AAC audio: MP3 transcoding as backup option

[dinkypumpkin]

On 17 Mar 2011, at 02:03, Vangelis forthnet wrote:

> Thank you dinkypumpkin for sharing your version :-) I am using get_iplayer on Windows Vista Home Premium SP2 x86 & I am facing the problem of getting untagged mp3 files from get_iplayer. I have searched the net laboriously to find a Windows 32bit static executable compiled from sources for id3v2 CLI (http://id3v2.sourceforge.net/), but so far no luck.

Binaries do seem scarce on the ground, but I found a copy here:

http://discotag.googlecode.com/svn-history/r26/trunk/tools/id3v2.exe

It works for me on WinXP SP3.  For the resulting files, VLC shows all frames, iTunes doesn't show comments (ID3v1.1 or ID3v2),  Winamp and WMP 11 show the ID3v1.1 comments.  I think this is due to how the comments are written in get_iplayer.  It includes a content description for the COMM frame ("Description:" prefix in id3v2 invocation), and some players (e.g., iTunes) will only show a COMM frame with empty content description as the "comments" field, while others (Winamp and WMP) appear to fall back to the ID3v1.1 frame.

The binary referenced above is v0.1.10, and I think they're up to 0.1.12 now, but I would guess the old version is still OK for these purposes.  If that binary doesn't work for you, start another list thread on the topic.  I know of 2, possibly 3, alternatives to id3v2, and I'm sure there are more.  The next time I'm need of serious procrastination I might have a crack at doing a new build, but I don't spend much time in Windows.

> no --aactomp3 option: flv [demuxed-> ] aac [remuxed->] m4a (tagged with AtomicParsley)
> --aactomp3 option: flv [demuxed-> ] aac [transcoded->] mp3 (untagged for me, tagged with id3v2 when available)

Slight correction: with the --aactomp3 option, the flv is transcoded directly to mp3

> Can you please, for the benefit of Windows users, modify your script and create e.g. an --m4atomp3 option so that the transcoding occurs after the creation of the m4a file:
> --m4atomp3  option: flv [demuxed-> ] aac [remuxed->] m4a (tagged with AtomicParsley) [transcoded->] mp3 (tag intact)

There should be no need for this now, and I'm not convinced it's a good idea, anyway.  I think it would depend on how good ffmpeg is at translating MP4 atoms to ID3 frames.  Based on a quick test with ffmpeg+iTunes+VLC, it doesn't seem to work well enough.  The comments and description get shoved into TXXX frames and thus won't appear in most players, the artwork disappears (no surprise there), and iTunes doesn't translate the release date frame into a release year.  Others may have better ffmpeg-fu and know some may to get better fidelity.