Audio-only files on video platforms
An .aac file cannot be posted on YouTube, Instagram or TikTok, and many messengers show it as a generic attachment that people never open. Turning it into an MP4 video changes that. An MP4 with a picture plays inline in chats, appears in social feeds, and is accepted by every video site. People convert AAC to MP4 to share a voice message, a recorded song, a lecture clip, a radio segment or a sound captured on a phone.
Picture and animation
- Image: a photo, cover art, a logo or a slide from your device.
- Colour: a single background colour for a clean look.
- Gradient: two colours of your choice, with the title and artist on top.
- Waveform or spectrum: an optional animation that reacts to the sound, so viewers see that the video is playing.
Pick the format for the platform
| Choice | Size in pixels | Use it for |
|---|---|---|
| 1080p | 1920 x 1080 | YouTube and widescreen viewing |
| 720p | 1280 x 720 | smaller files, faster rendering |
| Square | 1080 x 1080 | feed posts on Instagram and Facebook |
| Vertical | 1080 x 1920 | TikTok, Reels, Shorts, WhatsApp status |
Audio quality in the video
MP4 videos store their sound as AAC, so the audio stays in the same codec family. It is encoded once more during rendering. With a source of 128 kbps or more, the change is very hard to hear, and video platforms will re-encode the sound anyway after upload. Low-bitrate AAC from voice apps stays as clear as it was, but will not sound fuller.
A still image adds very little to the file size; a three-minute video with a static picture is often only a few megabytes bigger than the AAC. Animated waveforms add more data because every frame is different. Rendering runs on your own device, so long files take longer on phones. Raw AAC has no tags, so give the video a title when you upload it.
Before you render
Trim silence at the start and end with Cut audio, and raise quiet recordings with normalize so the video is not too soft on phones. For more layout options, open audio to video. If you want a plain audio file that plays everywhere instead, convert AAC to MP3.