How to transcode 4k masters to h.265 for long-term archive
- Step 1Decide your archival bitrate — Archive favours quality headroom over the smallest file. For 4K, 20–40 Mbps HEVC preserves most detail; go higher if the footage is grain- or motion-heavy and you want a near-transparent master.
- Step 2Open on a hardware-capable device with Pro + Media — The 100 GB streaming ceiling and hardware path require Pro + Media. Use a Mac (VideoToolbox) or a Chromium browser on a PC with NVENC/AMF/Quick Sync. Make sure the File System Access API is available so output streams to disk.
- Step 3Drop the 4K master — MP4, MOV, MKV, WebM, AVI, M4V, TS are accepted. The source must be browser-decodable — standard 8-bit H.264/HEVC is; some 10-bit/odd-profile masters may not load.
- Step 4Set the bitrate (kbps) for your quality target — Type the kbps (×1000 internally): 20000 ≈ 20 Mbps, 40000 ≈ 40 Mbps. Leave at
0only if a high resolution-based ceiling is acceptable — for 4K that ceiling is very high. - Step 5Set framerate explicitly for non-30fps masters — If your master is 24, 25, 50, or 60 fps, enter it. Left at
0, JAD keeps the source cadence but assumes 30 fps for its frame-count estimate when it can't read the real rate. - Step 6Stream to disk and handle the audio — Pick a save location; output streams there as
<name>-h265.mp4. Because it's video-only, re-attach the master's audio before filing it, or keep the original alongside as the audio source.
4K storage: H.264 vs HEVC
Approximate per-hour storage at common 4K bitrates. The point of an HEVC archive is the right-hand column.
| Codec / bitrate | Per hour | Per 10 hours |
|---|---|---|
| 4K H.264 @ 60 Mbps | ~27 GB | ~270 GB |
| 4K HEVC @ 40 Mbps (high archival) | ~18 GB | ~180 GB |
| 4K HEVC @ 30 Mbps (balanced) | ~13.5 GB | ~135 GB |
| 4K HEVC @ 20 Mbps (lean) | ~9 GB | ~90 GB |
| Saving vs H.264 60 Mbps | — | up to ~3× less |
Archival bitrate guidance (4K HEVC)
Pick higher for grain/motion-heavy masters you want to keep near-transparent. Set kbps in the bitrate field.
| Content | Suggested kbps | Character |
|---|---|---|
| High-motion / grainy master | 40000 | Near-transparent, larger |
| General 4K footage | 30000 | Balanced archival quality |
| Low-motion / interview / screen | 20000 | Lean, still detailed |
| Auto (0) | resolution ceiling | High for 4K — set explicitly for predictable size |
Archive-relevant behaviour
What an archivist needs to know before treating the output as a master.
| Aspect | Behaviour |
|---|---|
| Audio | NOT carried through — output is video-only |
| Framerate | Source cadence; assumes 30 fps if unreadable — set it |
| Output container | MP4 (-h265.mp4) |
| Streaming to disk | Yes on Pro + Media (100 GB ceiling) |
| Quality model | Bitrate (no CRF, no lossless mode) |
| 10-bit / HDR | Not a controllable feature of this tool |
Cookbook
Archival 4K transcodes with bitrates that preserve detail — and the audio handling you can't skip for a master.
Balanced 4K archive at 30 Mbps
A sensible default for a general 4K master: roughly half the storage of a 60 Mbps H.264 original, with quality that holds up for re-use.
Input: master-4k.mp4 (4K, H.264 ~60 Mbps, 1h)
~27 GB
Fields: Bitrate (kbps) = 30000 Framerate = 24
Output: master-4k-h265.mp4 (~13.5 GB, video-only)
Streamed straight to your chosen archive folder.Near-transparent master for grainy footage
Film grain and high motion cost bits; give the encoder headroom so the archive doesn't smear detail you may want to grade later.
Input: drama-4k.mov (grainy, high motion) Fields: Bitrate (kbps) = 40000 Framerate = 25 Why high: no CRF here, so headroom = bitrate. Output: drama-4k-h265.mp4
Lean archive for interview / screen-capture 4K
Low-motion 4K compresses extremely well in HEVC. You can drop the bitrate hard without visible loss.
Input: interview-4k.mp4 (static framing) Fields: Bitrate (kbps) = 20000 Framerate = 30 Output: interview-4k-h265.mp4 (~9 GB/hour)
Re-attach audio to make a real master
An archive master with no audio is rarely acceptable. The encode is video-only, so plan the audio step explicitly.
After encode: master-4k-h265.mp4 (SILENT) Keep the original as the audio source, or build a master with audio using a size/bitrate path that keeps it: /video-tools/video-bitrate-set (video + audio kbps) Note: that path is software (libx264), not HW HEVC.
Batch a folder of 4K masters overnight
Queue many masters in one job (Pro + Media up to 50, Developer unlimited). They encode sequentially through the hardware path and stream out.
Drop: master_001.mp4 ... master_050.mp4 Fields: Bitrate (kbps) = 30000 Framerate = 0 Each -> master_NNN-h265.mp4 (video-only) Processed in sequence; outputs stream to disk.
Edge cases and what actually happens
Archive master has no audio
By designThe hardware HEVC path is video-only, so the output has no sound — usually unacceptable for a master. Keep the original alongside as the audio source, or build the master with a software path that preserves audio such as video-bitrate-set.
Wrong framerate recorded in the archive
Set fpsWhen Framerate is 0 and the browser can't read the true rate, JAD assumes 30 fps for its estimates. For 24/25/50/60 fps masters, set the framerate explicitly so the archived cadence is correct.
10-bit / HDR master flattened
Not supported hereThis tool exposes only bitrate and framerate — there's no HDR/10-bit control. Treating a 10-bit HDR master as a true archive copy through this path isn't appropriate; preserve the original or use a dedicated HDR-aware workflow.
Source won't load (10-bit / odd profile)
Load failsSome 10-bit or unusual-profile 4K masters can't be decoded by the browser "<video>" element. Transcode to a browser-friendly MP4 first with the video-transcoder.
Very large 4K file on limited RAM
OOM riskEven with streaming output, decode + encode of a huge 4K source is memory-hungry. Use a desktop with ample RAM and a hardware encoder; phones will OOM on large 4K.
No hardware HEVC encoder
Encode failsOn Firefox or a GPU without HEVC encode the run fails fast. For software 4K HEVC (slower) use the video-transcoder with codec H.265 and a CRF for quality-targeted archival.
Auto bitrate produced a huge 4K file
Set it lowerAuto's resolution ceiling is very high at 4K. For a predictable archive size, set the bitrate explicitly (20000–40000 kbps depending on content).
Free or Pro plan
Upgrade requiredThe 100 GB streaming ceiling and hardware path are Pro + Media features. Lower tiers can't run the 4K archive flow.
Need smaller still for cold storage
Consider AV1If your hardware can encode AV1 (RTX 40-series, Arc, M3+), it's ~30% smaller than HEVC again — attractive for cold archive. See the av1-encoder.
Frequently asked questions
How much storage will I actually save?
Roughly half versus 4K H.264 at matched quality, sometimes up to 3× less than a heavily over-bitrated 60 Mbps H.264 master. Across a 10-hour library at 30 Mbps HEVC you go from ~270 GB to ~135 GB. The exact saving depends on the bitrate you target and the footage.
Is HEVC a good choice for an archive master?
For storage-efficient archive of 4K, yes — it preserves quality at half the bitrate. The caveats for a true master: this tool is video-only (handle audio separately), it has no 10-bit/HDR control, and quality is bitrate-targeted not CRF. For maximum fidelity you may prefer to keep the original or use a dedicated mastering codec like ProRes (see the prores-encoder).
Why has my archive master no sound?
The hardware HEVC encode path doesn't carry the audio track into the output. For a master, that's usually a problem — keep the original as the audio source, or build the file with a path that preserves audio such as video-bitrate-set (which is software libx264, not HW HEVC).
What bitrate should I use for 4K archive?
Archive favours headroom: 30000 kbps (30 Mbps) is a balanced default, 40000 for grain/motion-heavy footage you want near-transparent, 20000 for low-motion content. There's no CRF, so the bitrate you set is your quality control.
Can it handle a 100 GB master?
On Pro + Media the per-job ceiling is 100 GB and output streams to disk, so the file doesn't have to fit in memory. The real constraint is your device's RAM during decode/encode — use a capable desktop, not a phone.
Does the 4K encode run fast?
On hardware that supports HEVC encode, near real-time — the GPU's video block does the work. Software 4K HEVC (the video-transcoder's libx265 path) is much slower but offers CRF if you need it.
Will it preserve HDR or 10-bit?
This tool exposes only bitrate and framerate — there's no HDR or 10-bit control, so don't rely on it as a faithful copy of a 10-bit HDR master. Preserve the original for HDR-critical archives.
Can I batch a whole folder?
Yes — Pro + Media allows up to 50 files per job and Developer is unlimited. They encode sequentially through the hardware path and each streams to disk as <name>-h265.mp4.
Is anything uploaded?
No. Decode, encode, and mux all happen in the browser tab; masters never leave your machine. Only an anonymous usage counter is recorded server-side.
My 4K source won't load — why?
It's likely a 10-bit or unusual-profile file the browser can't decode in a video element. Convert it to a standard 8-bit MP4 first with the video-transcoder, then archive to HEVC.
Should I use AV1 for cold storage instead?
If your hardware can encode AV1 (RTX 40-series, Intel Arc, Apple M3/M4), AV1 is about 30% smaller again at the same quality and royalty-free — a strong fit for cold archive. See the av1-encoder. Decoder support for AV1 is also broader than HEVC in modern players.
What plan do I need for the 4K archive flow?
Pro + Media. That's where the hardware-encode pipeline and the 100 GB streaming-to-disk ceiling live. Free and Pro see an upgrade prompt.
Privacy first
Every JAD Video tool runs entirely in your browser via WebCodecs and FFmpeg (WebAssembly). Your video files never leave your device — verified by zero outbound network requests during processing.