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CROSS-FORMAT
MP4 to AU Converter — Free, Online, No Signup
Convert MP4 files to AU online with no signup required.
MP4 at a glance
MP4
MP4 grew out of the MPEG-4 and ISO Base Media File Format lineage, which helped make it both standards-based and commercially pervasive.
AU at a glance
AU
AU belongs to an earlier multimedia era where workstation and Unix vendors often had their own practical audio defaults.
Format comparison
| Feature | MP4 | AU |
|---|---|---|
| File type | Video | Audio |
| Extensions |
|
|
| MIME type |
|
|
| Created year | 2001 | 1987 |
| Inventor | ISO/IEC MPEG | Sun Microsystems |
| Status | active | active |
| Primary use cases |
|
|
| Multitrack support | Not supported | Not supported |
| HDR support | Not supported | Not supported |
| Streaming ready | Supported | Not supported |
When to use each format
When to use MP4
- Your source file is already in MP4.
- Preserve source expectations before exporting to AU.
- MP4 is commonly used in video workflows.
When to use AU
- Your target workflow expects AU.
- Improve delivery compatibility with AU.
- AU is commonly used in audio workflows.
FAQs
Why convert MP4 to AU?
Convert to AU when preserving compatibility with older Unix or workstation software, educational assets, or historical multimedia archives.
In most present-day workflows the practical task is to decode AU content and move it to WAV, AIFF, or a modern compressed format.
Use AU only when downstream compatibility makes it necessary.
What changes when converting MP4 to AU?
This conversion changes how the format behaves in downstream tools and delivery environments.
Moving to AU removes streaming delivery.
What should I review after converting MP4 to AU?
Validate output quality on representative files and confirm the target format behaves correctly in the destination workflow.