TUAW reader Ryan B wrote us over the weekend, asking if we could confirm a behavior he’d observed when transferring files over iMessage.
“A friend and I noticed today that when you send .mp3 files through iMessage on Mac, the quality of the MP3 is downgraded.” He adds, “This appears to only happen with .mp3 files as .m4p’s are unaltered when received.”
Until now, I’d assumed that whatever data you sent using Messages arrived in basically the same form you sent it in. Apparently not.
We ran a few tests and this is what we found: most files arrive bit-for-bit identical compared to the files that were sent. But sure enough, MP3 files were downgraded considerably. The 5.12 MB stereo 228 kbps file I bought from Amazon was downgraded to 1.4 MB mono 62.4 kbps on receipt after transfer through Messages.
Why is this happening? We’re honestly not sure and I’d rather not speculate. We’ve reached out to Apple for comment but do not expect a reply.
The gallery that follows shows our results.
Gallery: Messages data transfer tests