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Airsculpture

macrumors 6502
Original poster
Oct 14, 2020
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I have my 2017 iMac plugged into my receiver via the display port USBC via a USBC to HDMI cable.

The midi setting only allows a specific at once setting in audio eg 24bit 96 so all output is sent at this level.

Is there any way of the iMac sending whatever the file is eg. 16bit 44 or 24bit 96 or 24bit 88, whatever the source file is without it either upsampling or downsampling, depending on your setting in the midi settings ?
 
I think you mean the Audio settings in the "Audio MIDI Setup" application. MIDI settings have nothing to do with audio settings.

I think the available settings are dependent on the device that is connected (and perhaps the cable itself…but I don't think so in this case).

Also, I think that software also plays a part in this. For instance, when I had a trial Tidal subscription I could set my PreSonus Audiobox USB 96 to 24bit/96kHz and listen at that setting but if I started Logic Pro X and a project in 24/44.1 my device settings would change on their own.

What receiver and software are you using?
 
I’m using iTunes and the HD mono price cable is connected to a HD capable Pioneer receiver
 
It looks, to me, like the receiver uses a "192 kHz/24-bit Wolfson Microelectronics Audio DAC" to do whatever that does.

The manual doesn't really explain what happens when you input, say, a 16/44.1 vs. a 24/96 file. I would think that anything lower than 24/192 probably isn't affected negatively until it is converted to analog and run through the analog circuit…which is the really important part.
 
My original question was regarding getting the iMac to send the native bit/freq of the file instead of sending everything according to the midi setting.

if the midi setting is 24/96, then all files irrespective of what the file is, is sent to the receiver as 24/96. Same if I set the midi as 16/44, everything is sent in that format.

What I was looking for, and without using something like bitperfect app, which in itself is unreliable and won’t work in combo with iTunes on Big Sur, I believe may well be impossible and I will have to settle for the iMac sampling everything to what the midi is set to. Otherwise it will mean changing the setting for every album that is different Which is clearly not practical.

The receiver is not the problem, the DAC auto decodes whatever it is given to analogue. The issue is the iMac sending digital at a set bit/freq and ignoring what the original files actually are, whether they are 16/44 or 24/96 or even some DSD files I have.
 
My original question was regarding getting the iMac to send the native bit/freq of the file instead of sending everything according to the midi setting.

if the midi setting is 24/96, then all files irrespective of what the file is, is sent to the receiver as 24/96. Same if I set the midi as 16/44, everything is sent in that format.

What I was looking for, and without using something like bitperfect app, which in itself is unreliable and won’t work in combo with iTunes on Big Sur, I believe may well be impossible and I will have to settle for the iMac sampling everything to what the midi is set to. Otherwise it will mean changing the setting for every album that is different Which is clearly not practical.

The receiver is not the problem, the DAC auto decodes whatever it is given to analogue. The issue is the iMac sending digital at a set bit/freq and ignoring what the original files actually are, whether they are 16/44 or 24/96 or even some DSD files I have.
...I don’t know very much about hdmi capabilities... but I think you have the answer at reach: if you’re using iMac’s internal DAC as output device, you’re tied to its settings. I suppose you should be able to add your receiver as output device in “midi audio“ app. Anyhow, if you get digital audio out of a mac, it must reach a DAC to be audible... and, then, it should be discoverable in midi-audio app (and configured).
After that, things depend on external devic/dac... (but mine plays at required bitrate automatically).
If external dac doesn’t show in “midi-sound”, that would mean that hdmi is giving analog audio to the receiver, so you rely on mac’s internal dac. If so, perhaps your receiver has another input (real digital).
 
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...I don’t know very much about hdmi capabilities... but I think you have the answer at reach: if you’re using iMac’s internal DAC as output device, you’re tied to its settings. I suppose you should be able to add your receiver as output device in “midi audio“ app. Anyhow, if you get digital audio out of a mac, it must reach a DAC to be audible... and, then, it should be discoverable in midi-audio app (and configured).
After that, things depend on external devic/dac... (but mine plays at required bitrate automatically).
If external dac doesn’t show in “midi-sound”, that would mean that hdmi is giving analog audio to the receiver, so you rely on mac’s internal dac. If so, perhaps your receiver has another input (real digital).

I have no problem receiving audio via the USBC to HDMI cable. What I have an issue with is the iMac not sending the sample/bit rate natively and the iMac sending them over in whatever is set in the midi settings, irrespective of what the actual file is

i.e. a 16/44 file is sent to the receiver as 24/96 if that is the setting in the midi control panel.

There is no auto setting in the midi control panel and so the output of the iMac is tied to whatever the output setting is in the midi control panel.
 
I have no problem receiving audio via the USBC to HDMI cable. What I have an issue with is the iMac not sending the sample/bit rate natively and the iMac sending them over in whatever is set in the midi settings, irrespective of what the actual file is

i.e. a 16/44 file is sent to the receiver as 24/96 if that is the setting in the midi control panel.

There is no auto setting in the midi control panel and so the output of the iMac is tied to whatever the output setting is in the midi control panel.
Macs don’t “send” sound files. You can send a sound file into an e-mail, yes, but you should be using a music-player app to play the file!
I use Audirvana as the player in my mac. I configured my external DAC (Dragonfly Red) at maximum possible bitrate in midi-sound utility. Audirvana takes control over configured settings, so the DAC automatically detects bitrate and plays in consequence (and light color in dac shows it is so). If I change output device to internal dac, behavior is the same. The player app in mac decides.
What is your “output device“ in midi-sound utility? What do you mean with “sending“ from the mac? An external player with dac just “gets” the file and adjusts itself automatically and plays the file (but that external device must be visible and set as default).
I still don’t understand what device really plays your files... and still don’t know what device is set as default output in your mac. Sorry.
 
Thanks for the reply J

I am playing music on the Mac in iTunes and and the audio is being passed to my Marantz receiver. The Marantz autodetects what bit rate and sample rate it is receiving and plays it accordingly. It will display the information of what it receives.

As you can see in the screenshot in this example, I am playing a 16/44 lossless file but the midi setting on the Mac is set to 24/96. The Marantz receives 24/96 and processes the audio accordingly. If I played the same file set in the midi setting on the Mac at 16/44, the receiver would display 16/44.

So the Mac is either upsampling, downsampling or playing the correct bit rate and sampling as determined in the Midi setting and not just playing whatever the bit rate / sampling rate of the file is.

What I wondered is how to get the Mac to process the bit rate/ sampling rate natively/automatically without the need to keep changing the Midi setting on the Mac.

Currently I have it set on 24/96 2 channel so that my 24/96 files are played correctly but that means any lower quality files, like the 16/44 lossless ALAC or AAC files are upsampled to 24/96 ( unless I manually change the Midi setting ).
 

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Thanks for the reply J

I am playing music on the Mac in iTunes and and the audio is being passed to my Marantz receiver. The Marantz autodetects what bit rate and sample rate it is receiving and plays it accordingly. It will display the information of what it receives.

As you can see in the screenshot in this example, I am playing a 16/44 lossless file but the midi setting on the Mac is set to 24/96. The Marantz receives 24/96 and processes the audio accordingly. If I played the same file set in the midi setting on the Mac at 16/44, the receiver would display 16/44.

So the Mac is either upsampling, downsampling or playing the correct bit rate and sampling as determined in the Midi setting and not just playing whatever the bit rate / sampling rate of the file is.

What I wondered is how to get the Mac to process the bit rate/ sampling rate natively/automatically without the need to keep changing the Midi setting on the Mac.

Currently I have it set on 24/96 2 channel so that my 24/96 files are played correctly but that means any lower quality files, like the 16/44 lossless ALAC or AAC files are upsampled to 24/96 ( unless I manually change the Midi setting ).
...I’m not near my mac now, but I‘ll fiddle with this iTunes thing. Well, I think iTunes is the culprit. I just use it for my Music subscription, because I don’t like how iTunes plays my own files. I have plenty hi-res files (different bitrates FLAC, DSD, MQA...) and I soon understood I needed a player able to send the proper signal to my ext. DAC.
AFAIK the system, macOS, is unable to “send” the bitperfect file without the help of a dedicated app. (You can try PinePlayer to experiment, as it’s free and in the AppStore).
I’m not an expert, but I realized time ago that “player apps” can override or interfere with general audio/midi app settings (midi here has nothing to do; the name of the utility app is misleading).
Another thing to note is that Finder is able to play FLACs natively (but just in “preview”! no double clicking), and bitrate is shown in info panel.
I was a big iTunes fan, but it has grown just for “Apple Music”, and lastly it was causing many problems with my own music collection. (And, while .aac is nice, alac is less convenient than flac, in my experience with these strange things in sound routing).
It seems your problem is known: https://www.pooraudiophile.com/2016/02/how-to-play-high-resolution-audio-with-apple-itunes.html
 
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Yeah I tried Pine Player. Similar results, whatever is set in audio options in the Audio Midi control panel governs the bitrate/sample rate is received and displayed on the receiver.

Starting to think it can't be done.

I used to use Bitperfect app which most of the time did the job but contrary to its name, it wasn't perfect and sometimes upsampled as well.

Now being on Big Sur but still using iTunes, Bitperfect won't work as it expects the Music app to be used.

On every version of MacOS it's been the same, the audio midi panel is the overrider and everything is output at whatever is set in there.

It makes no odds to sound quality, just unnecessary upsampling. Just my OCD hates it LOL
 
I completely understand your problem. It’s been a nightmare for me to reach a point where ever seems to work as it should with my audio files (and I’m even more exigent than you!).
I think it’s still unresolved problem: every player I‘ve tried has a special convenience and and some specific misses.
Audirvana is working nice for me. I’ve tried with an external FiiO dac and my actual Dragonfly dac; in both situations, I just set in midi utility maximum bitrate allowed by ext. dac, but it seems Audirvana manages this without problem, as -in both- the correct light corresponding file bitrate always worked. (But nothing is perfect! Audirvana makes strange things with MQA... LOL).
You’ll have to wait for a while... as this Big Sur thing makes things worse, by now. (I’m in Mojave).
A “double“ upsampling is not so bad 😉
 
Is there any computer OS that's capable of this?

I don't know what happens, macOS system software-wise, when a user changes the audio settings in Audio MIDI Setup but I would guess that something happens with Core Audio (perhaps a reset) when it's done. Such a hiccup may cause issues if it was happening on the fly.

What is the effect, to your ears, of audio being upsampled to 24/96?
 
None. I just wanted the files played as they exist, either 16/44 or 24/96 with no upsampling or downsampling.

I will have to leave it at 2 channel 24/96 to cover my hi-res files
 
By the way, my FiiO DAP does exactly the same thing on the fly with no issue with far less processing power than the iMac.

Anyway, who knows.
 
Now that Apple Music features lossless and high-res lossless at varying sampling rates, this “issue” affects many more users. macOS needs to allow the output bit depth and sampling rates to automatically match the content.
 
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