Keep the pictures or keep only the sound?
Free MP3 Cutter Joiner cuts and joins audio and can prepare audio from supported local video files. It does not save a joined MP4, a visually edited movie or a frame-accurate video cut. If your deliverable includes the picture, start with a video editing workflow.
The articles below explain when a timeline export is useful and when compatible encoded video might be copied. Each guide includes official documentation for the separate tools it discusses.
Pick the operation you need
Join MP4 videos in order Trim video and understand quality Compare smart and frame-accurate cuts Keep selected segments and remove the restCheck a short result before a long export
Use a small representative clip to check order, visible boundaries, sound sync and playback on the destination device. Different cameras, codecs and stream layouts can change what a copy-based operation can do. Keep the original and choose the method based on the checked result.
When you only need a listening file, follow the audio guides rather than trying to produce a video with an audio-only tool.
Prepare audio from a local video Browse audio cutting and joining guides