I believe that Freesat bitrate is 192kbps which is very low. The best bitrate can be obtained via ffmpeg command line from the BBC webstream up to 369kbps, which is as good as it gets for lossy webstreams. When the programme is finished, get_iplayer will download at 322 kbps but the best trick I have found is to download from the iplayer using a YouTube-dl command line. This gives an AAC file in mp4 container, which when converted to a "transport" stream container (ts), shows a bitrate of 366 kbps