m4a still problematic on 5G ipod video (30GB)

[btodd]

search of the forums showed people experiencing problems on various players in 2006, but no reports of issues in 2007. however, I am experiencing issues with playing m4a files on the ipod itself. the files play normally through winamp. I believe they were created from source w dbpoweramp, but it might have been itunes (I know, I know).

running r16912-071211 now, but issue has been persistent through several previous builds. I'm just too lazy to reconvert and it's just a few hundred files out of 7000+, but it would be nice to get it fixed.
thanks

[saratoga]

Can you confirm that they are AAC-LC ?  I don't know how to check in winamp, but foobar will display the AAC profile under its properties option (look for the field "Codec Profile").  AAC-HE, AAC-PS and the other exotic formats cannot be played on the iPod due to the slow CPU.

[Lear]

You would increase the chances of getting any problems fixed if you could describe the problems in some detail. Just saying you're "experiencing issues" doesn't say much...

[EricRoss]

I've been having a problem with m4a files on my ipods for a while now as well. Usually m4a files in my playlist are just skipped and it moves on to the next song, but sometimes it gets stuck and won't play anything. When that happens, I can select a new song to play but nothing will play until I reboot it (regardless of the file type).
It's been bothering me because I know that I used to play m4a files in Rockbox without any problems and the same files play correctly on my computer.

After seeing this thread, I decided to look into the code. I found a comment towards the bottom of mp4.c that says, "Rockbox currently doesn't support metadata after the mdat atom". Running the program mp4creator (it's part of the mpeg4ip package) with the -optimize option fixed my m4a files and now they play correctly in Rockbox again.

I've been adding tags to my files with easytag recently and I suspect that's when they stopped playing correctly in Rockbox. Some evening when I have more time I'll look into patching the code to support files like these. In the meantime, hopefully this info will help others use their m4a files in Rockbox.

[Lear]

Note that adding support for m4a files with the metadata at the end isn't a small and quick fix. The reason is that the decoder, which only reads buffered data, need access to some of the metadata before starting to decode. Having a decoder start a track by seeking to the end of the file and then back again could cause gaps between tracks and unnecessary disk spin-ups.

[EricRoss]

I figured that there was a good reason for it to be written this way since it appeared to be by design. I just didn't know what that reason was. It's really not a big deal now that I know why they wouldn't play and have a solution to fix the files.

[walterk]

If you have the solution, can you share it? I'm ready to give up on rockbock over this issue. this seems to be a recent issue - it worked before. is there a version i can revert to that worked?

[saratoga]

If you have the solution, can you share it? I'm ready to give up on rockbock over this issue. this seems to be a recent issue - it worked before. is there a version i can revert to that worked?

Check 3 posts above yours.

[walterk]

sorry - the replies mean nothing to me. is this a problem that can be fixed? is there a older version that works?

[EricRoss]

Sure it can be fixed but the problem lies within the m4a files and not Rockbox. I used the utility mp4creator to fix the m4a files on my linux workstation. You can try the following line at a command prompt to fix your music files.
  mp4creator -optimize yoursong.m4a
Then copy the song to your Rockbox player and it should play without a problem.

[walterk]

Thank you. I'll give it a try.