iplayer audio to lpcm

[Jim Lesurf]

Prompted by the comments in another thread about transcoding, etc...

The main reason I've started experimenting with get_iplayer is to do some
comparisons of the audio which the listener gets via different routs
(iplayer versus Freeview / DTTV).

For DTTV I tend to either capture the transport stream using an HDTV dongle
(290e) or record onto DVR-RW. The DVD method tended to always mean some
transcoding or decoding to LPCM in the recorder. The dongle avoids that as
I get the transport stream.

For iplayer until now I've focussed on 'what the user hears' so have used
the standard BBC iplayer via FireFox, exported the resulting LPCM via USB
then on to recording the LPCM on a dedicated recorder. Around the houses,
but actually captures the LPCM being played out to hear. i.e. any flaws or
problems prior to emergence from the computer will be in the path.

What I'm hoping to do using get_iplayer is to be able to compare such
results with an analysis or decoding to LPCM of the flv by other means.
i.e. use ffmpeg or similar. I'm wondering if anyone else here has already
done this, or has comments that would help.

One complication here I've already hit is that IIUC the xfce mint distro
I'm using doesn't provide ffmpeg but avcodec (?) I've installed a local
version of ffmpeg but am unsure of how avcodec may differ from this in ways
that may affect what I have in mind. I'm used to ffmpeg, but not avcodec.
(Or have I got its name wrong? Afraid I've forgotten if my memory was ever
much better than nowdays. :-) )

Plan to do this both for R3 and for a suitable example or two from BBC
HDTV. Then write up any results for my website and HiFi News magazine. aim
being to help ensure people get the best possible sound. And if there's a
problem, alert those who may be able to check it.

FWIW If anyone is interested you can see similar sorts of projects on my
audiomisc site for other areas of audio. In the past I've been able to do
some comparisions, inc some comparing with 'source' files supplied by
people at the BBC to test the working of the 'pipeline' from the servers to
the output. But until now I've not been able to isolate and analyse any
effects due to the decoder used by the flash run by FF.

Jim

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