Constant Target Quality Encoding

Constant Target Quality (CTQ) is a rate control mode that targets a consistent, user-defined visual quality level, enabling the move away from a bitrate-first mindset. By adapting encoding decisions to scene complexity and perceptual importance, CTQ delivers more efficient compression while maintaining a consistent viewer experience.

The Challenge with Traditional HEVC Rate Control

Traditional rate control modes rely on fixed or constrained bitrate targets. While predictable from a bandwidth perspective, these approaches often struggle to maintain consistent visual quality across diverse content types.

Simple scenes may consume more bits than necessary, while complex scenes can suffer from visible artifacts when bitrate limits are reached. As a result, operators are forced to tradeoff between bitrate predictability and perceptual quality, often relying on manual tuning and content-specific presets.

CTQ was designed to remove this tradeoff by making visual quality the primary control signal.

What Is Constant Target Quality Encoding

Constant Target Quality, developed by MainConcept, is a perceptual rate control mode that prioritizes how video looks to the viewer rather than how many bits are allocated per second. Instead of specifying a target bitrate, users define a desired quality level. During encoding, CTQ dynamically allocates bits based on scene complexity and perceptual relevance, allowing bitrate to adapt naturally while maintaining a consistent visual result.

The outcome is predictable quality across a wide range of content, without the need for extensive manual optimization.

CTQ is available today for the MainConcept HEVC/H.265 SDK.

Ideal CTQ Use Cases

CTQ is well suited for workflows where consistent visual quality and efficient bitrate usage are critical.

CTQ in the MainConcept Video Quality Ecosystem

CTQ is part of a broader set of quality-focused technologies within the MainConcept portfolio.

While CTQ controls perceptual quality during encoding, tools such as VMAF-E and vScore enable objective quality measurement, evaluation, and optimization across encoding workflows. Together, these technologies help developers build efficient, quality-driven video pipelines.