Radio File Format Questions

[Vangelis forthnet]

On Sun Jul 14 13:44:55 BST 2013, Chris Marriott wrote:

>What do we get if we use the "aactomp3" flag on "get_iplayer"? That's the
>way that I've always done it personally, and the results are entirely
>satisfactory (to my ear) for spoken word programmes (which are all I ever
>download).

Hello Chris!

>From GiP's "longhelp" (get_iplayer --longhelp) I quote:

Recording Options:
 --aactomp3  Transcode AAC audio to MP3 with ffmpeg (CBR 128k 
unless --mp3vbr is specified)
 --mp3vbr   Set LAME VBR mode to N (0 to 9) for AAC transcoding. 0 = target 
bitrate 245 Kbit/s, 9 = target bitrate 65 Kbit/s (requires --aactomp3)

that is if you are downloading a "flashaac" radiomode (no matter if it is 
the low/std variant) and you have
specified the --aactomp3  switch, you will end up with an .mp3 audio file 
transcoded @ 128kbps
constant bitrate (CBR).
If it is the flashaaclow mode you are recording (which I find is sufficient 
for spoken word content), then
with --aactomp3 you do have the original quality preserved, but at a 2.6 
times the original file size (=128/48).
In such a case I would experiment with the --mp3vbr switch at values larger 
than 7, which will produce
smaller mp3 files - beware though that some hardware (/ portable) mp3 
players are "peaky" about VBR
files; they may report wrong duration or not play the mp3 file at all...
If it is the flashaacstd mode (default from within the UK) you are 
recording,  --aactomp3 produces a same size
(to the initial .aac source) audio file, with no noticeable loss of quality 
for spoken content. This is not the case
for Radio 3 content, please also refer to my post earlier in the month:

http://lists.infradead.org/pipermail/get_iplayer/2013-July/004425.html

And I will repeat myself, but only transcode if you really have to!

Now, as far as the OP (Budgie) is concerned, the way I understood it is that 
he has already on disk some
"flashaaclow" audio files that have presumably expired (so he cannot 
re-download them using the --aactomp3
switch) but needs to listen to them on his Network Player that does not 
support the encoding format of the files
(HE-AACv2 = AAC+SBR+PS). In order to do this, he must re-encode them to a 
format supported by his Player...
I hope I made things clearer now :-)

Vangelis.