Automatic conversion of aac to m4a

[dinkypumpkin]

FWIW, using ffmpeg with "-absf aac_adtstoasc" doesn't work in my environment (OSX + iTunes + 5th gen iPod + ffmpeg v0.6.1).  The resulting m4a file will import into iTunes, but it won't play (not on iPod either), and the duration shown is completely wrong, so I surmise there is still some crud left in the data.  Output from mp4info shows 0 kbps bitrate in the m4a files, which seems fishy as well, though ffmpeg -i reports an appropriate value.  I notice Shevek appeared to be testing on Windows, so perhaps this is down to some difference between platforms or ffmpeg builds.  If any other Mac users can contribute more data points, please chime in.

However, Nick's mp4box solution does work for me.  I've tried 20 different AAC downloads of radio programmes, and all worked perfectly with mp4box, while none worked with ffmpeg alone.  Of course, ffmpeg is still required to convert the FLV download file to AAC input to mp4box.  I agree that a ffmpeg-only solution would be desirable, but I couldn't get it work on my Mac.  For whatever reason, only mp4box can repackage the AAC stream appropriately for iTunes.

One suggestion for Nick: I think mp4box needs "-new" in its argument list so that it will overwrite the m4a file, or else there should be explicit handling of "--overwrite" arg.  Otherwise, mp4box will add a track to the existing file.


On 14 Mar 2011, at 09:45, Nick Ludlam wrote:

> Aha, that would make it much more simple. I'll have a look at that this evening, thanks Shevek.
> 
> On 14 Mar 2011, at 09:42, <shevek at o2.co.uk> <shevek at o2.co.uk> wrote:
> 
>> Why introduce a new tool into get_iplayer? 
>> 
>> Ffmpeg can do this already. 
>> 
>> See my post [1] for details
>> 
>> I agree with the --m4a option but I think it should use ffmpeg
>> 
>> Just my 2p 
>> 
>> Shevek
>> 
>> [1] http://lists.infradead.org/pipermail/get_iplayer/2011-March/000948.html