[audioengr]

A Customer of mine has been doing a lot of experiments for me to determine the best-possible computer playback, both at 44.1 and upsampled to 24/96.

His early testing with 44.1 tracks showed that ALAC files streamed WiFi to an AirPort Express or Apple-TV were inferior in sound quality to the same file stored on the AppleTV disk and played-back locally. The conclusion at the time was that WiFi and ALAC were compromising the SQ. These tests were all done through a Pace-Car 2 reclocker to reduce jitter, so the differences were not jitter, they are data differences.

Recently, he did another set of experiments after accidently playing a track with iTunes that had been ripped with EAC on a PC laptop.

He discovered that both the 44.1 EAC .wav rip and the ALAC track that was created from the EAC .wav rip (using iTunes) were superior in SQ to the same track ripped to ALAC directly using iTunes on the Mac.

He went back and did the WiFi experiment with the EAC ripped track converted to ALAC. This time, the track sounded identical whether played WiFi through the AppleTV or locally off the AppleTV disk.

This says that iTunes may have a problem with ripping tracks in general, or at least to ALAC.

I recommend those with Mac's that also have PC's try this and report back. If folks are ripping thousands of tracks using iTunes to ALAC and these tracks are somehow broken, they may have to do all of this over again.

Steve N.
Empirical Audio

 

[espressogeek]

Perhaps a packet capture could be used to figure this out.

 

[scompton]

I've been using DbPowerAmp to rip. It uses Nero to encode ALAC. It seems to be a little less of a resource hog than iTunes. Hopefully it's OK

 

[TheMarchingMule]

Oh bollocks, and I have my iPod here while my main computer is six hours away.

 

[krmathis]

Interesting! I never had full trust in iTunes as a CD ripper anyway.
So use Max for all my ripping needs. Apple Lossless as codec.

 

[Tryptonique]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif A Customer of mine has been doing a lot of experiments for me to determine the best-possible computer playback, both at 44.1 and upsampled to 24/96. His early testing with 44.1 tracks showed that ALAC files streamed WiFi to an AirPort Express or Apple-TV were inferior in sound quality to the same file stored on the AppleTV disk and played-back locally. The conclusion at the time was that WiFi and ALAC were compromising the SQ. These tests were all done through a Pace-Car 2 reclocker to reduce jitter, so the differences were not jitter, they are data differences. Recently, he did another set of experiments after accidently playing a track with iTunes that had been ripped with EAC on a PC laptop. He discovered that both the 44.1 EAC .wav rip and the ALAC track that was created from the EAC .wav rip (using iTunes) were superior in SQ to the same track ripped to ALAC directly using iTunes on the Mac. He went back and did the WiFi experiment with the EAC ripped track converted to ALAC. This time, the track sounded identical whether played WiFi through the AppleTV or locally off the AppleTV disk. This says that iTunes may have a problem with ripping tracks in general, or at least to ALAC. I recommend those with Mac's that also have PC's try this and report back. If folks are ripping thousands of tracks using iTunes to ALAC and these tracks are somehow broken, they may have to do all of this over again. Steve N. Empirical Audio

I'm interested in the actual data here. As we all know here, "sound quality" has a subjective quality to it. Is there any indication that any data was lost or that the EAC ripped and converted ALAC files were somehow fundamentally different than files ripped directly from iTunes in ALAC format?

I ripped all of my CDs to ALAC straight from my computer, so this obviously concerns me. However, I would obviously need more information actually demonstrating some sort of discernible lack of quality with those ALACS (and an explanation of what criteria were taken into account to determine that) if I'm going to go back and really re-rip all of my CDs (which I will definitely do if there is any hard empirical proof here).

Your screenname is audioengr...so I'm sure you understand where I'm coming from.

 

[blessingx]

Yeah, I'd like to see the proof on this one. Since iTunes introduction there has been lots of stories of issues (ALAC versus AIFF/WAV, sending through AirTunes, Redbook to ALAC versus Redbook to AIFF/WAV to ALAC, etc.) and every time there's a quantifiable test the results comes back clear.

I don't want to sound like an Apple apologist (for a few years I kept a PC around just for EAC), I appreciate the OPs 'may' in the title, we probably should be suspect of any ripper or encoder, but I think krmathis hit it on the head - some people just don't trust iTunes.

 

[nick_charles]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif A Customer of mine has been doing a lot of experiments for me to determine the best-possible computer playback, both at 44.1 and upsampled to 24/96. His early testing with 44.1 tracks showed that ALAC files streamed WiFi to an AirPort Express or Apple-TV were inferior in sound quality to the same file stored on the AppleTV disk and played-back locally. The conclusion at the time was that WiFi and ALAC were compromising the SQ. These tests were all done through a Pace-Car 2 reclocker to reduce jitter, so the differences were not jitter, they are data differences. Recently, he did another set of experiments after accidently playing a track with iTunes that had been ripped with EAC on a PC laptop. He discovered that both the 44.1 EAC .wav rip and the ALAC track that was created from the EAC .wav rip (using iTunes) were superior in SQ to the same track ripped to ALAC directly using iTunes on the Mac. He went back and did the WiFi experiment with the EAC ripped track converted to ALAC. This time, the track sounded identical whether played WiFi through the AppleTV or locally off the AppleTV disk. This says that iTunes may have a problem with ripping tracks in general, or at least to ALAC. I recommend those with Mac's that also have PC's try this and report back. If folks are ripping thousands of tracks using iTunes to ALAC and these tracks are somehow broken, they may have to do all of this over again. Steve N. Empirical Audio

It should be trivial to recreate the WAV file from the lossless file and run a bit-compare between a WAV ripped via EAC and the recreated WAV in FooBar this will show if the compressed file contains different raw data.

Better still if possible do a rip to WAV in EAC then get iTunes to convert to ALAC, then recreate the WAV from the ALAC and bit-compare.