Apple Silicon VideoToolbox Hardware Acceleration Guide¶

Overview¶

This document covers hardware-accelerated HEVC encoding methods using VideoToolbox on Apple Silicon (M1, M2, M3, M4) Macs.

What is VideoToolbox?¶

VideoToolbox is Apple's low-level video encoding/decoding framework:

Provides hardware-accelerated video processing on macOS and iOS
Supports H.264, H.265/HEVC, ProRes, AV1 (M3+)
Accessible via hevc_videotoolbox encoder in FFmpeg

Feature Support by Chip Generation¶

Feature	M1	M2	M3	M4
H.264 Encode/Decode	✓	✓	✓	✓
HEVC Encode/Decode	✓	✓	✓	✓
ProRes Encode/Decode	✓	✓	✓	✓
AV1 Decode	✗	✗	✓	✓
ProRes RAW	✗	✓	✓	✓
10-bit HEVC	✓	✓	✓	✓

Additional Features in Pro/Max Chips¶

"Max chips have additional video encoding engines. VideoToolbox utilizes these extra engines even for a single transcoding session, supporting 4K 120fps transcoding." — Jellyfin Documentation

Performance Comparison¶

Software vs Hardware Encoding¶

Encoder	30s 4K Video Processing Time	File Size	Quality
libx265 (Software)	287s	Baseline	Best
hevc_videotoolbox	12s	+20-30%	Good

"On M2 Pro (10-core CPU/16-core GPU), VideoToolbox is 24x faster at 287s vs 12s." — b.27p.de

Simultaneous Transcoding Capability¶

"Even the entry-level M1 can handle three 4K 24fps Dolby Vision HEVC 10-bit transcoding jobs simultaneously." — Jellyfin Documentation

FFmpeg Commands¶

Basic Hardware Encoding¶

ffmpeg -i input.mp4 \
  -c:v hevc_videotoolbox \
  -q:v 50 \
  -c:a copy \
  output.mp4

Recommended Settings (Quality Priority)¶

ffmpeg -i input.mp4 \
  -c:v hevc_videotoolbox \
  -q:v 45 \
  -profile:v main \
  -tag:v hvc1 \
  -c:a copy \
  -map_metadata 0 \
  output.mp4

Quality Settings Guide¶

`-q:v` Option (1-100)¶

Value	Quality	Use Case
1-30	Highest	Archiving, original-grade
40-55	Recommended	General use
60-75	Medium	Storage savings
80+	Low	Not recommended

"hevc_videotoolbox quality 45-55 is the sweet spot. The default quality setting is not good." — Hardware Encoding Guide

Bitrate Settings (Alternative)¶

# Fixed bitrate (VBR is more recommended)
ffmpeg -i input.mp4 \
  -c:v hevc_videotoolbox \
  -b:v 10M \
  output.mp4

# Average bitrate
ffmpeg -i input.mp4 \
  -c:v hevc_videotoolbox \
  -b:v 8M \
  -maxrate 12M \
  -bufsize 16M \
  output.mp4

Software vs Hardware: Selection Guide¶

Hardware Encoding (hevc_videotoolbox) Recommended For¶

✅ Large batch conversions ✅ When fast processing is needed ✅ Near real-time conversion required ✅ When power efficiency matters (laptops)

Software Encoding (libx265) Recommended For¶

✅ Highest quality needed (archiving) ✅ Minimum file size needed ✅ No time constraints ✅ Advanced encoding options needed

Hybrid Approach¶

Step 1: Quick Conversion with Hardware¶

# First, fast hardware encoding
ffmpeg -i input.mp4 \
  -c:v hevc_videotoolbox \
  -q:v 40 \
  -c:a copy \
  quick_output.mp4

Step 2: Re-encode Important Files with Software¶

# High-quality software encoding for important files
ffmpeg -i input.mp4 \
  -c:v libx265 \
  -crf 20 \
  -preset slow \
  -c:a copy \
  high_quality_output.mp4

10-bit HEVC Encoding¶

10-bit Support on Apple Silicon¶

ffmpeg -i input.mp4 \
  -c:v hevc_videotoolbox \
  -profile:v main10 \
  -q:v 45 \
  output_10bit.mp4

Utilizing VideoToolbox Decoding¶

Hardware Decoding + Software Encoding Combination¶

# Hardware-accelerated decoding only (maintain best quality encoding)
ffmpeg -hwaccel videotoolbox \
  -i input.mp4 \
  -c:v libx265 \
  -crf 22 \
  -preset slow \
  output.mp4

Limitations and Considerations¶

Unsupported Options¶

Hardware encoders don't support all software encoder options:

❌ -preset (slow, medium, etc.) ❌ -tune ❌ -x265-params ❌ Some advanced GOP settings

File Size Trade-off¶

"In most cases, hardware encoding produces larger output files than software libraries. However, hardware encoding is much faster." — Martin Riedl

Quality Controversy¶

"Some users think VideoToolbox quality is lower (but it's incredibly fast)." — MacRumors Forums

Benchmark Script¶

#!/bin/bash
# Hardware vs Software encoding comparison

INPUT="test_video.mp4"

echo "=== Software Encoding (libx265) ==="
time ffmpeg -i "$INPUT" \
  -c:v libx265 -crf 23 -preset medium \
  -c:a copy \
  software_output.mp4 2>/dev/null

echo ""
echo "=== Hardware Encoding (VideoToolbox) ==="
time ffmpeg -i "$INPUT" \
  -c:v hevc_videotoolbox -q:v 50 \
  -c:a copy \
  hardware_output.mp4 2>/dev/null

echo ""
echo "=== File Size Comparison ==="
ls -lh software_output.mp4 hardware_output.mp4

FFmpeg Installation Verification¶

# Check VideoToolbox support
ffmpeg -encoders 2>/dev/null | grep videotoolbox

# Expected output:
# V....D hevc_videotoolbox    VideoToolbox H.265 Encoder
# V....D h264_videotoolbox    VideoToolbox H.264 Encoder