You should record audio at the best quality you can manage, using a lossless file format (like .wav)
When it comes to sharing your audio as a podcast, MP3 and M4A files are the only audio filetypes that are supported for podcast apps (like iTunes or Apple Podcasts). Acast Open supports both file formats.
We recommend uploading 128 - 160kbps MP3 files. These typically have the right balance of good audio quality and small size, which your listeners will appreciate.
Acast Open does not change the quality of the files you upload.
What are the limits?
Most people use the Apple Podcasts app to listen to podcasts. Apple has set the file limit to 150MB for all files downloaded over a cellular connection (including apps, ebooks, and videos). When your listeners try to play your episode, they are greeted with a pretty unhelpful message—"episode unavailable"—which is a frustrating experience to say the lease. To help our podcasters avoid this issue, Acast Open sets the internal limit to 150MB also.