AV1 Codec - Quantization

AQ Mode

AQ Mode (Adaptive Quantization Mode) Controls how much the quantization (and thus the compression) is dynamically adapted to the image content in order to achieve better visual quality – especially for complex or highly varying image areas

• 0 – Off (Default)

  Adaptive quantization is disabled. All image areas are treated equally, which can result in simpler but less efficient compression.

• 1 – Variance AQ

  Adjusts quantization based on the variance within a block. Areas with high detail (high variance) receive lower quantization (better quality), while smooth areas receive higher quantization.

• 2 – Complexity AQ

  Uses a more complex metric that goes beyond variance to determine which parts of the image need more bits

• 3 – Cyclic Refresh AQ

  Uses a cyclic renewal of regions in the image, where certain areas are encoded with better quality

Delta Qindex Mode

"Delta Qindex Mode" determines how the quantization indices (Q-index) are adjusted between different image areas (macroblocks). The goal is to improve visual quality for specific content or usage goals.

• 0 – Off: No adjustment of the Q indices – a constant quantization value is used
• 1 – Deltaq Objective (Default): Standard mode. Uses objective metrics (e.g., variance, complexity) to locally adjust the Q-index and improve visual quality.
• 2 – Deltaq Placeholder
• 3 – Key Frame Visual Quality: Specifically improves the quality of keyframes, which is particularly important for editing points or scene changes
• 4 – User Rating Based Visual Quality Optimization
• 5 – HDR Video: Optimizes quantization specifically for HDR (High Dynamic Range) content to better preserve the expanded brightness and color space
• 6 – Variance Boost All Intra: For all-intra coding (each frame intra-coded). Enhances quality in highly varied image areas, ideal for editing or high-quality single-frame analysis.

Deltaq strength

Deltaq strength Controls the strength of the local adjustment of the quantization index (Q-index) within an image, i.e. how much the quantization varies in different areas

Disable Trellis Quant

Disable Trellis Quant disables trellis quantization, an advanced optimization technique used during the quantization phase of video compression

• 0 - false: means that trellis quantization is enabled
• 1 - true: means that trellis quantization is disabled
• 2 - true for rd search: indicates that trellis quantization is specifically disabled during the rate distortion (RD) search
• 3 - true for estimate yrd search (default): means that trellis quantization is disabled during the "estimate yrd search" phase
  This is the default setting

Use Adaptive quantize_b

Use Adaptive quantize_b Improve visual quality at a given bitrate