[foobar2015]

I posted this in Fiio forum. But I don't get any traction there. So I decided to post it here.
 
I did a test by downloading a sample multichannel PCM from http://www-mmsp.ece.mcgill.ca/documents/audioformats/wave/Samples/Microsoft/6_Channel_ID.wav . I encoded it as ALAC and FLAC. I tested them in PC with foobar2000. All channel sounds right to me.

However, when I play them back in Fiio X3II with firmware 1.4:

1. ALAC is a total disaster. I can hear all channels from my headphone but all channels are mislocated.

2. FLAC is a mess, too. It handle front left and front right correctly. But I don't hear rest of the channel. I beleive it didn't down mix multichannel.

3. PCM is acceptable but missing subwoofer channel.

I think this is a serious bug in Fiio X3II player when decode multichannel files. The specs claim it can play all sorts of lossless format. But it failed to meet this specs.

 

[ProtegeManiac]

The X3 uses a stereo - aka 2.0 - DAC, how is it a bug that it can't play 5.1? "All" in the specs description just means it will play all stereo files, it doesn't have a built-in DSP chip as on some receivers and soundcards to downmix on the fly (PCs can downmix using software and the processor).

 

[foobar2015]

The problem is the following:
 
1. In X3II specs, Fiio claims that it supports all lossless audio format. In US, false statement in advertising is illegal.  
2. If X3II doesn't plan to support multichannel, it should not play the files at all or output error message. But it does play PCM, ALAC, FLAC in a unacceptable way.
 
X3II uses Cirrus CS4398 chip as DAC. I skim through its data sheet --http://pdf.datasheetcatalog.com/datasheet2/0/0060lzqyyy2hzo2od8s047thdeyy.pdf . It takes PCM and DSD as input. I understood that it doesn't support native decode multichannel DSD. However, for ALAC, PCM or FLAC, it should be software decoded to PCM by Fiio DAP CPU written in form of firmware.

 

[ProtegeManiac]

Quote:

Originally Posted by foobar2015 /img/forum/go_quote.gif

 

1. In X3II specs, Fiio claims that it supports all lossless audio format. In US, false statement in advertising is illegal.  

 

The problem here is in interpretation. They're thinking all stereo, since that's how music is normally recorded, and how multichannel audio never really took off with speakers where you can barely find anything that isn't HT-related (apart from some SACDPs) that has more than two channels for analogue output or amplification, much less with headphones where space is even more of a premium on top of isolation (which is why it's more common to see $1,000+ headphones with huge drivers). I won't be surprised if they gave no thought at all to down-mixing either since their presumption would have not even included multichannel given it didn't get that popular. At the same time, there's really not much of a point unless it's done properly from recording to playback system: that means you record the multichannel track to play back through all five speakers in front. This is one of the reasons why this idn't really get popular apart from those with HT systems, in which case, they're more likely to buy the video of a live performance.

 

You can always just go ahead and just file a case with the regulatory body that oversees this, whether it's the Trade Dept or the communications devices regulators. Best case scenario, they get their firmware developers to work on including a downmixing program; worst case, we get to have Fiio be very, very, very clear with how they say anything, like coffee cups that say "Caution: Contents VERY Hot" because too many people assumed fast food means you can swig it right from the counter without their noses sniffing how hot the steam is.

 

Quote:

Originally Posted by foobar2015 /img/forum/go_quote.gif

2. If X3II doesn't plan to support multichannel, it should not play the files at all or output error message. But it does play PCM, ALAC, FLAC in a unacceptable way.

 

X3II uses Cirrus CS4398 chip as DAC. I skim through its data sheet --http://pdf.datasheetcatalog.com/datasheet2/0/0060lzqyyy2hzo2od8s047thdeyy.pdf . It takes PCM and DSD as input. I understood that it doesn't support native decode multichannel DSD. However, for ALAC, PCM or FLAC, it should be software decoded to PCM by Fiio DAP CPU written in form of firmware.

 

It's not but it's possible that the software instead of getting a full-on error assumes that some channels are L and R, instead of getting totally flabbergasted that there are five of them, and basically just uses two and discards the rest. It wasn't originally a part of the plan but since it's doable by software filing a case will get them moving faster in order to get that done, or US sales via official dealers will stop.

 

[foobar2015]

When Fiio decode multi-channel ALAC and FLAC, I can hear other channels besides front left and front right. But they are all dislocated. I still insist it is a software bug in their firmware. Because they are software decoded.  
 
Down mix PCM algorithm may require some matrix multiplication plus some normalization. I don't know how to down mix multichannel into stereo unless I dig deeper.

 

[ProtegeManiac]

Quote:

Originally Posted by foobar2015 /img/forum/go_quote.gif

When Fiio decode multi-channel ALAC and FLAC, I can hear other channels besides front left and front right. But they are all dislocated. I still insist it is a software bug in their firmware. Because they are software decoded.  

 

Down mix PCM algorithm may require some matrix multiplication plus some normalization. I don't know how to down mix multichannel into stereo unless I dig deeper.

 

What I was saying is that this wasn't in their original design for it, that they meant "all stereo" when they said all, and not to take "hear other channels...dislocated" to mean that they meant "all including surround recordings" just because you didn't get an error instead of "all channels...dislocated." I haven't been following the thread closely but no one before you tried multichannel recordings since everybody assumed that "all" meant "all formats, lossless and compressed, in stereo."

 

In any case as you claim it's illegal for them to use "all," so there being just one person should be enough to progress through regulatory cases to have them change the wording or move quickly to incorporate a proper downmix in their firmware, in the same sense that it only takes one person to put a cup next to their crotch for McDonald's to change what's written on their cups. If it's illegal then it will progress through regulatory channels - I mean it's not like Fiio will hire some gun lobby law firm to fight you on that. Send the regulatory bodies an email and get them moving on it, ask what else needs do you need to do, etc.