Scripts

Transcode benchmarks

Proof-of-concept benchmarks for real-time VOD transcoding: transcode a video file with FFmpeg (optionally with hardware acceleration) and measure time and throughput. Used to de-risk the real-time VOD transcoding feature (segment-level transcode + cache): we need ~10s segments to transcode in well under 10s (ideally <2s) so timeline scrubbing stays responsive.

Python (recommended)

From the repo root:

# Full file, CPU
python scripts/transcode_benchmark.py path/to/recording.mp4

# First 10 seconds only (simulates one HLS segment)
python scripts/transcode_benchmark.py path/to/recording.mp4 --duration 10

# 10s segment with NVIDIA HW accel
python scripts/transcode_benchmark.py path/to/recording.mp4 --duration 10 --hwaccel nvidia

# Simulate scrubbing: start 60s in, transcode 10s (VAAPI)
python scripts/transcode_benchmark.py path/to/recording.mp4 --duration 10 --seek 60 --hwaccel vaapi

# Intel QSV H.265 (preset-intel-qsv-h265)
python scripts/transcode_benchmark.py path/to/recording.mp4 --duration 10 --hwaccel qsv-h265

# Custom FFmpeg binary (e.g. Frigate container)
python scripts/transcode_benchmark.py path/to/recording.mp4 --duration 10 --ffmpeg /usr/lib/ffmpeg/7/bin/ffmpeg

Options:

--duration SEC – Transcode only this many seconds (default: full file). Use 10 to simulate one HLS segment.
--seek SEC – Start at this position (fast seek before -i). Simulates scrubbing into the file.
--hwaccel cpu|nvidia|vaapi|qsv-h265 – Matches Frigate presets: libx264, h264_nvenc, h264_vaapi, preset-intel-qsv-h265 (hevc_qsv).
--vaapi-device – VAAPI device (default: /dev/dri/renderD128).
--qsv-device – Intel QSV device: on Linux defaults to /dev/dri/renderD129 if present (else renderD128, else 0). With two GPUs, the second node is often the Intel iGPU. Override if you get “No VA display found” (e.g. try the other node).
--output PATH – Write output here (default: temp file, deleted).
--keep-output – Keep the temp output file.

Output: real time, speed (× realtime), output size. The script suggests whether the speed is good for ~10s segment transcode.

Shell

Quick one-liners without Python:

chmod +x scripts/transcode_benchmark.sh

./scripts/transcode_benchmark.sh path/to/recording.mp4
./scripts/transcode_benchmark.sh path/to/recording.mp4 10
./scripts/transcode_benchmark.sh path/to/recording.mp4 10 nvidia

Arguments: INPUT [DURATION_SEC] [cpu|nvidia|vaapi|qsv-h265]. Optional env: FFMPEG, FFPROBE, VAAPI_DEVICE, QSV_DEVICE.

Interpreting results

Speed ≥ 5× realtime – A 10s segment transcodes in ~2s or less; good for on-demand segment transcode with cache.
Speed 1–5× – Marginal; segment may take several seconds; transcode-ahead or caching helps.
Speed < 1× – Too slow for real-time; consider stronger HW or lower resolution/bitrate.

Run with a real Frigate recording (or any H.264/HEVC MP4) and try both --duration 10 and full file to see segment vs full transcode cost.

Troubleshooting `qsv-h265` (“No VA display found”)

Intel QSV (qsv-h265) only works on Intel GPUs with a working Intel VA-API stack. If both /dev/dri/renderD128 and renderD129 fail with “No VA display found” or “Device creation failed: -22”, then:

Check which GPUs you have – With two cards, both may be non-Intel (e.g. NVIDIA + AMD). QSV is Intel-only. Use lspci -k | grep -A3 VGA to see adapters and drivers.
Check VA-API – Run vainfo or vainfo --display drm --device /dev/dri/renderD128 (then renderD129). If it errors or shows no Intel driver, QSV won’t work. On Intel you typically need intel-media-driver (newer) or intel-vaapi-driver (i965, older).
Permissions – Ensure your user is in the render (and often video) group: groups; add with sudo usermod -aG render $USER and log in again.
Use another HW accel – If you have an AMD GPU, use vaapi (H.264). If you have NVIDIA, use nvidia. Otherwise use cpu.
Frigate Docker uses QSV but host benchmark fails – The container has the Intel VA/QSV stack and device access; the host may not. Run the benchmark inside the same environment (e.g. inside the Frigate container):
```
# Copy script and a sample recording into the container (adjust container name)
docker cp scripts/transcode_benchmark.sh frigate:/tmp/
docker cp /path/to/59.24.mp4 frigate:/tmp/
docker exec -it frigate bash -c 'chmod +x /tmp/transcode_benchmark.sh && /tmp/transcode_benchmark.sh /tmp/59.24.mp4 10 qsv-h265'
```
The script auto-detects FFmpeg under /usr/lib/ffmpeg/*/bin when ffmpeg isn’t on PATH (Frigate container). If it doesn’t, set FFMPEG and FFPROBE explicitly, e.g. docker exec ... env FFMPEG=/usr/lib/ffmpeg/7.0/bin/ffmpeg FFPROBE=/usr/lib/ffmpeg/7.0/bin/ffprobe /tmp/transcode_benchmark.sh ....

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