libvpx-vp9 Good vs Best Deadline Settings

When encoding video using the libvpx-vp9 library in FFmpeg, the deadline parameter (configured via -deadline or -quality) controls the trade-off between encoding speed and compression efficiency. This article explains the practical differences between the good and best deadline settings, helping you choose the right configuration for your video rendering pipeline.

Understanding the Deadline Parameter

The libvpx-vp9 encoder offers three target quality/speed deadlines: realtime, good, and best. While realtime is designed for live streaming where encoding must happen instantly, good and best are intended for two-pass or single-pass offline encoding where quality is prioritized over real-time processing.

The “good” Deadline Setting

The good setting is the default option for libvpx-vp9 and is widely considered the industry standard for most encoding tasks.

• Performance: It offers a balanced approach, delivering high visual quality at a reasonable encoding speed.
• Flexibility: When using good, you can fine-tune the speed and quality ratio using the -cpu-used parameter (ranging from 0 to 5). A lower -cpu-used value (like 0 or 1) results in higher quality but slower encoding, while a higher value (like 4 or 5) speeds up the process with a minor hit to quality.
• Best For: Almost all general-use cases, including web streaming, video-on-demand (VOD) platforms, and personal media libraries.

The “best” Deadline Setting

The best setting instructs the encoder to prioritize compression efficiency above all else, exhaustively analyzing the video to save every possible bit.

• Performance: It is notoriously slow. Encoding with the best setting can take multiple times longer than the good setting, often resulting in agonizingly long render times.
• Quality Gains: While it technically delivers the highest possible quality-per-bitrate, the visual improvement over good (especially good at low -cpu-used settings) is usually imperceptible to the human eye. The mathematical improvement (measured in PSNR or VMAF) is highly marginal.
• Best For: Archival encoding where CPU time and electricity costs are irrelevant, or very short, high-profile clips where maximizing bandwidth efficiency is the absolute highest priority.

Direct Comparison

Recommendation

For 99% of video projects, you should use -deadline good (or -quality good in newer FFmpeg versions). If you want to maximize quality under the good deadline, pair it with -cpu-used 0 or -cpu-used 1. This configuration will yield a video file that is virtually identical in visual quality to one encoded with the best deadline, but it will finish encoding in a fraction of the time.