Merge videos and audio files

How joining works

The joiner plays each file through in the order of the list and writes them one after another into a single new file. Drag the rows to set the order. Videos and audio files are joined separately: a list of videos becomes one video, a list of audio files becomes one audio file. A mix of both cannot be joined, since there would be nothing to show while the audio plays.

Every clip is encoded again, which is what lets clips from different phones, cameras and apps, with different sizes, frame rates and formats, end up in one consistent file. The cost is time, and a small loss of quality compared with the originals.

Clips of different shapes and sizes

The finished video has one size for all its clips. By default it takes the size of the first video; choose Up to 1080p, 720p or 480p to cap it. Clips of another shape, such as a vertical phone video next to a landscape one, are fitted in one of two ways:

• Fit with bars shows the whole clip, with black bars at the sides or top and bottom. Nothing is cut off.
• Fill and crop fills the frame and trims what overflows, from the centre. No bars, but the edges of the clip are lost.

Put the clip whose shape you want first: the whole video takes its size. To make every clip the same shape before joining, use the crop option of the video converter.

Quality, sound and format

• Quality: Balanced, the default, aims for 5 Mbps, which suits 1080p video for sharing. High and Very high keep more detail for editing; Small file suits phones and messaging.
• MP4 plays everywhere; WebM suits web pages.
• Clips without sound leave a silent gap for their length, so the sound of the following clips stays in time with their picture.

For audio, MP3 plays everywhere, M4A sounds a little better at the same bitrate, and WAV is uncompressed for further editing. 192 kbps, the default, suits music; 128 is plenty for speech.

Before you join

Trim each clip first with trim video, since cutting the joined file later means encoding it again. Joined videos are often large; to fit a size limit for sending, run the result through compress video. For audio, the audio cutter can also join clips from one file.

If something goes wrong

• It says to add only videos or only audio. The list mixes both. Join them separately, or remove one kind.
• A clip has black bars. Its shape differs from the first video. Choose Fill and crop, or put a clip of the right shape first.
• A clip cannot be decoded. The browser does not support its codec, as with HEVC on some systems. Convert that clip first, or try another browser.