MP4, WebM, M4A and MP3 formats explained
A file extension describes a container or audio format, not a promise of quality. Resolution, codec and bitrate still matter. The downloader shows the extension supplied or prepared for the selected item.
Quick comparison
| Format | Contains | Best use |
|---|---|---|
| MP4 | Video and usually audio | Broad compatibility with phones, browsers, TVs and editors. |
| WebM | Video and audio, or one stream | Modern web playback; device support varies. |
| M4A | Audio only | Efficient audio used by many phones and players. |
| MP3 | Audio only | Very broad compatibility, with lossy compression. |
Combined video and video-only streams
A source may expose one MP4 that already contains sound, or separate high-resolution video and audio streams. Download Video Online marks the available option and, for supported YouTube qualities, prepares one MP4 by merging the matching streams. A video-only file will be silent unless combined with audio.
Downloading audio
The YouTube to MP3 tool extracts a public video’s audio and prepares a 192 kbps MP3. The SoundCloud downloader keeps the accessible audio source, which may be M4A. A bitrate label describes the output stream; it cannot reconstruct detail missing from the original.
Which format should you choose?
- Choose MP4 for a video that should play almost everywhere.
- Choose M4A when the source provides audio and your player supports it.
- Choose MP3 when audio-only compatibility matters more than avoiding conversion.
- Do not convert repeatedly between lossy formats: every conversion can lose more detail.
File names and extensions are sanitized before download. Always keep the correct extension so the operating system can select an appropriate player.