Discussions (& strategies) on getting WMA and M4A (AAC) decoding in real-time.

[Davide-NYC]

I wanted to start this thread to have a single place on the forum for folks to discuss the state of the WMA decoder and the M4A--AAC decoder.

I own an iRiver H1x0 and neither of these decode in realtime as far as I know.

Decoding these two very common formats is very, very important for Rockbox in my opinion. I want to support this effort any way that I can. (I can't code very well, but I can help in other ways)

This could be the place where Dev X says: "I'm tackling file blah.x, please someone do the following otherwise Dev Y can't finish with that other thing." (Or something along those lines)

Maybe if the devs coordinate and 'divide-and-conquer' the code in an efficient way? I dunno...

I'm just trying to start up a discussion on strategy to best tackle this beast of a problem.

Basically what I'm saying is Rockbox with WMA and M4A decoding would be absolutlely crushing.  Crushing!  

[LinusN]

One problem with that might be that many developers don't read this forum. Most hard-core developer discussions are held in the mailing list and the IRC channel.

[patwa]

I agree with the OP wholeheartedly.  I wish my iPod running rockbox could play .wma files, m4a files as well now I come to think of it. A lot of music is in those formats, and at the moment it wn't play.  Keeping a copy of dbPowerAmp on the iPod is all well and good, but not much use when you need to connect to a computer to be able to re-encode and convert the music.

Yep, so I agree with the sentiment.

Hussein.

[Davide-NYC]

One problem with that might be that many developers don't read this forum. Most hard-core developer discussions are held in the mailing list and the IRC channel.

What about a Twiki page? If this is a good idea then what should it contain to begin with?

I am imagining a table with all the lib files in one column and the volunteer/assignee in the next, followed by comments and then the state of 'optimization'.

I've been told that ASM optimization is CPU dependant, but I presume that for now we're only talking about two targets: Coldfire and  the DualARM7 targets.

Can we reach out to other OSS project working on audio playback on fixed point targets? IpodLinux maybe? Are there any others?

At this point I'm just littering this thread with my thoughts hoping that some of this is deemed to be a good idea. I'm willing to do the wretched clerical work on this one. I don't speak C very well and my ASM is zero, so I'll contribute any other way that I can.

Discuss!  

[Mmmm]

Well... my MP4 files now play nicely in realtime!! \o/

[RonH]

http://forums.rockbox.org/index.php?topic=6613.msg51884#msg51884

[Davide-NYC]

WOW! My M4A are playing now without skipping. Granted I only have 128kbps and simlar VBR encoded M4A, but hell, they work!

My M4As at 128kbps boost at 60% while my MP3s at 192kbps boost only at 3% on my H140.  So the M4A codec is not yet fully optimized but a great stride forward has been taken. Thanks!

Sweetness. 0.5 down! 1.5 to go! Rockbox rules.  

[Suicide_Guy]

Way to go guys on getting the .m4a codec working. I love you guys. Now all we need is the .wma codec and I will love you like no other! When .wma works, then I shouldn't ever have to switch back to the OF.

[JonathanHull]

Any tips on getting iTunes bought AAC songs working? DRM has been stripped via QTFairUse but they still won't play in my H120.

[Llorean]

Have you tried it on other things that refuse to play DRMe'd AACs?

[JonathanHull]

Mplayer and Xine both play it, and FAAD is able to decode it to wav.

[Llorean]

I guess that just falls under the "Our AAC decoder is still far from perfect" clause then.

[JonathanHull]

Thats what I thought. OK guess I'll just keep using the transcoded files for now.

Thanks.

[saratoga]

Mplayer and Xine both play it, and FAAD is able to decode it to wav.

Thats odd since our AAC decoder IS FAAD.  Maybe you could try stripping off all tags and/or repacking the stream in an MP4 container in case the problem is with the parser.

[JonathanHull]

Mplayer and Xine both play it, and FAAD is able to decode it to wav.

Thats odd since our AAC decoder IS FAAD.  Maybe you could try stripping off all tags and/or repacking the stream in an MP4 container in case the problem is with the parser.

I was thinking the same thing.

I stripped the DRM with an older version of QTFairUse, so it might not have done it right but it worked fine in Mplayer so I figured it worked.

So those files don't play, doesn't give an error and just keeps moving on to the next file in the playlist/dir.

Next I tried "dumping" the raw AAC from the file with faad and the -a swithc (I think, don't remember exactly). These files did the same thing if I remember correctly.

Next I tried repacking these files with mp4creator, and these files just crashed rockbox. However, I had some problems with it due to running mp4creator in wine since I'm on Linux. I may try booting my windows box back up and trying this again on there to see if it works better, or maybe upgradding QTFairUse and restripping the DRM.

I'll get back with my results later.

Thanks for the help.