Format of BBC Radio 4 .m4a files

RS richard22j at
Mon Sep 14 10:27:37 PDT 2015

Thanks for the suggestion.  I didn't manage to install the 
mp4file --optimize program in Ubuntu, but I did find a similar program for 
mp4box -hint
It splits the file into 500ms segments and writes the header information at 
the beginning of each segment.  I had a 45min program which seemed to make 
the Longevity player freeze for about 4min.  The hinted file didn't make the 
player freeze or delay.  It immediately skipped to the next file and did not 
play anything.

mp4box -hint did report an error.
[ODF] Error reading descriptor (tag 6 size 16): Invalid MPEG-4 Descriptor

I was sent two small files each about 90s, one .m4a as downloaded from the 
BBC and the other after running mp4file --optimize.  Neither caused any 
freezing or delay, so that may only occur with larger files.  With both the 
player immediately skipped to the next file without playing anything.

Playing aac/.m4a files does seem to be problematic.  At one time the iPod 
Shuffle 2 would not play files from some versions of Nero.

On Friday, September 11, 2015 12:32 PM Jon Davies wrote:

>On 9 September 2015 at 11:05, RS <richard22j at> wrote:
>> If I try to play the BBC Radio 4 .m4a files in the Longevity player the 
>> player freezes for about 4min.

>I recall hearing about similar behaviour with someone's mp3 player -
>it appeared that the player was reading through the entire file to
>read some metadata at the end before actually playing the audio
>stream.  I don't beleive that the m4a files that come out of iplayer
>are optimised for streaming, and I believe that some of the metadata
>is at the end of the file.  So it's possible that your player is
>having a similar problem.

>On ubunutu I use "mp4file --optimize" to optimize each m4a file that
>pops out of get_iplayer, there are other programs that do similar
>things.  You could try this and see if it solves your problem, and if
>it does it's possible to write a script that get_iplayer runs after
>each download to do this every time.


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