Video Merger failed, stalled, or looks wrong? Troubleshooting
Troubleshoot Video Merger by codec, container, parameters, memory, and browser while respecting quality and device boundaries.
Do not rename an extension to fake a format
An extension names a container, not a guaranteed video/audio codec. Keep the source and record size, duration, codec, dimensions, browser, and exact error. Never overwrite the only original repeatedly.
The easy-to-miss issue for this tool
For mixed portrait and landscape clips, normalize canvas and frame rate first. Contain mode adds bars, and source loudness is not professionally matched.
Recommended troubleshooting order
- Load a very short, low-resolution known-good sample to confirm the tool starts.
- Check whether duration, video, audio, and dimensions are detected; missing metadata often means damage or an unsupported codec.
- Reduce duration, resolution, frame rate, or simultaneous file count.
- Close heavy tabs, retry in current desktop Chrome/Edge, and keep the page active.
- Reapply the workflow:
- Choose a small set of clips and drag them into order.
- Review duration, orientation, dimensions, and audio on each clip.
- Choose a common canvas, frame rate, and padding behavior.
- Inspect every join, audio level, and total duration after merge.
- If it still fails, use desktop FFmpeg or the producing application; do not claim browser support for that codec.
Parameter checks
- Order and enabled clips
- Common dimensions and background padding
- Frame rate and quality
- Silent-track handling for clips without audio
Common errors
Why are there black bars?
Different aspect ratios need padding when the complete frame is preserved.
Why does volume change at a join?
Sources have different levels and sample settings; professional loudness normalization is not included.
Are videos uploaded?
Media is read and transcoded in this browser tab and is not uploaded to FreeTool to perform the task.
Boundaries that cannot be bypassed
- Total size and browser memory make many long clips unsuitable
- Different clip properties normally require re-encoding
- No transitions, timeline, multitrack mix, or subtitle editing
Browser WASM lacks the full performance and codec set of native apps, and long video can take substantial time. A paused progress display does not mean server upload; processing is in the tab, but the browser can terminate it under memory pressure.
Privacy, rights, and open-source licenses
Media is read and transcoded in this browser tab and is not uploaded to FreeTool to perform the task. Troubleshooting images and outputs can still contain private, copyrighted, or hidden metadata. The ffmpeg.wasm wrapper is MIT and this release's FFmpeg core is GPL-2.0-or-later; source access and license notices must not be removed.