Cut HEVC

How to Cut an HEVC File Online

1. Upload Your HEVC File: Drag and drop or click "Add Files" to select a .hevc raw elementary stream — exports from FFmpeg's hevc_mp4toannexb/extract_extradata filters, x265 CLI output, NVIDIA NVENC/AMD AMF dumps, Intel Quick Sync samples, codec test vectors, and IP-camera Annex B byte streams all work. Containerized H.265 (.mp4, .mkv, .mov, .ts) is also accepted and the H.265 elementary stream is extracted automatically. Batch is supported — drop in multiple .hevc files at once.
2. Set Start Time and Duration: Enter a start time and a duration to keep. Both fields accept seconds (12.5) or HH:MM:SS.sss format (00:00:30.500) for millisecond precision. Add multiple cut segments to extract several non-contiguous regions from the same bitstream in a single pass — useful for pulling specific GOPs out of a long test vector.
3. Pick Output Mode (Optional): Default keeps the original H.265 stream — a stream-copy that writes the cut Annex B NAL units verbatim with zero re-encoding. The output is bit-identical to that range of the source, including VPS/SPS/PPS parameter sets and SEI messages. Switch to re-encode if you need frame-accurate cuts or a codec change: H.264 (universal playback), AV1 (~30% smaller than HEVC at equivalent quality), VP9, MPEG-4, or HEVC at a new bitrate. Pair with a resolution preset (2160p, 1440p, 1080p, 720p, 480p, percentage, or custom width/height) and a quality preset (Highest → Lowest), CRF slider (18 = visually lossless, 23 = default, 28 = smaller), constant bitrate, or target file-size percentage.
4. Cut and Download: Click Cut. Files process in your browser session — download individually or as a ZIP. No sign-up, no watermark, no length cap on the output. The output keeps the .hevc extension and stays Annex B by default.

Why Cut a Raw HEVC Stream?

A .hevc file is the raw HEVC/H.265 elementary stream in Annex B byte-stream format — NAL units prefixed with 0x000001 startcodes and no container around them, per the ITU-T H.265 / ISO/IEC 23008-2 spec, Annex B. That format is what x265, NVENC, the FFmpeg hevc_mp4toannexb bitstream filter, and most IP-camera pipelines emit. Cutting a .hevc file at the byte level preserves every NAL unit untouched, which is what codec engineers, regression-test authors, and broadcast pipelines need. Common reasons to cut a raw HEVC bitstream:

• Codec regression testing and bug isolation — When an HEVC decoder hangs, crashes, or produces visual artefacts on frame 3,847, cutting a 50-frame window around that frame gives you a 200 KB repro case to attach to a bug report instead of a 4 GB original. Stream-copy preserves the exact NAL boundaries the decoder fault depends on.
• Conformance and test-vector trimming — JCT-VC and AOMedia reference test vectors are often multi-GB; teams routinely cut representative sub-sequences (one IDR period, one B-pyramid, one tile-partitioned slice) for unit tests and CI fixtures.
• FFmpeg / GStreamer pipeline analysis — Engineers debugging a transcode chain often dump raw .hevc after hevc_mp4toannexb to inspect NAL units in HEX. Cutting to the suspect range lets HEVC ES Viewer, gpac, or 265dump load the file in seconds.
• IP-camera and surveillance review — Reolink, Hikvision, and Dahua cameras commonly export Annex B .hevc per-channel. Cut the 15-second window of an incident out of an 8-hour recording without re-encoding the whole feed.
• Broadcast and remux extraction — Engineers pulling HEVC payloads from MPEG-TS or DASH segments work with raw Annex B by default. Cutting in the Annex B domain avoids a round-trip through a container and back.
• Sharing developer repro clips — A 5-second HEVC cut at 1080p is typically under 5 MB, which fits under Discord's 10 MB free upload cap (dropped from 25 MB in April 2024), Gmail's 25 MB inline cap, and most GitHub-issue attachment limits.

If you need the cut wrapped into a playable container afterwards, run it through HEVC to MP4 or HEVC to MKV. For the timeline-editor experience without the raw-bitstream framing, see Trim HEVC, or Compress HEVC for size-only reduction.

Stream Copy vs Re-encode — When to Use Which

Property	Stream copy (default)	Re-encode
Speed	Seconds for any size, including 50 GB UHD remuxes	Proportional to clip length
Quality	Bit-identical to source HEVC NAL units	Slight loss unless CRF 18-20
Cut precision	Snaps to nearest IDR/CRA keyframe	Frame-accurate
VPS / SPS / PPS parameter sets	Preserved exactly	Rewritten by encoder
SEI messages (HDR10, HDR10+, DV RPU, timecode)	Preserved	May be dropped unless explicitly carried
10-bit / 12-bit Main10 / Main12 profiles	Preserved bit-perfect	Preserved if encoder supports
Output codec	Stays H.265 / HEVC, stays Annex B	H.264, H.265, AV1, VP9, MPEG-4, etc.
Best for	Repro clips, test vectors, HDR sources, fast cuts	Frame-accurate edits, codec change for compatibility

Stream-copy can only start the output at an IDR (Instantaneous Decoder Refresh) or CRA (Clean Random Access) NAL unit, because that's the first frame a decoder can independently reconstruct. Most camera and screen-capture HEVC uses a 1-2 second GOP, so the cut snaps to within 1-2 seconds of your requested timestamp. Low-bitrate IP-camera encoders sometimes push GOPs out to 5-10 seconds; check with ffprobe -show_frames if you need to predict the exact snap point.

HEVC Profile / Source Cut Reference

Source	Typical GOP	Profile / bit depth	Cut style
x265 CLI output (--keyint 250)	~10 sec at 25 fps	Main / Main10	Stream copy; long GOPs mean coarse snap
FFmpeg hevc_mp4toannexb dumps	Matches source GOP	Whatever source uses	Stream copy preserves source NALs
NVENC / AMF / QuickSync HEVC	1-2 sec	Main / Main10	Stream copy
IP-camera Annex B (Reolink / Hikvision)	2-10 sec	Main	Stream copy; verify GOP first
UHD Blu-ray remux extract	1-2 sec	Main10, HDR10 / HDR10+ / DV	Stream copy preserves HDR metadata
Apple ProRes / iPhone capture transcoded to .hevc	1-2 sec	Main / Main10	Stream copy
JCT-VC reference test vectors	Varies (often 8-32 sec)	Main / Main10 / Main12 / 4:2:2	Stream copy preserves conformance

Frequently Asked Questions

Does cutting a .hevc file re-encode the bitstream?

No, not in the default stream-copy mode. XConvert parses the Annex B NAL units, locates the IDR or CRA before your start time, and writes the contiguous range of NAL bytes into a new .hevc output. No HEVC decode, no HEVC encode, no quality loss — the output bytes within the cut range are identical to the corresponding bytes in the source. This is critical for codec testing, where re-encoding would mask the exact bug you're trying to capture. Re-encoding only happens if you opt in via step 3 (to change codec, resolution, or bitrate).

Will the VPS, SPS, and PPS parameter sets be carried into the cut output?

Yes. Stream-copy writes the activated VPS/SPS/PPS NAL units at the start of the output so the cut decodes standalone — you don't need the original file to play it. If the source uses in-band parameter sets (common with Annex B) they're preserved verbatim; if it uses out-of-band parameter sets (less common for raw .hevc) they're inserted in-band so the cut is self-contained. SEI prefix messages (HDR10 mastering display, HDR10+ dynamic metadata, Dolby Vision RPU, picture timing) are also carried.

Why does my cut start a second or two earlier than the timestamp I entered?

HEVC stream-copy can only start the output at an IDR or CRA keyframe — those are the only NAL units a decoder can independently initialise from. The cut therefore snaps to the nearest preceding IDR/CRA. Most NVENC/AMF/QuickSync output uses a 1-2 second GOP so the snap is within 1-2 seconds; x265 with --keyint 250 at 25 fps uses ~10-second GOPs so the snap can be up to 10 seconds off. To predict it, run ffprobe -show_frames -select_streams v <file> | grep key_frame=1. For exact-frame cuts, enable re-encode in step 3 and pick CRF 18-20.

What's the difference between .hevc, .h265, and .265?

All three are conventional extensions for raw HEVC Annex B elementary streams — same byte format, different naming preferences. FFmpeg writes .hevc by default; some tools and reference encoders write .h265 or .265. None of them carry audio, subtitles, or timing — there's no container. If your file has audio or chapters it's almost certainly inside .mp4, .mkv, .mov, or .ts instead; XConvert auto-detects and extracts the H.265 elementary stream from any of those.

Will HDR10, HDR10+, and Dolby Vision metadata survive the cut?

Yes, in stream-copy mode. HDR10 static metadata (Mastering Display Colour Volume + Content Light Level SEI), HDR10+ dynamic tone-mapping SEI, and Dolby Vision RPU NAL units all travel inside the HEVC elementary stream — stream-copy doesn't touch the bytes, so HDR playback works on the same TVs, Apple TVs, and Plex/Infuse clients that handled the source. Re-encoding HDR HEVC is risky: most browser encoders strip Dolby Vision RPU or remap to SDR unless metadata is explicitly carried, so stream-copy is the safe default for HDR.

Can I cut a 10-bit Main10 HEVC bitstream?

Yes, transparently. Stream-copy is bit-depth-agnostic — it doesn't decode samples, so 8-bit Main, 10-bit Main10, 12-bit Main12, and 4:2:2/4:4:4 chroma profiles all pass through unchanged. The output bit depth and chroma sampling match the source exactly. This matters because some online tools silently downconvert Main10 to 8-bit; XConvert's stream-copy mode cannot, by design.

How do I get the cut to play in QuickTime, Windows Media Player, or a browser?

Raw .hevc Annex B is a developer/analysis format — most consumer players won't open it directly because there's no container, no audio track, no duration metadata, and no MOOV box. Once you've cut the bytes you need, run the output through HEVC to MP4 or HEVC to MKV to wrap it in a player-friendly container. Windows 10/11 also needs Microsoft's HEVC Video Extensions codec ($0.99 in the Microsoft Store) for built-in playback; free alternatives are VLC, MPV, and PotPlayer.

What's the maximum .hevc file size I can cut?

There's no fixed cap. Cutting runs in your browser session, so the practical limit is your device's available memory and patience for the upload. Multi-GB encoder dumps and 50-80 GB UHD Blu-ray HEVC extracts both work — stream-copy is fast enough that an 80 GB source finishes the cut in under a minute once it's loaded, because no transcoding happens. For sources larger than your RAM, consider pre-cutting with ffmpeg -i in.hevc -c copy -ss ... -t ... out.hevc locally.

Can I cut multiple non-contiguous segments from the same .hevc file in one pass?

Yes. The trim controls accept multiple segments — add a second range (start + duration) and the cut concatenates both regions into one output .hevc. Each segment still has to start at an IDR/CRA in stream-copy mode, and the parameter sets are reactivated between segments so the result is a single self-contained bitstream. Useful for extracting specific test ranges (e.g., the IDR period containing frames 0-30 plus the one containing frames 1000-1030) into a single regression fixture.

Should I cut the raw .hevc or cut the containerised MP4/MKV instead?

Cut in whichever domain you'll consume the output in. If your downstream tool (codec analyser, conformance checker, NAL dumper) wants raw Annex B, cut the .hevc directly. If you need a playable file with audio and timing, work from the MP4/MKV — see Trim HEVC for the container-aware workflow, or cut here and run HEVC to MP4 on the output. Avoid round-tripping: cutting MP4 → demuxing to .hevc → re-cutting Annex B is wasted work that risks SEI loss at the container boundary.