iplayer audio to lpcm

[Stuart Henderson]

On 2014/11/08 09:47, Jim Lesurf wrote:
> 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. :-) )

The projects are ffmpeg and libav (a fork of ffmpeg). One of the
libraries is named "libavcodec", the utility program is named "ffmpeg"
or "avconf".  In use, they should be pretty much interchangeable.

The utility is a swiss-army knife and can do conversions, audio/video
filters, mixing, etc, as you might expect there are a huge number of
options so it isn't always easy to track down some of the simpler
ones. Here are a few that might be of interest (in your case with
libav, use "avconv" instead of "ffmpeg"):

- extract audio and convert to pcm wav (default 16-bit unsigned)

ffmpeg -i infile -vn out.wav

- extract audio and convert to raw 24-bit signed

ffmpeg -i infile -f s24le -acodec pcm_s24le output.raw

(to see lists of other formats and codecs you can use here,
"ffmpeg -formats" or "ffmpeg -codecs").

- repackage audio+video from flv to mp4 file, no transcoding

ffmpeg -i infile -vcodec copy -acodec copy out.mp4

- repackage just the audio, no transcoding

ffmpeg -i infile -vn -acodec copy out.m4a