Digital-Subband-Video-2

As of August 29, 2026 the DSV2 bitstream is frozen (v2.8)

DSV2 is a lossy/lossless video codec using wavelets and block-based motion compensation. It performs best at medium-low to medium-high bitrates at resolutions between ~352x288 (CIF) to 1920x1080 (FHD). Comparable to MPEG-4 Part 2 and Part 10 (H.264) (P frames only) in terms of efficiency and quality.

Example comparison (More can be found at the bottom of the README):

Stefan CIF minih264:

https://github.com/user-attachments/assets/e5695fa1-afa7-4205-9901-1993569efd88

DSV2:

https://github.com/user-attachments/assets/37283f25-4ca7-4587-aee6-5b619301b8d0

Note PDFs are out of date. They reflect the codec as it was when it was first uploaded here.

DSV2 Features (refer to PDF in repo for more detail)

compression using multiresolution subband analysis instead of DCT
- also known as a wavelet transform
up to quarter-pixel motion compensation
4:1:0, 4:1:1, 4:2:0, 4:2:2 (+ UYVY) and 4:4:4 chroma subsampling formats
adaptive quantization
in-loop filtering
lossless coding support
intra and inter frames with variable length closed GOP
- no bidirectional prediction (also known as B-frames). Only forward prediction with previous picture as reference

Improvements and New Features since DSV1

in-loop filtering after motion compensation
more adaptive quantization potential
skip blocks for temporal stability
new subband filters + support for adaptive subband filtering
better motion compensation through Expanded Prediction Range Mode (EPRM)
quarter pixel compensation
lossless coding support
psychovisual optimizations in the codec and encoder design

--- for more detailed information please refer to the informal specification document (DSV2_spec.pdf) in the repository.

Encoder Features (specific to this implementation of the DSV2 spec)

single pass average bitrate (ABR) or constant rate factor (CRF) rate control
more advanced Human Visual System (HVS) based intra block mode determination
new HVS based intra frame adaptive quantization
more complex scene change detection
hierarchical motion estimation
better temporal adaptive quantization
written to be compatible with C89

Approximate quality guide for encoding:
qp 0-20 = very low quality
qp 20-30 = low quality
qp 30-40 = medium-low quality
qp 40-50 = medium quality
qp 50-70 = medium-high quality
qp 70-90 = high quality, around qp 70 is the beginning of 'visually lossless'
qp 90-99 = very high quality (visually lossless)
qp 100 = mathematically lossless

--- for more detailed information please refer to the encoder information document (DSV2_encoder.pdf) in the repository.

Limitations

no built-in interlacing support
only 8 bits of depth per component supported
frame sizes must be divisible by two

This code follows my self-imposed restrictions:

Everything must be done in software, no explicit usage of hardware acceleration.
No floating point types or literals, everything must be integer only.
No 3rd party libraries, only C standard library and OS libraries for window, input, etc.
No languages used besides C.
No compiler specific features and no SIMD.
Single threaded.

Compiling

C Compiler

All you need is a C compiler.

In the root directory of the project (with all the .h and .c files):

cc -O3 -o dsv2 *.c

Zig build system

If you have Zig installed, you can use the build.zig file to compile the project. Building requires Zig version ≥0.13.0.

Ensure you have Zig & git installed
Clone this repo & enter the cloned directory:

git clone https://github.com/LMP88959/Digital-Subband-Video-2
cd Digital-Subband-Video-2

Build the binary with Zig:

zig build

Note: If you'd like to specify a different build target from your host OS/architecture, simply supply the target flag. Example: zig build -Dtarget=x86_64-linux-gnu

Find the build binary in zig-out/bin. You can install it like so:

sudo cp zig-out/bin/dsv2 /usr/local/bin

Now, you should be all set to use the compiled dsv2 binary.

Running Encoder

Sample usage:

./dsv2 e -inp=video.y4m -out=compressed.dsv -y4m=1 -qp=60 -gop=48

Running Decoder

Sample usage:

./dsv2 d -inp=video.dsv -out=decompressed.y4m -y4m=1 -out420p=1

NOTE: if -inp= and -out= are not specified, it will default to standard in / out (stdin/stdout). Only .yuv (one file containing all the frames) and .y4m files are supported as inputs to the encoder.

Notes

This codec is by no means fully optimized, so there is a lot of room for performance gains. It performs quite well for what it is though.

Wavelet Codec Testbench

Check out this open source / work in progress wavelet codec testbench by Gianni Rosato!
https://github.com/gianni-rosato/wavelet-bench

If you have any questions feel free to leave a comment on YouTube OR join the King's Crook Discord server :)

YouTube: https://www.youtube.com/@EMMIR_KC/videos

Discord: https://discord.gg/hdYctSmyQJ

itch.io: https://kingscrook.itch.io/kings-crook

The BC2 Color Space

A pseudo-perceptual color space designed to be faster than existing perceptual color spaces while also demonstrating more appealing subsampling and quantization artifacts compared to typical YCbCr.
It can easily be used as a drop-in replacement for 8-bit YUV, the image/video viewer just needs to know how to decode BC2, see the bc2 directory in the repository to learn more!

Original vs YCbCr 4:2:0 @ 132kb vs BC2 4:2:0 @ 130kb (click to expand/download):

Example videos:

The H.264 file sizes were within a few kilobytes of their respective DSV2 file size.
H.264 examples were encoded using https://github.com/lieff/minih264 using -speed0 (best quality) unless otherwise stated
DSV2 examples were encoded with -effort=10 (best quality)

Husky CIF - 29.97fps, GOP = 60 minih264:

https://github.com/user-attachments/assets/4ae22745-0d74-4a37-96b8-dc427dce720b

DSV2:

https://github.com/user-attachments/assets/fb0b414c-4ff1-4ab6-a823-e205f358f09e

Mobile CIF - 29.97fps, GOP = 60 minih264:

https://github.com/user-attachments/assets/5562d96d-092c-46da-b0ab-1063bd0587a6

DSV2:

https://github.com/user-attachments/assets/0f66f580-60f9-4d54-b19a-c8dc9a9cbf1d

Parkrun 1280x720 - 50fps, GOP = 250

minih264:

https://github.com/user-attachments/assets/bcc408bd-6d5b-4725-b26e-307eee21ba56

x264 (encoded via ffmpeg with -c:v libx264 -preset superfast -crf 29.8 -refs 1 -coder vlc -bf 0 -g 250):