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RE: What Bit-Rate does an IMac put out on USB?

88.97.21.18

PAR

In Reply to: RE: What Bit-Rate does an IMac put out on USB? posted by oldmkvi on September 16, 2017 at 08:46:31

If I understand your question correctly you are basically asking how you identify the bit depth and sample rate that your Audioquest Dragonfly is receiving. I hope I am right.
Internet radio is normally 16/44.1 or 16/48 for this purpose. Even if it is a lossy service e.g MP3 or AAC etc, to the DAC's display it is still 16/44.1 or 16/48. I have never come across a 24 bit internet radio station although streaming services ( usually the paid for variety) can be at this bit depth. Other inmates may have further advice.
The Dragonfly logo on the DAC changes colour according to the sample rate it receives. It cannot be set to a different rate, it selects automatically.
This should not be confused with the data streaming rate of the programme material given a lossy (MP3 etc.)service which is processed by the media player to be passed to the DAC. Even if the stream is only a low rate service the format that the DAC will show is 16:44.1/48. If the sample rate is 44.1KS/s the logo will light as green, 48 blue, 88.2 amber and 96 magenta. with MQA files and the latest Dragonfly software the logo lights up in a purple shade. I am led to believe the latter having no access to MQA myself.
If you have bought a new Dragonfly it comes with a "flight manual" that documents all of the logo colour information although I guess you should also find it on the Audioquest website.
NB: if the logo is red this means that the DAC is on standby.

Edits: 09/16/17 09/16/17

Follow Ups:

The thing is that the Dragonfly Red Does change color - oldmkvi 14:14:56 09/16/17 (5)
to whatever I set it to in Midi Audio Prefs.
Green for 44.1, Blue for 48, and Magenta for 96.
The Flight Manual just said to set it for whatever is being sent to it. ( or so I remember).
Which is the problem, as I don't know.
It doesn't make much or any real difference that I can hear, but I'd like to know what it really"IS", so to speak.
- RE: The thing is that the Dragonfly Red Does change color - PAR 15:29:38 09/16/17 (1)
  I am sorry but I understood your reference to "setting" to refer to the Dragonfly's sample rate which cannot be changed as it is selected automatically.
  
  I now understand you meant the setting in Audio Prefs. I attach a link to the flight manual where they suggest 44.1 is most common. I have the same problem myself with Windows where the audio settings cover both bit depth and sample rate. Whatever is selected means that the incoming data is either upsampled or downsampled unless one has fortuitously hit upon a mirror of each other.
  
  As I am not a Mac user I don't know if a similar thing occurs but I guess so.
  
  This does get complicated. From a Windows point of view in earlier versions of Windows you could hover the cursor over the browser window playing the station and see its properties. But this would be the incomimg programme data rate which for lossy stations is what the codec is using e.g 192Kb/s.
  
  I don't think that there is a way of finding out what the internet station's player is sending to the DAC via Mac audio preferences except by what the DAC tells you ( which will presumably be what rate is set in audio preferences !).
  
  The solution would be to avoid Mac MIDI audio preferences or Win Audio. In Windows this can be done by using a WASAPI session whereby the incoming data is passed through bit perfect. The downside is that I haven't come across any web based (in browser) player that caters for this. I also have never heard of a similar Mac facility so maybe the MIDI audio preference can be bypassed some other way? I haven't seen inmates complaining about Mac up/downsampling when not required.
  
  I think that you may have to accept that internet radio is normally configured to be easily usable by everyone and that what we may think of as useful or essential information is just not catered for. I would just set the audio preference to 44.1 as this is likely to cover most of this type of input. If you change it to 48.0 I would be amazed if you can hear a difference anyway.
  
  If you subscribe to a lossless streaming service and use a desktop player then you may be able to see the rate sent ( e.g. Qobuz for us Europeans) or, if the rate is fixed , know what it is from the supplier's promo or instructional material ( e.g. Primephonic).
  
  Sorry but in the end I haven't been much help I am afraid.
  - http://www.audioquest.com/pdfs/dragonfly/DragonFly-FlightMan (Open in New Window)
  - RE: The thing is that the Dragonfly Red Does change color - oldmkvi 07:27:53 09/17/17 (0)
    amazed if you can hear a difference anyway.
    
    Well, that's right!
    
    I think I stirred things up too much with this thread, but I appreciate all the replies.
- So, in your OP, you actually wanted sample rates, not bit rate? - Chris from Lafayette 15:08:39 09/16/17 (2)
  If you want sample rates, that would be variable, depending on the type of file being sent, right?
  - Yes, sample rate. - oldmkvi 07:33:31 09/17/17 (1)
    I'm just trying to match what's being played, often Joe Frank, to the Dac.
    I was hoping there was a way to tell.
    The different choices don't really sound different.
    But the Dacs I use all read out whatever I select in Midi Audio, there's no Automatic Detection.
    Not with HQ or JRiver or AV+ of course, just Internet Radio.
    The stations I listen to aren't on ITunes either.
    Anyway, thanks for your input!
    - RE: Yes, sample rate. - Charles Hansen 12:21:41 09/17/17 (0)
      > > But the Dacs I use all read out whatever I select in Midi Audio, there's no Automatic Detection. < <
      
      This is true of every DAC in the world. The DAC can only report the received sample rate. Unless using some of the programs and settings described elsewhere in the thread, the OS will use its built-in low quality SRC conversion program to make all audio the same rate so it can mix it. Unless you know ahead of time the correct sample rate and manually set it, or use special software with (with special settings in Windows), there is no way to affect how the OS changes the sample rate - certainly not by any DAC.
      
      Hope this helps.

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