuv420p, yuv422p, yuv444p, gbrp and gbrap and converts anything else, so a 10-bit source is reduced to 8 bits. FFmpeg cannot encode the 10-bit Ut Video Pro family; use FFV1 for 10-bit lossless work.
For YCbCr, the FourCC records the matrix: FFmpeg writes ULH* (BT.709) when the stream is tagged BT.709 and ULY* (BT.601) otherwise. Add -colorspace bt709 for untagged HD sources, or the decoding application may convert with the wrong matrix.
Families and FourCCs
Section titled “Families and FourCCs”The suite contains several codec families. The FourCC in the file tells you which one:
| Family | FourCCs | Notes |
|---|---|---|
| Ut Video | ULRG, ULRA, ULY0/2/4, ULH0/2/4 | 8-bit RGB, RGBA and YCbCr. ULY* is BT.601 and ULH* BT.709. |
| Ut Video T2 | UMRG, UMRA, UMY2/4, UMH2/4 | Usually faster with lower compression; supports inter-frame compression. |
| Ut Video Pro | UQRG, UQRA, UQY0/2 | 10-bit. |
FFmpeg encodes only the first family. It decodes all three, but its T2 decoder has no inter-frame support, so use the Windows suite for T2 files encoded with inter-frame compression.
Pitfalls
Section titled “Pitfalls”- AVI is the traditional container because the Windows suite is a VfW/DirectShow codec. FFmpeg-based tools are just as happy with Matroska.
- Lossless only holds for the format Ut Video stores. Converting RGB to YUV, 10-bit to 8-bit or 4:4:4 to 4:2:0 loses data before compression.
- Files are large and there is no browser or hardware playback; make a viewing copy.