They were optimized for slow 2G and 3G cellular speeds.
Delivered much clearer video at smaller file sizes, enabling the first wave of mobile HD streaming.
It was the standard video format for feature phones made by Nokia, Sony Ericsson, Motorola, and BlackBerry.
In the early days of the mobile internet, watching a video on a phone was a major technical challenge. Today, we stream high-definition (HD) and 4K content instantly over 5G networks.
Audio was heavily compressed using the AMR (Adaptive Multi-Rate) codec, which made sound tinny and muffled.