Format of BBC Radio 4 .m4a files

Jim web web at
Fri Sep 11 10:37:37 PDT 2015

In article
<CAJEH5C3hnMfJsWYci2EYrz1Wi-2uh823aqHaaMjLP6Weu07f3A at>, Jon
Davies <jon at> wrote:
> On 9 September 2015 at 12:28, Jim web <web at> wrote:
> > Why not flac?

> because as others have pointed out, the raw data downloaded from the bbc
> is aac.  you can't improve the quality by removing compression, 

I can't recall saying otherwise.

> all this will do is occupy more space on your disk.  All get_iplayer
> does by default is re-package the (unchanged) aac data in an mp4 file.

Yes. For the avoidance of doubt I should add that I did know that. :-)

> If you ask get_iplayer for mp3 then whether it was built to transcode
> directly from the original aac or via flac would make no difference
> whatsoever.

I think you've misunderstood the point of my question. Alas you've
also now removed the context so I have to add it back in the following..

If your player can't play the mp4a and you *need* to transcode the basic
choice is simple. You either:

A) transcode to some other 'lossy' format like mp3. This will be almost
certain to lose details.


B) transcoder to a loss-free format like flac (or lpcm wave). This can be
done with *no* loss of details.

You've now snipped the context which was that mp4a wasn't playable on the
player. That's the basis of the discussion.

So, because "leave it as mp4a" is taken not to be a useful option by the
conditions of the situation, the above choice may be unavoidable in the
circumstances. OTOH if you *can* play mp4a then obviously no transcoding is
necessary (except during replay).

So the point of my question was to find out if there was a reason why, *in
this situation where mp4a won't play*, you can't (or don't wish to) choose
flac. (B) allows the user to avoid more loss, not wave a wand to recover
what wasn't present in the mp4a.


Armstrong Audio
Audio Misc

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