PrivateTools

trimy guide

Trim video without re‑encoding when the source allows it

Choose a range, inspect the available export path, and use stream copy only when its keyframe and compatibility limits fit the job.

Published Jan 10, 2025 · Updated Jul 30, 2026

6 minute guide

Open trimy

Result

What you will finish

  1. 01

    A reviewed start and end range

  2. 02

    A deliberate choice between Lossless and Precise

  3. 03

    A downloaded file checked in the destination player

Before you start

Check the source first

  • Lossless trimming is keyframe-aware; it is not guaranteed to begin on every exact frame.
  • Container names such as MP4 or MKV do not guarantee that stream copy is available.
  • Keep the source until the trimmed output has been checked for video, audio, and duration.

Procedure

Steps

The labels below match the current tool workflow. Export behavior still depends on the source files and browser capabilities.

  1. 01

    Load the source video

    Open the file from this device and wait for trimy to inspect it.

    Common containers include MP4, MOV, MKV, AVI, and WebM. Preview support, stream copy, and precise encoding depend on the codecs and timestamps inside the file.

    Local processing

    The source is read from this device. The page may download media runtimes, but the selected video is not uploaded to PrivateTools.

  2. 02

    Set the intended range

    Choose the section to keep with timeline handles or time inputs.

    • Scrub around the planned start and end points.
    • Play inside the retained range before exporting.
    • Use numeric time inputs when you need a repeatable boundary.
  3. 03

    Choose Lossless or Precise

    Use stream copy for speed, or encoding for exact boundaries and normalization.

    Lossless keeps the existing encoded stream when the source and cut boundaries allow it. Precise or Re-encode decodes and writes new media when you need an exact frame, crop, format change, timeline gap, or other transformation.

    • Lossless: fastest and preserves encoded packets, but follows usable keyframes.
    • Precise: use when the visual cut must land on an exact frame.
    • Re-encode: use for format normalization or a result that must play consistently in another app.

    Keyframe limit

    A lossless start point can move to a nearby keyframe. That is expected stream-copy behavior, not a frame-accurate edit.

  4. 04

    Choose the output

    Match the container and codec to the destination.

    MP4 with H.264/AAC is a practical compatibility target. WebM is useful for browser delivery, while MOV, MKV, or AVI may be appropriate when a specific downstream application requires that container.

    Copied quality

    Quality controls do not change copied packets. They matter only when some or all of the export is encoded again.

  5. 05

    Render and verify

    Download the result and inspect both cut boundaries.

    • Keep the tab open until the export finishes.
    • Check the first and last seconds of the downloaded file.
    • Confirm audio synchronization and playback in the destination app.

    Fallback

    If a copied result does not play reliably, use a compatible MP4 re-encode instead of repeating the same lossless export.

Questions

FAQ

01Does trimy upload my video?

No. The source file stays on your device. The app may download runtime components to your browser, but the video itself is not uploaded.

02When should I use Lossless vs Precise vs Re-encode?

Use Lossless for the fastest stream-copy cut or compatible join when it is available. Use Auto, Precise, or Re-encode when you need exact frames, mixed clips, timeline gaps, crop, or format normalization.

03Can trimy join videos without re-encoding?

Yes. Compatible clips can join with stream copy, preserving the encoded video. If only part of the sequence is incompatible, trimy can copy matching segments and re-encode only the mismatched clip, audio, or gap when that mixed path is available.

04Why does Lossless sometimes start a bit earlier or later?

Lossless cuts follow keyframes in the source. If the exact in-point falls between keyframes, switch to Precise or Re-encode.

05Can trimy trim very large videos?

trimy includes large-file paths for multi-GB sources, but practical limits still depend on available memory, browser storage, codec support, and the export method.

06Which browsers should I use?

Use a recent Chrome, Firefox, or Safari build. Codec support and WebCodecs acceleration depend on the browser and device, so trimy falls back to other local paths when needed.

Use Lossless for compatible cuts, not as a universal promise.

When exact boundaries or reliable playback matter more, choose the encoded path and verify the result.

Open trimy