Cap Recording Benchmark Results

This document tracks performance benchmarks for Cap's recording system over time. Each benchmark run is timestamped, enabling comparison across different versions, configurations, and hardware.

Quick Reference

Performance Targets

Metric	Target	Tolerance
Frame Rate	30 fps	±2 fps
Frame Jitter	<15ms	-
Dropped Frames	<2%	-
A/V Sync (camera↔mic)	<50ms	-
Audio/Video Duration Diff	<100ms	-

Test Scenarios

Baseline: 5 second continuous recording
Single Pause: 3s record → 2s pause → 3s record (2 segments)
Multiple Pauses: 2s record → 1s pause → 2s record → 1s pause → 2s record (3 segments)

Running Benchmarks

bash

cargo run -p cap-recording --example real-device-test-runner -- baseline --keep-outputs --benchmark-output
cargo run -p cap-recording --example real-device-test-runner -- full --keep-outputs --benchmark-output

Benchmark History

Benchmark Run: 2026-01-28 11:42:54 UTC

Local time: 2026-01-28 11:42:54

Overall Result: ❌ FAILURES (0/6)

Notes: Fix #2: Display-Camera A/V sync - Sync display start time to camera/mic

Command: cargo run -p cap-recording --example real-device-test-runner -- full --keep-outputs

<details> <summary>System Information</summary>

Property	Value
OS	macos 26.2
Architecture	aarch64
CPU	Apple M4 Max
Display	5120x1440
Microphone	Shure MV7+
Camera	Camo Camera
Rust Version

</details>

Failed Tests:

Baseline (mp4+camera) — FRAME_RATE, AUDIO_TIMING
Baseline (fragmented+camera) — AUDIO_TIMING
Single Pause (mp4+camera) — FRAME_RATE, AUDIO_TIMING
Single Pause (fragmented+camera) — FRAME_RATE, AUDIO_TIMING
Multiple Pauses (mp4+camera) — DURATION, FRAME_RATE, AUDIO_TIMING
Multiple Pauses (fragmented+camera) — DURATION, FRAME_RATE, AUDIO_TIMING

<details> <summary>Detailed Results</summary>

❌ FAIL Baseline (mp4+camera)

Failure Tags: FRAME_RATE, AUDIO_TIMING

Metric	Result	Details
Segments	✅	1/1 expected
Start Times	✅	All segments near 0
A/V Sync	✅	tolerance: 50ms
↳ Seg 0 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
Duration	✅	5.11s/5.00s
Frame Rate	❌	expected 30fps ±2
↳ Seg 0 FPS	❌	28.7fps frames=147 dropped=4 (2.7%) jitter=10.6ms
	⚠️	Dropped frames exceed 2%
Audio Timing	❌	tolerance: ±100ms vs video
↳ Seg 0 Mic	❌	4.98s diff=136.8ms 48000Hz 1ch
↳ Seg 0 System	❌	4.89s diff=226.8ms 48000Hz 2ch

Elapsed: 6.32s

❌ FAIL Baseline (fragmented+camera)

Failure Tags: AUDIO_TIMING

Metric	Result	Details
Segments	✅	1/1 expected
Start Times	✅	All segments near 0
A/V Sync	✅	tolerance: 50ms
↳ Seg 0 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
Duration	✅	5.04s/5.00s
Frame Rate	✅	expected 30fps ±2
↳ Seg 0 FPS	✅	29.4fps frames=148 dropped=2 (1.3%) jitter=5.0ms
Audio Timing	❌	tolerance: ±100ms vs video
↳ Seg 0 Mic	✅	5.03s diff=12.7ms 48000Hz 1ch
↳ Seg 0 System	❌	4.92s diff=117.7ms 48000Hz 2ch

Elapsed: 5.89s

❌ FAIL Single Pause (mp4+camera)

Failure Tags: FRAME_RATE, AUDIO_TIMING

Metric	Result	Details
Segments	✅	2/2 expected
Start Times	✅	All segments near 0
A/V Sync	✅	tolerance: 50ms
↳ Seg 0 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
↳ Seg 1 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
Duration	✅	6.10s/6.00s
Frame Rate	❌	expected 30fps ±2
↳ Seg 0 FPS	❌	29.2fps frames=89 dropped=2 (2.2%) jitter=6.6ms
	⚠️	Dropped frames exceed 2%
↳ Seg 1 FPS	❌	29.2fps frames=89 dropped=2 (2.2%) jitter=8.4ms
	⚠️	Dropped frames exceed 2%
Audio Timing	❌	tolerance: ±100ms vs video
↳ Seg 0 Mic	✅	3.02s diff=30.2ms 48000Hz 1ch
↳ Seg 0 System	❌	2.91s diff=140.2ms 48000Hz 2ch
↳ Seg 1 Mic	✅	3.02s diff=33.5ms 48000Hz 1ch
↳ Seg 1 System	❌	2.91s diff=143.5ms 48000Hz 2ch

Elapsed: 9.23s

❌ FAIL Single Pause (fragmented+camera)

Failure Tags: FRAME_RATE, AUDIO_TIMING

Metric	Result	Details
Segments	✅	2/2 expected
Start Times	✅	All segments near 0
A/V Sync	✅	tolerance: 50ms
↳ Seg 0 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
↳ Seg 1 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
Duration	✅	6.06s/6.00s
Frame Rate	❌	expected 30fps ±2
↳ Seg 0 FPS	✅	29.5fps frames=89 dropped=1 (1.1%) jitter=5.5ms
↳ Seg 1 FPS	❌	28.9fps frames=88 dropped=3 (3.3%) jitter=12.1ms
	⚠️	Dropped frames exceed 2%
Audio Timing	❌	tolerance: ±100ms vs video
↳ Seg 0 Mic	✅	3.03s diff=14.9ms 48000Hz 1ch
↳ Seg 0 System	✅	2.92s diff=95.1ms 48000Hz 2ch
↳ Seg 1 Mic	✅	3.03s diff=13.8ms 48000Hz 1ch
↳ Seg 1 System	❌	2.88s diff=163.8ms 48000Hz 2ch

Elapsed: 9.10s

❌ FAIL Multiple Pauses (mp4+camera)

Failure Tags: DURATION, FRAME_RATE, AUDIO_TIMING

Metric	Result	Details
Segments	✅	3/3 expected
Start Times	✅	All segments near 0
A/V Sync	✅	tolerance: 50ms
↳ Seg 0 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
↳ Seg 1 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
↳ Seg 2 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
Duration	❌	3.78s/6.00s
Frame Rate	❌	expected 30fps ±2
↳ Seg 0 FPS	✅	29.7fps frames=59 dropped=0 (0.0%) jitter=1.1ms
↳ Seg 1 FPS	❌	29.3fps frames=44 dropped=2 (3.3%) jitter=10.4ms
	⚠️	Dropped frames exceed 2%
↳ Seg 2 FPS	❌	15.3fps frames=5 dropped=4 (6.7%) jitter=44.8ms
	⚠️	FPS outside tolerance
	⚠️	Jitter exceeds 15ms
	⚠️	Dropped frames exceed 2%
Audio Timing	❌	tolerance: ±100ms vs video
↳ Seg 0 Mic	✅	2.00s diff=18.2ms 48000Hz 1ch
↳ Seg 0 System	✅	1.91s diff=76.8ms 48000Hz 2ch
↳ Seg 1 Mic	❌	2.00s diff=501.5ms 48000Hz 1ch
↳ Seg 1 System	❌	1.91s diff=406.5ms 48000Hz 2ch
↳ Seg 2 Mic	❌	2.00s diff=1706.5ms 48000Hz 1ch
↳ Seg 2 System	❌	1.91s diff=1611.5ms 48000Hz 2ch

Elapsed: 9.16s

❌ FAIL Multiple Pauses (fragmented+camera)

Failure Tags: DURATION, FRAME_RATE, AUDIO_TIMING

Metric	Result	Details
Segments	✅	3/3 expected
Start Times	✅	All segments near 0
A/V Sync	✅	tolerance: 50ms
↳ Seg 0 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
↳ Seg 1 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
↳ Seg 2 Sync	✅	cam↔mic=0.0ms disp↔cam=0.0ms disp↔mic=0.0ms
Duration	❌	4.75s/6.00s
Frame Rate	❌	expected 30fps ±2
↳ Seg 0 FPS	❌	7.6fps frames=6 dropped=15 (25.0%) jitter=133.5ms
	⚠️	FPS outside tolerance
	⚠️	Jitter exceeds 15ms
	⚠️	Dropped frames exceed 2%
↳ Seg 1 FPS	❌	25.1fps frames=49 dropped=8 (13.3%) jitter=40.0ms
	⚠️	FPS outside tolerance
	⚠️	Jitter exceeds 15ms
	⚠️	Dropped frames exceed 2%
↳ Seg 2 FPS	❌	17.4fps frames=34 dropped=25 (41.7%) jitter=82.1ms
	⚠️	FPS outside tolerance
	⚠️	Jitter exceeds 15ms
	⚠️	Dropped frames exceed 2%
Audio Timing	❌	tolerance: ±100ms vs video
↳ Seg 0 Mic	❌	2.02s diff=1141.3ms 48000Hz 1ch
↳ Seg 0 System	❌	1.92s diff=1046.3ms 48000Hz 2ch
↳ Seg 1 Mic	✅	2.02s diff=70.5ms 48000Hz 1ch
↳ Seg 1 System	✅	1.92s diff=24.5ms 48000Hz 2ch
↳ Seg 2 Mic	✅	2.02s diff=83.0ms 48000Hz 1ch
↳ Seg 2 System	✅	1.90s diff=32.0ms 48000Hz 2ch

Elapsed: 9.18s

</details>

Analysis Guidelines

When analyzing benchmark results, focus on:

Regression Detection: Compare current results with previous runs to identify performance regressions
Pattern Recognition: Look for consistent failures across test types (e.g., always fails on fragmented output)
Environmental Factors: Note hardware differences, system load, or configuration changes
Root Cause Analysis: Use failure tags to identify which subsystem needs attention

Common Issues & Solutions

Issue	Possible Causes	Investigation Steps
Low FPS	Encoder bottleneck, CPU load	Check encoding timing metrics
High Jitter	Thread contention, GC pauses	Profile frame timestamps
Dropped Frames	Buffer overflow, slow encoding	Check pipeline metrics
A/V Sync Drift	Clock source mismatch	Verify timestamp alignment
Audio Gaps	Buffer underrun, device issues	Check audio stream continuity