Transcoding occurs when you take a video source that has already been encoded, decodes it in an intermediate uncompressed format, then re-encodes it in the target format.
This process usually involves transmitting and image scaling (trans-sizing). Transratting is specifically concerned with changing the bitrate of a video viz. 8Mbps to 3Mbps. Image scaling is the process of changing the resolution of a video e.g. 4K to 720p.
Importance of Transcoding in Digital World
The telecommunications industry today, clearly, is widely different than it was 20 years ago – it is very different recently than it was five years ago. Mobile use has coincided with the worldwide adoption of smartphones and tablets, while VoIP and other IP communications are as common as landlines, perhaps even among people under 30.
Simply put, transcoding is the conversion of data from one format to another. More specifically, transcoding in VoIP is the conversion between one digital voice type, or codec, to another. This occurs when two communicating IP phones or end-point devices do not share a common codec.