[PATCH] Output AAC as M4A for iTunes with metadata tags (Shevek)

[Jon Davies]

On 31 March 2011 14:35, richard <richard at richsim900.plus.com> wrote:
>
> Sorry to spoil things, but the patch to ffmpeg has not solved the
> problem with my Marantz CD6003. These are the tests I've done.
> ...snip

We seem to have established that ffmpeg isn't generating entirely
valid mpeg4 files, I wonder does it work if you pipe it through MP4Box
on the way? thus:

ffmpeg -i "Bells_on_Sunday_-_27_03_2011_b00zq9t8_default.flv" -acodec
copy -absf aac_adtstoasc temp.m4a
MP4Box -add temp.m4a:mpeg4 -sbr -ipod Bells-on-Sunday.m4a
AtomicParsley Bells-on-Sunday.m4a --artist "BBC Radio 4" --title
"Bells on Sunday" --overWrite

... though if this works I'd be reluctant to advocate adding another
program dependency to get_iplayer - I'd be inclined to consider it a
workaround.

I don't have an ipod and itunes to hand, but for a test file I do have
here mp4info reports different things. note the kbps in the audio
track...  it suggests (as I think we're establishing) that ffmpeg
mangles the metadata atoms in a way that makes them inconsistent with
what's actually in the file.  The ffmpeg patch did something in the
textual metadata, it looks like there's another bug in the atom(s)
that describe the audio stream.

ffmpeg-current aac -> m4a:
mp4info version 1.6
Classic_Chandler_2._The_Lady_in_the_Lake.m4a:
Track   Type    Info
1       audio   MPEG-4 AAC LC, 5400.102 secs, 0 kbps, 44100 Hz
 Name: Classic Chandler: 2. The Lady
 Artist: BBC Radio 4
 Tool: Lavf52.94.0
 Year: 2011
 Album: Saturday Play
 Comment: Derace Kingsley, a wealthy bus

MP4Box raw aac -> m4a:
mp4info version 1.6
foo2a.m4a:
Track   Type    Info
1       audio   MPEG-4 AAC LC, 5400.032 secs, 128 kbps, 44100 Hz

MP4Box raw aac -> m4a followed by AtomicParsley to add a couple of tags:
mp4info version 1.6
foo2b.m4a:
Track   Type    Info
1       audio   MPEG-4 AAC LC, 5400.032 secs, 128 kbps, 44100 Hz
 Name: Classic Chandler: 2. The Lady in the Lake
 Artist: BBC Radio 4