Apple Lossless = major problems for iPod playback

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Charles D.
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Apple Lossless = major problems for iPod playback

Post by Charles D. » Sat Mar 04, 2006 9:54 pm

Firstly, profound thanks to the author and development team for Max. I was thrilled to find it on MacUpdate. My description of the problem is meant to help troubleshoot and improve Max.

I used Max to rip and encode as Apple Lossless. Apple Lossless was the only encoding format used (e.g. Max was not encoding at the same time to any other format). When I played the album on iTunes, two odd things happened, bothed fairly serious:

1. Dropouts (crackles, glitches, whatever you want to call them) were present in the majority of the songs on the album. They weren't subtle--kind of like the brief audio "skrtch" you get sometimes when your digital cable signal is bad.

2. The songs would not play in order. They listed in correct order when I opened the album in iTunes (e.g. the track number tags "1 of 8" "2 of 8" etc. were correct), and they were listed in the correct order when I started to play the album on the iPod, but the iPod would actually skip some songs and never play them. I could choose these songs and play them individually (usually with one of the glitches mentioned above at some point in the song).

I use a 60 Gb iPod Photo purchased in November 2005. I checked a couple of other albums that I ripped and encoded with iTunes, and they played correctly. I even pressed the center button and pause to reset the iPod, but that didn't make a difference. I also deleted the Max encoded album from the iPod, re-ripped and encoded it with Max while all other programs were closed (and no devices were connected to the computer running OS X 10.4.5), and then I copied that new rip to the iPod. Same problems (although the glitches were not in the same place).

So, I finally used Max to rip the songs and encode as AIFF. Then I imported the AIFF files to iTunes, added the tags, and converted to Apple Lossless with iTunes. I then deleted the Max encoded album from the iPod and copied over these new files to the iPod. Finally the album played normally with no glitches and the songs playing in order.

The ripping was the same and the tags were the same (although I had to add the AIFF tags by hand in iTunes), and the only difference was the Max encoding of the Apple Lossless files vs. the iTunes encoding of the Apple Lossless files.

Please let me know if I can provide additional information. It does appear to me that Max is having a problem producing good Apple Lossless files. I hope it can be sorted out, because this is primarily what I would like to use Max for since I don't much trust iTunes ripping.

P.S. I forgot to mention that the songs encoded to Apple Lossless with Max show up in iTunes with an "Unknown" bit rate. When I took the AIFFs ripped with Max and put them into iTunes, they showed up with the correct bitrate for uncompressed files (about 1400 kbps). And when they were encoded as Apple Lossless by iTunes they showed a bitrate of 700-800 kbps. Perhaps the fact that the Max-encoded Apple Lossless files are not reporting their bitrate correctly has something to do with the iPod playback problems?

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sbooth
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Post by sbooth » Sun Mar 05, 2006 9:34 am

There is a similar thread to this one here.

Also, regarding the missing bitrate tag, there was some discussion of that here (with additional information not totally germane here).

Unfortunately I'm not sure how to solve this issue- I did inquire on the Apple core audio mailing list and was told that the bitrate "issue" should not affect iPod playback. They also said that examples of lossless files that crash iPods should be submitted to http://bugreporter.apple.com, because the iPod should not crash even if given garbage files!

Charles D.
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Post by Charles D. » Tue Mar 07, 2006 11:44 pm

Thanks for the pointers to the other posts. I don't know if these files technically qualify as "crashing" the iPod. The iPod behaves strangely (skipping some songs when playing an album in sequence and playing glitches on some songs). I kind of figured that Max is invoking Core Audio encoding routines, so this would be hard to trouble shoot (one would expect that iTunes invokes Core Audio encoding also, so why the difference?).

I'll check out the other posts on this. One thing I haven't tried is different settings of Apple Lossless quality. I just used Maximum.

-Charlie

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sbooth
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Post by sbooth » Thu Mar 09, 2006 5:33 am

Charles D. wrote:I kind of figured that Max is invoking Core Audio encoding routines, so this would be hard to trouble shoot (one would expect that iTunes invokes Core Audio encoding also, so why the difference?).
I also originally assumed that iTunes uses CoreAudio for AAC/Apple Lossless, but I found out somewhat recently that it has its own AAC encoder. I believe it also has its own lossless encoder, but I am less sure on that one.

sbb
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Post by sbb » Thu Mar 09, 2006 11:08 am

Hi!!

I have a similar problem...

Using max 055 to encode with core audio to AAC (m4a) 160k best quality/VBR... those songs play fine on a 4G iPod but they just make my iPod shuffle crash...

I could not do tests (using other settings for the core audio AAC encoding)... but I believe this issue has something to do with this article: http://docs.info.apple.com/article.html?artnum=300590

As far as I understood itunes seems to be using Quicktime to encode to AAC or ALAC...

As you noticed Core Audio seems to offer a QT independent encoder... I suppose that compressor (software that comes with final cut pro) uses core audio as well to do its encodings (in FCP there's clearly a distinction between QT exports and compressor exports)...

what's interesting is that if you look at compressor settings for AACs you never have access to VBR settings...

So there's certainly something about QT encodings that make them more "compatible" with iPod chips...

What is interesting as well is that if you export songs from Toast 7 to AAC you have access to all those settings I love using core audio in MAX (quality levels for the sample rate converter, VBR, precedence and quality settings for the AAC encoder), choose the same options as in core audio (quality max, VBR / 160k) and they play fine on my shuffle (but display a constant bitrate in itunes, in opposition to core audio that shows an "real" average bitrate)... I suppose toast is using QT since it offers ogg Export through a QT plugin I installed...

hope that information helps...

CG
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Post by CG » Sat Apr 22, 2006 5:06 pm

After some testing, I have noticed the same thing.

Here's what I tried:

1. Max rip > ALAC encode > copy into iTunes > iPod

2. Max rip > AIFF encode > copy into iTunes > iPod

3. Max rip > AIFF encode > copy into iTunes > convert to ALAC > iPod

4. iTunes > ALAC encode inside iTunes > iPod

CD read Error checking was enabled in all. Same CD. As same everything as I could make it. All the files were copied into my iPod Photo 60G through iTunes.

For case #1, the first track played just fine. At the end, instead of the usual short delay for the buffer to fill, there was about a five second delay. The track title was still displayed on the screen. Then the name of the second track was shown for a second or less, then the title of the third track appeared. No sound from track #2, but everything continued normally from then on, at least until track #4 - same kind of thing.

There was normal and expected behavior for all three other cases. In addition, when playing these tracks back through iTunes on the Mac, everything acted normally. This was using the iPod as the source, not the library (to be sure I cleared these tracks from the iTunes library.)

I *think* this suggests that the ripping process is fine, but that there is some kind of flaw in the mp4 container surrounding the ALAC encoded files generated by Max. Something in the data must be telling the iPod the wrong thing.

I've noticed this on more than one CD. It's repeatable, too, in the sense that the same tracks seem to get skipped regardless of what the iPod was doing previously. That again suggests something inherent to the mp4 file generated by Max rather than some buffer getting filled. BTW, the files for all the ALAC's were the same size, so that kind of rules out the buffer.

I *wish* I could offer some insight to the inner workings of these files to help, but this is my limit...

oblomov
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Apple Lossless Files & iPod Crashes

Post by oblomov » Tue Mar 27, 2007 5:01 am

Noticed thread has been dormant for past year. Wondering about further developements as experiencing same (Apple Lossless files play for 2~3 seconds then cause iPod to lock-up / crash / freeze; necessitating manual reboot).

Software:
Mac OS X 10.4.9
QuickTime 7.1.5
iTunes 7.1.1(5)
Max 0.7.1

Hardware:
3rd Generation iPod (20GB)
iPod v2.3 software

Workflow:
FLAC file --> Apple Lossless using Max (Format: 'AAC ADTS', Source: 'Core Audio') --> iTunes --> iPod

Can verify tracks ripped to Apple Lossless format directly from CD using iTunes do not cause playback issues on iPod.

Can verify that Apple Lossless files created using Max do report bit rate information correctly in iTunes information window (ranging from low 200 to mid 800).

Apple Lossless files created using Max play normally in iTunes.

If issue has not been resolved, is there a method to force iTunes to re-parse the Max generated files without degrading the files?

Thanks!

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sbooth
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Post by sbooth » Tue Mar 27, 2007 5:05 am

Are you truly encoding to AAC ADTS? It should be MPEG-4 Audio for the iPod...

oblomov
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Post by oblomov » Tue Mar 27, 2007 6:16 am

Yes... it is the first format option (under 'Setup output formats') that generates an Apple Lossless file with the .m4a extension. It was also listed under 'Desired output formats' correctly as 'MPEG4 Audio (Apple Lossless). iTunes seemed happy with it so I figured that's the ticket. Obviously not!

Took an album that I had originally converted to Apple Lossless using 'AAC ADTS' and ran the problem files back through Max using the 'MPEG4 Audio (Apple Lossless)' format and got briefly excited as the first track on the album plays fine on the iPod... but on selecting the second track the iPod either locks up or reboots on its own. After playing successfully once the first track on the album will not play correctly a second time.

Tried converting the AAC ADTS file --> FLAC --> MPEG4 Audio (Apple Lossless) hoping that would shake the problem. Same results as above.

Will try some other conversion paths tomorrow.

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