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FFmpeg H.265/HEVC Encoding Guide

Overview

This document covers video conversion methods from H.264 to H.265 (HEVC) using FFmpeg and optimal settings.

Basic Commands

Simplest Conversion

ffmpeg -i input.mp4 -c:v libx265 -crf 28 -c:a copy output.mp4

ffmpeg -i input.mp4 \
  -c:v libx265 \
  -crf 23 \
  -preset slow \
  -profile:v main \
  -pix_fmt yuv420p \
  -c:a aac -b:a 192k \
  -map_metadata 0 \
  -movflags use_metadata_tags \
  output.mp4

CRF (Constant Rate Factor) Settings

CRF Range

CRF Value Quality Use Case
0 Lossless Archiving (very large file size)
18-20 Visually lossless High quality archiving
23 Default General use
28 Good File size savings
35+ Low quality Not recommended

H.264 ↔ H.265 CRF Conversion Formula

H.265 CRF ≈ H.264 CRF + 4~6

Example: H.264 CRF 23 ≈ H.265 CRF 27-29

# To maintain H.264 quality, lower CRF by 4-6 for H.265
# Example: H.265 quality equivalent to H.264 CRF 23
ffmpeg -i input_h264.mp4 -c:v libx265 -crf 19 output.mp4

Preset Options

Speed vs Quality Trade-off

Preset Speed File Size Recommended Use
ultrafast Fastest Largest Testing
superfast Very fast Very large Quick conversion needed
veryfast Fast Large Real-time encoding
faster Fast Large Fast batch work
fast Medium Medium General use
medium Medium Medium Default
slow Slow Small Recommended
slower Very slow Very small Final output
veryslow Slowest Smallest Maximum compression needed 
# Recommended: slow preset for good quality/size ratio
ffmpeg -i input.mp4 -c:v libx265 -crf 23 -preset slow output.mp4

Metadata Preservation

Basic Metadata Copy

ffmpeg -i input.mp4 \
  -c:v libx265 -crf 23 \
  -c:a copy \
  -map_metadata 0 \
  output.mp4

Full Metadata Preservation (Including GPS)

ffmpeg -i input.mp4 \
  -c:v libx265 -crf 23 \
  -c:a copy \
  -map 0 \
  -map_metadata 0 \
  -movflags use_metadata_tags \
  output.mp4

Complete Metadata Restoration Using ExifTool

# 1. First convert with FFmpeg
ffmpeg -i original.mp4 -c:v libx265 -crf 23 converted.mp4

# 2. Copy metadata with ExifTool
exiftool -tagsFromFile original.mp4 converted.mp4

# 3. Restore file timestamps
touch -r original.mp4 converted.mp4

Audio Processing

ffmpeg -i input.mp4 -c:v libx265 -crf 23 -c:a copy output.mp4

Audio Re-encoding (When Needed)

# AAC encoding
ffmpeg -i input.mp4 \
  -c:v libx265 -crf 23 \
  -c:a aac -b:a 192k \
  output.mp4

# Maintain original audio quality (requires libfdk_aac)
ffmpeg -i input.mp4 \
  -c:v libx265 -crf 23 \
  -c:a libfdk_aac -vbr 5 \
  output.mp4

Advanced Settings

VMAF 95 Achievement Settings (2025 Benchmark)

ffmpeg -i input.mp4 \
  -c:v libx265 \
  -preset slow \
  -crf 20.6 \
  -g 600 \
  -keyint_min 600 \
  -tune fastdecode \
  -c:a copy \
  -map_metadata 0 \
  output.mp4

10-bit Encoding (HDR Compatible)

ffmpeg -i input.mp4 \
  -c:v libx265 \
  -crf 22 \
  -preset slow \
  -profile:v main10 \
  -pix_fmt yuv420p10le \
  output.mp4

2-Pass Encoding (Fixed Bitrate)

# Pass 1
ffmpeg -i input.mp4 \
  -c:v libx265 \
  -b:v 5M \
  -preset slow \
  -pass 1 \
  -an \
  -f null /dev/null

# Pass 2
ffmpeg -i input.mp4 \
  -c:v libx265 \
  -b:v 5M \
  -preset slow \
  -pass 2 \
  -c:a copy \
  output.mp4

Batch Conversion Scripts

Convert All MP4s in a Single Folder

#!/bin/bash
INPUT_DIR="./input"
OUTPUT_DIR="./output"
CRF=23

mkdir -p "$OUTPUT_DIR"

for file in "$INPUT_DIR"/*.mp4; do
    filename=$(basename "$file" .mp4)
    echo "Converting: $file"

    ffmpeg -i "$file" \
        -c:v libx265 \
        -crf $CRF \
        -preset slow \
        -c:a copy \
        -map_metadata 0 \
        -movflags use_metadata_tags \
        "$OUTPUT_DIR/${filename}_hevc.mp4"

    # Restore metadata
    exiftool -tagsFromFile "$file" "$OUTPUT_DIR/${filename}_hevc.mp4" 2>/dev/null
    touch -r "$file" "$OUTPUT_DIR/${filename}_hevc.mp4"
done

With Progress Display

#!/bin/bash
# Use pv or ffmpeg's -progress option for progress display

ffmpeg -i input.mp4 \
  -c:v libx265 -crf 23 -preset slow \
  -c:a copy \
  -progress pipe:1 \
  output.mp4 2>&1 | \
  while read line; do
    if [[ "$line" == *"out_time="* ]]; then
      echo "Progress: ${line#*=}"
    fi
  done

Encoding Quality Verification

VMAF Score Calculation

ffmpeg -i converted.mp4 -i original.mp4 \
  -lavfi libvmaf="model=version=vmaf_v0.6.1" \
  -f null -

PSNR/SSIM Calculation

# PSNR
ffmpeg -i converted.mp4 -i original.mp4 \
  -lavfi psnr="stats_file=psnr.log" \
  -f null -

# SSIM
ffmpeg -i converted.mp4 -i original.mp4 \
  -lavfi ssim="stats_file=ssim.log" \
  -f null -

Troubleshooting

QuickTime Compatibility Issues

# Add QuickTime compatible settings
ffmpeg -i input.mp4 \
  -c:v libx265 \
  -crf 23 \
  -tag:v hvc1 \
  -c:a aac \
  output.mp4

Preserve Color Space

ffmpeg -i input.mp4 \
  -c:v libx265 \
  -crf 23 \
  -color_primaries bt709 \
  -color_trc bt709 \
  -colorspace bt709 \
  output.mp4

Installing FFmpeg on macOS

# Using Homebrew
brew install ffmpeg

# Install with all codecs
brew install ffmpeg --with-libvpx --with-libvorbis

References