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Technical Encoding Guides

Deep-dive technical documentation on video bitrates, compression mathematics, modern video codecs, and OBS Studio live encoder configuration.

Last Updated: November 4, 2026

Quick Navigation: 1. Bitrate & BPP Mathematics 2. H.264 vs H.265 vs AV1 vs VP9 3. Rate Control (CBR vs VBR vs CRF) 4. OBS Studio Optimal Settings 5. FFmpeg Production Cookbook
Chapter 1

Understanding Video Bitrate & Bits Per Pixel (BPP)

Bitrate is the volume of digital data processed or transmitted per unit of time, typically measured in kilobits per second (kbps) or megabits per second (Mbps). Remember that 1 Byte consists of 8 bits (1 Byte = 8 bits).

The Universal BPP Quality Formula

Bits Per Pixel (BPP) = (Video Bitrate in bps) / (Width × Height × Frame Rate)

BPP provides a resolution-agnostic benchmark to determine if a video stream has adequate bandwidth to avoid macroblocking:

  • • BPP < 0.05: Low fidelity. Rapid camera pans will exhibit blur and blocky pixelation.
  • • BPP 0.07 – 0.10: Good quality sweet spot for H.264 live streaming (e.g. 1080p60 at 6,000 kbps = 0.048 BPP, which is why 900p60 at 6,000 kbps achieves a superior 0.069 BPP).
  • • BPP 0.12+: High fidelity archive quality, visually lossless for general streaming.

Why Higher Resolutions Need Lower BPP

Counter-intuitively, 4K video does not need the same BPP score as 720p. As resolution increases, spatial redundancy increases dramatically — adjacent pixels in a 4K frame share nearly identical color values. Transform block sizes scale from 16×16 up to 64×64 or 128×128, allowing 4K video to look visually immaculate at a BPP of only 0.055 to 0.065.

Chapter 2

Modern Codec Architecture: H.264 vs H.265 vs AV1 vs VP9

Video codecs compress images by partitioning frames into blocks and predicting motion over time. Here is how modern codecs compare architecturally:

H.264 / AVC (Advanced Video Coding)

Introduced in 2003, H.264 divides images into fixed 16×16 Macroblocks and supports up to 9 directional intra-prediction modes. It is natively decoded by 100% of consumer electronics on Earth. However, high-frequency textures require twice the bitrate of modern alternatives.

Efficiency Baseline: 1.0× (Reference Standard)

H.265 / HEVC (High Efficiency Video Coding)

Replaces fixed macroblocks with variable Coding Tree Units (CTUs) up to 64×64 and expands directional prediction to 35 modes. Saves ~40% to 50% data over H.264, but is hindered by fragmented patent pool royalties (MPEG-LA, HEVC Advance, Velos Media).

Efficiency: ~0.60× of H.264 (~40% bandwidth saved)

AV1 (AOMedia Video 1)

The modern royalty-free open standard backed by Google, Apple, Netflix, and Intel. Introduces 128×128 Superblocks, 56 directional prediction modes, and advanced intra-block filtering. Saves 50% bandwidth over H.264 with hardware encoders on modern GPUs.

Efficiency: ~0.50× of H.264 (~50% bandwidth saved)

VP9 (Google Open Codec)

Google's open-source codec powering YouTube's 1440p and 4K playback. Features up to 64×64 blocks and 10-bit support. Decoded smoothly on all mobile devices and desktop web browsers with zero licensing fees.

Efficiency: ~0.70× of H.264 (~30% bandwidth saved)
Chapter 3

Rate Control Explained: CBR vs. VBR vs. CRF / CQP

Rate control determines how bits are distributed across seconds of video:

CBR (Constant Bitrate)

Maintains a flat data rate regardless of scene complexity. Padds quiet scenes with empty data and constrains rapid motion.

When to use: Mandatory for live RTMP streaming (Twitch, YouTube Live, Kick) where network ingestion cannot tolerate bitrate spikes.

VBR (Variable Bitrate)

Allocates data dynamically based on motion. Static scenes use minimal data, preserving bandwidth for explosive action.

When to use: Ideal for VOD uploads (YouTube, Vimeo, TikTok, Instagram). Always use 2-Pass VBR for targeted file sizes.

CRF (Constant Rate Factor)

Perceptual quality rate control. Does not aim for a specific bitrate; instead guarantees consistent visual quality throughout.

When to use: Local archive recording and Handbrake/FFmpeg encoding. Recommended value: CRF 18 (visually lossless) to CRF 23.

Chapter 4

OBS Studio Master Encoder Configuration Guide

Recommended parameters for OBS Studio (Output Mode: Advanced > Streaming tab):

Encoder Setting NVIDIA NVENC (RTX GPUs) x264 (CPU Encoding) Technical Explanation
Rate Control CBR CBR Constant Bitrate is mandatory for live RTMP streaming to prevent ingestion disconnects.
Keyframe Interval 2 seconds 2 seconds Required by Twitch, YouTube, Kick, and Facebook. Never leave on 0 (Auto).
Preset P5: Slow (Good Quality) or P6 Medium or Fast Balances motion vector search depth with encoder latency.
Tuning High Quality None / Film Prioritizes visual detail over ultra-low latency sub-frame modes.
Multipass Mode Two Passes (Quarter Resolution) N/A Enables dual-pass rate distribution on NVIDIA NVENC without CPU overhead.
Max B-frames 2 2 Bidirectional predictive frames improve compression in gradual fades.
Chapter 5

Production FFmpeg Recipes Cookbook (Ready to Copy)

Handcrafted terminal recipes for video engineers, editors, and automation scripts:

1. Two-Pass Exact File Size Target (e.g. 50 MB for Discord/Email)

Calculates bit budget to ensure final MP4 never exceeds your size limit:

ffmpeg -y -i input.mp4 -c:v libx264 -b:v 2500k -pass 1 -an -f null /dev/null && \
ffmpeg -i input.mp4 -c:v libx264 -b:v 2500k -pass 2 -c:a aac -b:a 128k output_target_size.mp4
2. Convert Master Footage to High-Fidelity AV1 (SVT-AV1)

Cuts file size in half with visual losslessness using modern AV1:

ffmpeg -i input.mov -c:v libsvtav1 -preset 5 -crf 24 -c:a aac -b:a 192k output_av1.mp4
3. Upscale 1080p to 1440p (Lanczos 3-Point Scaling for YouTube)

Forces YouTube's ingestion robots to allocate the VP9/AV1 codec:

ffmpeg -i input_1080p.mp4 -vf "scale=2560:1440:flags=lanczos" -c:v libx264 -b:v 24000k -maxrate 28000k -bufsize 48000k -c:a copy output_1440p_upscaled.mp4
4. Crop 16:9 Landscape Video to 9:16 Vertical (TikTok / Reels)

Crops the center vertical slice and scales to 1080x1920:

ffmpeg -i input_16x9.mp4 -vf "crop=ih*(9/16):ih,scale=1080:1920" -c:v libx264 -b:v 8000k -c:a aac -b:a 128k output_vertical_9x16.mp4