317 kbps radio files - really?

[Mable Syrup]

I'm getting the occasional, but increasingly more frequent, case where I end up with a file twice the size I'm expecting, and which claims to be 317 kbps.  I presume this is something at the BBC end, but what - and is there a solution/patch that I'm missing in my configuration? 

Example: this morning's Ken Bruce show weighs in at approx 374 Mb whereas yesterday's was around 149.


$ get_iplayer  --type=radio,tv  "ken b" --sin=8 --i | grep size
modesizes:      default: flashaaclow1=53MB,flashaacstd1=141MB,rtspaaclow1=53MB,rtspaacstd1=141MB,wma1=105MB

$ get_iplayer  --type=radio,tv  "ken b" --sin=8 --get --force
get_iplayer 2.86-2-g969bd34-ppa17, Copyright (C) 2008-2010 Phil Lewis
  This program comes with ABSOLUTELY NO WARRANTY; for details use --warranty.
  This is free software, and you are welcome to redistribute it under certain
  conditions; use --conditions for details.

Matches:
11614:	radio, Ken Bruce - Patrick Kielty chooses the Tracks of My Years, BBC Radio 2, Entertainment,Music,Radio

INFO: 1 Matching Programmes
INFO: Checking existence of default version
INFO: flashaacstd1,flashaaclow1 modes will be tried for version default
INFO: Trying flashaacstd1 mode to record radio: Ken Bruce - Patrick Kielty chooses the Tracks of My Years
INFO: File name prefix = Ken_Bruce_-_Patrick_Kielty_chooses_the_Tracks_of_My_Years_b0460sxj_default                 
RTMPDump v2.4-n78-git3a1e20c-ppa8~lucid
(c) 2010 Andrej Stepanchuk, Howard Chu, The Flvstreamer Team; license: GPL
Connecting ...
INFO: Connected...
Starting download at: 0.000 kB
INFO: Metadata:
INFO:   duration              9299.66
INFO:   moovPosition          36.00
INFO:   audiocodecid          mp4a
INFO:   aacaot                2.00
INFO:   audiosamplerate       44100.00
INFO:   audiochannels         2.00
INFO: tags:
INFO:   ©too                 Lavf54.29.104
INFO: trackinfo:
INFO:   length                410115072.00
INFO:   timescale             44100.00
INFO:   language              und
INFO: sampledescription:
INFO:   sampletype            mp4a
367179.551 kB / 9299.64 sec (99.9%)
Download complete
ffmpeg version git-N-30582-gef28c7b, Copyright (c) 2000-2011 the FFmpeg developers
  built on Jun  6 2011 15:24:53 with gcc 4.4.3
  configuration: --prefix=/usr --datadir=/usr/share/ffmpeg-extra --enable-static --disable-shared --enable-gpl --enable-version3 --enable-pic --enable-runtime-cpudetect --enable-bzlib --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libschroedinger --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --enable-decoder=aac --enable-decoder=aac_latm --enable-encoder=aac
  libavutil    51.  6. 0 / 51.  6. 0
  libavcodec   53.  6. 1 / 53.  6. 1
  libavformat  53.  2. 0 / 53.  2. 0
  libavdevice  53.  1. 1 / 53.  1. 1
  libavfilter   2. 14. 0 /  2. 14. 0
  libswscale    0. 14. 1 /  0. 14. 1
  libpostproc  51.  2. 0 / 51.  2. 0
[flv @ 0x93bd360] max_analyze_duration 5000000 reached at 5014000
[flv @ 0x93bd360] Estimating duration from bitrate, this may be inaccurate
Input #0, flv, from '/media/DATA/recordings/Ken_Bruce_-_Patrick_Kielty_chooses_the_Tracks_of_My_Years_b0460sxj_default.partial.m4a.flv':
  Metadata:
    duration        : 9300
    moovPosition    : 36
    audiocodecid    : mp4a
    aacaot          : 2
    audiosamplerate : 44100
    audiochannels   : 2
  Duration: 02:34:59.66, start: 0.000000, bitrate: N/A
    Stream #0.0: Audio: aac, 44100 Hz, stereo, s16
Output #0, ipod, to '/media/DATA/recordings/Ken_Bruce_-_Patrick_Kielty_chooses_the_Tracks_of_My_Years_b0460sxj_default.partial.m4a':
  Metadata:
    duration        : 9300
    moovPosition    : 36
    audiocodecid    : mp4a
    aacaot          : 2
    audiosamplerate : 44100
    audiochannels   : 2
    encoder         : Lavf53.2.0
    Stream #0.0: Audio: aac, 44100 Hz, stereo
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop, [?] for help
size=  366079kB time=02:34:59.66 bitrate= 322.5kbits/s    
video:0kB audio:360530kB global headers:0kB muxing overhead 1.539135%
INFO: Recorded /media/DATA/recordings/Ken_Bruce_-_Patrick_Kielty_chooses_the_Tracks_of_My_Years_b0460sxj_default.m4a

INFO: Downloaded Thumbnail to '/media/DATA/recordings/Ken_Bruce_-_Patrick_Kielty_chooses_the_Tracks_of_My_Years_b0460sxj_default.jpg'
INFO: MP4 tagging M4A file

 Started writing to temp file.
 Progress: =======================================================>100% |
 Finished writing to temp file.