[Nick24JJ]

Thank you, all, so very much! Now it starts to become clearer, all what's happening to that poor audio signal over Bluetooth...

Can someone please explain what is the purpose of those Bluetooth sample rates and bit rates, on my Android 12 phone, Developer settings?
I have the option to set the sample rate to 44.1, 48, 88.2 and 96 kHz. I can also set the Bluetooth bits per sample to 16, 24, 32 bits/sample. Besides that, both of these settings have a preferred/default option.

What do these do? By setting the Bluetooth sample rate to 44.1 kHz, are you forcing Android audio to that? Same for the bits/sample? This is what I understand, that you can force it, otherwise why do they have it there?

If I will connect the DAC with a cable to my phone, I do not have these options.

 

[monsieurfromag3]

Totally agree except for the 48 kHz limitation, which is true for some devices (especially older ones) but not all, not anymore. Recent versions of android have support for 24/192 built-in, if the hardware is there.

Reference:

https://source.android.com/devices/audio/highres-effects

Good to know! But it’s always a multiple of 48 right?

 

[monsieurfromag3]

Thank you, all, so very much! Now it starts to become clearer, all what's happening to that poor audio signal over Bluetooth...

Can someone please explain what is the purpose of those Bluetooth sample rates and bit rates, on my Android 12 phone, Developer settings?
I have the option to set the sample rate to 44.1, 48, 88.2 and 96 kHz. I can also set the Bluetooth bits per sample to 16, 24, 32 bits/sample. Besides that, both of these settings have a preferred/default option.

What do these do? By setting the Bluetooth sample rate to 44.1 kHz, are you forcing Android audio to that? Same for the bits/sample? This is what I understand, that you can force it, otherwise why do they have it there?

If I will connect the DAC with a cable to my phone, I do not have these options.

Someone explained convincingly that it’s better to keep the bit rate at 32, for a reason I can’t remember
As to sample rate, sadly it won’t force Android to resample to that setting - that would be the dream, alas it’s locked, which is why these options disappear when a USB DAC is plugged. It only controls the sample rate for the BT stream itself, which is useful only when you can predict it for whatever is playing.

 

[Nick24JJ]

Someone explained convincingly that it’s better to keep the bit rate at 32, for a reason I can’t remember
As to sample rate, sadly it won’t force Android to resample to that setting - that would be the dream, alas it’s locked, which is why these options disappear when a USB DAC is plugged. It only controls the sample rate for the BT stream itself, which is useful only when you can predict it for whatever is playing.

What do you mean with this? Explain, please!

Say, I'm playing a song in the Qobuz app. Or, even in the Amazon app. The song is 44.1 kHz. If I will lock the Bluetooth sample rate to 44.1 and in the Qudelix app disable all other sample rates besides 44.1, why won't the song play at 44.1? With all those options there, in the Developer settings, in the Qudelix app, it should. Otherwise, it does not make sense. Why are these settings there, then? What is their purpose?

 

[monsieurfromag3]

What do you mean with this? Explain, please!

Say, I'm playing a song in the Qobuz app. Or, even in the Amazon app. The song is 44.1 kHz. If I will lock the Bluetooth sample rate to 44.1 and in the Qudelix app disable all other sample rates besides 44.1, why won't the song play at 44.1? With all those options there, in the Developer settings, in the Qudelix app, it should. Otherwise, it does not make sense. Why are these settings there, then? What is their purpose?

You’re right, it should! And I think it shall. By predicting the sample rate for whatever is playing, I didn’t mean predict the Bluetooth sample rate, I meant predict the actual sample rate of the file itself. Like if it’s Tidal Hi-Fi, no MQA, you can be sure the file will be 44.1, so you can lock that in. If it’s variable I guess it’s better not to bother and, to quote myself, eat whatever resampling occurs!

If you lock the BT sample rate on your phone, and go as far as disabling any other sample rate in the Qudelix app, you are making double sure that’s the sample rate you’re getting. I don’t think the Qudelix will resample on its own anyway, so if you’ve disabled any sample rate beside 44.1, I don’t think it will even play a stream it receives in another sample rate.

 

[CactusPete23]

You’re right, it should! And I think it shall. By predicting the sample rate for whatever is playing, I didn’t mean predict the Bluetooth sample rate, I meant predict the actual sample rate of the file itself. Like if it’s Tidal Hi-Fi, no MQA, you can be sure the file will be 44.1, so you can lock that in. If it’s variable I guess it’s better not to bother and, to quote myself, eat whatever resampling occurs!

If you lock the BT sample rate on your phone, and go as far as disabling any other sample rate in the Qudelix app, you are making double sure that’s the sample rate you’re getting. I don’t think the Qudelix will resample on its own anyway, so if you’ve disabled any sample rate beside 44.1, I don’t think it will even play a stream it receives in another sample rate.

Any chance that you guys can take this bluetooth discussion to PM (Private Messages) ? A lot of your discussion is related to your specific phone and general bluetooth. And it looks like the same question and answers keep repeating. Thanks!

 

[rlw6534]

Good to know! But it’s always a multiple of 48 right?

It depends on the hardware/DAC but the Android OS itself now supports 44.1/48/88.2/96/176.4 and 192 kHz. My Huawei M5 only supports multiples of 48 though so it can vary.

 

[Safeinthemountains]

Thank you, all, so very much! Now it starts to become clearer, all what's happening to that poor audio signal over Bluetooth...

Can someone please explain what is the purpose of those Bluetooth sample rates and bit rates, on my Android 12 phone, Developer settings?
I have the option to set the sample rate to 44.1, 48, 88.2 and 96 kHz. I can also set the Bluetooth bits per sample to 16, 24, 32 bits/sample. Besides that, both of these settings have a preferred/default option.

What do these do? By setting the Bluetooth sample rate to 44.1 kHz, are you forcing Android audio to that? Same for the bits/sample? This is what I understand, that you can force it, otherwise why do they have it there?

If I will connect the DAC with a cable to my phone, I do not have these options.

Hi, I understand that you want to know what's happening under the hood... in this particular case (playing back from Amazon App, through Android OS, then through a BT Codec) I'm afraid it will be almost impossible to know, you can just guess...

It is true that resampling 44.1 to any 48Khz multiple could degrade the initial signal, and also passing trough a lossy codec (in this case LDAC) will always degrade the initial signal.
After all, I know you would like to obtain the best possible quality out of your device, but in this case I would simply ask myself; does the reproduction of the music sounds good to my ears ? Does it REALLY need to get any better ?
It is true that sometimes, when you switch from one device/system to another, you realize what you were missing later on. But apart from the technical considerations, is it really worth all this questionning ?

30 years ago there was really a compromise to be made between quality/convenience/recording media, and there were obvious differences between a high end HiFi system, and a portable player. Nowadays, at a certain price point (few 100's €/$) the quality is already great, and the differences become marginal.
Of course when you use wireless transmission there is a tradeoff with the codecs; technically you lose a bit of integrity of the original signal.
In the end, if your source file/stream is 16/44 and you play it trough LDAC 16/48 or anything above, because of the max bitrate of 990, there will be losses, but can you really hear it ?

Also the thing that seems a bit "stupid" to me is using a high sampling resolution/frequency (i.e 24/96) and then compress it in order to achieve a bitrate of 990Khz that is below the 1411Kb/s native bitrate of a 16/44 file; is it really worth it ? I guess the goal is to optimize the use of the bandwith in order to put more weight on the most relevant frequencies...

In the end I'm almost sure that what Qdelix app is displaying is the resolution/frequency of the Codec, nothing more. It is totally independant from the source file. Maybe the main point is how the stream is processed by your OS in between the app and the BT output.

On various Android devices I have used, sometimes the dev options let me freely choose the codec/bitrate/bit depht/frequency, but my ES100 was either stuck with Aptx-HD at 24/44 or LDAC adaptative depending on the particular device, and it seems to be the same for the Qdelix.
Personally, on a daily basis, even Std Aptx is OK for me for casual listening. When at home I use wired headphones on a proper DAP, which is a completely different experience

 

[monsieurfromag3]

Any chance that you guys can take this bluetooth discussion to PM (Private Messages) ? A lot of your discussion is related to your specific phone and general bluetooth. And it looks like the same question and answers keep repeating. Thanks!

No way my friend! This is the thread for a Bluetooth receiver and USB DAC, the interplay between source file and codec is one of the most legitimate concerns there are. Sorry if you feel inconvenienced, if you think we’re not making progress maybe you can shed some light, otherwise just press Ignore and you’ll be spared all of my messages. I’m trying to offer some insight into these convoluted processes that it’s taken me some time to consolidate in my head, and I wish someone had helped me clarify things earlier.

Hi, I understand that you want to know what's happening under the hood... in this particular case (playing back from Amazon App, through Android OS, then through a BT Codec) I'm afraid it will be almost impossible to know, you can just guess...

It is true that resampling 44.1 to any 48Khz multiple could degrade the initial signal, and also passing trough a lossy codec (in this case LDAC) will always degrade the initial signal.
After all, I know you would like to obtain the best possible quality out of your device, but in this case I would simply ask myself; does the reproduction of the music sounds good to my ears ? Does it REALLY need to get any better ?
It is true that sometimes, when you switch from one device/system to another, you realize what you were missing later on. But apart from the technical considerations, is it really worth all this questionning ?

30 years ago there was really a compromise to be made between quality/convenience/recording media, and there were obvious differences between a high end HiFi system, and a portable player. Nowadays, at a certain price point (few 100's €/$) the quality is already great, and the differences become marginal.
Of course when you use wireless transmission there is a tradeoff with the codecs; technically you lose a bit of integrity of the original signal.
In the end, if your source file/stream is 16/44 and you play it trough LDAC 16/48 or anything above, because of the max bitrate of 990, there will be losses, but can you really hear it ?

Also the thing that seems a bit "stupid" to me is using a high sampling resolution/frequency (i.e 24/96) and then compress it in order to achieve a bitrate of 990Khz that is below the 1411Kb/s native bitrate of a 16/44 file; is it really worth it ? I guess the goal is to optimize the use of the bandwith in order to put more weight on the most relevant frequencies...

In the end I'm almost sure that what Qdelix app is displaying is the resolution/frequency of the Codec, nothing more. It is totally independant from the source file. Maybe the main point is how the stream is processed by your OS in between the app and the BT output.

On various Android devices I have used, sometimes the dev options let me freely choose the codec/bitrate/bit depht/frequency, but my ES100 was either stuck with Aptx-HD at 24/44 or LDAC adaptative depending on the particular device, and it seems to be the same for the Qdelix.
Personally, on a daily basis, even Std Aptx is OK for me for casual listening. When at home I use wired headphones on a proper DAP, which is a completely different experience

I agree it’s largely guesswork as to what processes the streaming companies are using behind the scenes to construct their libraries. What files do they have access to for starters, and what do they do to those files?

On my part I see a clear difference between processes that are properly designed for audio by audio professionals, and generic software. In this sense the losses I experience using well-coded Bluetooth codecs, or heavily iterated and improved mp3 compression, bother me little. And mostly on an intellectual level. At the end of the day a great DAC/amp will give you 99.9% of your music and engagement from 320kbps mp3 transmitted via vanilla aptX. A crappy source will botch even the most pristine local DSD playback…
But Android is documented to employ the quickest and dirtiest algorithm it can find to resample music and not tax the CPU for the benefit of a couple of fussy audiophiles. Those guys are really taking a hatchet to your music and my ears can definitely tell the difference.

 

[skumrat]

When I enable 'oratory1990' autoEQ preset for my earphones, what target is it EQing them to? Harman In-ear target? It doesn't seem to specify. Also, how come I lose a fair bit of loudness when applying EQ?

 

[Safeinthemountains]

But Android is documented to employ the quickest and dirtiest algorithm it can find to resample music and not tax the CPU for the benefit of a couple of fussy audiophiles. Those guys are really taking a hatchet to your music and my ears can definitely tell the difference.

Yes, I've read it here and there, and I think that's the main issue ! Android original audio algorithm is not optimized for SQ. So even if you put one of the best USB DACs available, it is highly probable that you'll end up with degraded SQ...
Then, why do most of the manufacturers choose Android OS for their DAPs ? Maybe because there is no other "standard" linux-based open-source offering ? Also the mainstream apps run either on Apple devices or Android... Or maybe (I hope) they all have a way to bypass Android's stock software for outputting sound ? (i.e Hiby's Direct Transport Architecture)
Android is also well known in the world of musical computing, for being the OS that has lots of latency, this is why everyone uses IPads or iPhones for music recording, vitual instruments and live performance

 

[rlw6534]

When I enable 'oratory1990' autoEQ preset for my earphones, what target is it EQing them to? Harman In-ear target? It doesn't seem to specify. Also, how come I lose a fair bit of loudness when applying EQ?

Yes, the AutoEQ presets are for Harman in-ear or over-ear depending on what type of headphone. The gain is reduced to prevent clipping on the frequencies that are boosted by the EQ curve. You absolutely need that to be done for best quality.

 

[monsieurfromag3]

Yes, I've read it here and there, and I think that's the main issue ! Android original audio algorithm is not optimized for SQ. So even if you put one of the best USB DACs available, it is highly probable that you'll end up with degraded SQ...
Then, why do most of the manufacturers choose Android OS for their DAPs ? Maybe because there is no other "standard" linux-based open-source offering ? Also the mainstream apps run either on Apple devices or Android... Or maybe (I hope) they all have a way to bypass Android's stock software for outputting sound ? (i.e Hiby's Direct Transport Architecture)
Android is also well known in the world of musical computing, for being the OS that has lots of latency, this is why everyone uses IPads or iPhones for music recording, vitual instruments and live performance

All of the major Android DAP manufacturers have a variation on resample bypass - all except Sony, which puts them off the list as far as I’m concerned. Which is sad as I’d rather go for them than the Chinese guys, but it is what it is. I just hope Cowon release a proper Android DAP at some point - or Qudelix!

 

[Nick24JJ]

... This is the thread for a Bluetooth receiver and USB DAC, the interplay between source file and codec is one of the most legitimate concerns there are. ...
,,, I’m trying to offer some insight into these convoluted processes that it’s taken me some time to consolidate in my head, and I wish someone had helped me clarify things earlier.

Hello again,

Here is the response I've got from Qudelix customer support. My question was:

- If I will select 44.1 kHz in my phone's Developer settings and also set 44.1 kHz in the Qudelix App, is there any resampling happening?

They replied:


Hi,

Sink devices (Receivers) send the supported sample rate information to the Source devices (smartphones) at the beginning, when making Bluetooth A2DP connection.
A source device (smartphone OS) selects one of them when playing audio to a connected sink device.

USB DACs also work in a very similar way.
USB DAC sends the supported sample rate information to a PC when making the connection.
You can select a sample rate to use in the Windows Sound control panel.

But sometimes, it's not possible or it is tricky to select the sample rate at the source device.

Qudelix-5K allows you to fix the same rate. (it's a unique feature, 5K exclusive.)

For example, if you want to use 44.1KHz only, just check 44.1 and uncheck the other options in the Qudelix app.
Then, 5K would let the source device know that the 5K supports 44.1, exclusively.
Eventually, the source device would always stream audio at 44.1kHz.

Most music tracks are 44.1 KHz
If you want to stream music with no SRC (sample rate converter), then you just check the 5K supported FS 44.1 only.
Then, the source always stream audio at 44.1 automatically.
Streaming audio at 44.1KHz is also good for LDAC performance.
Compressing 44.1 audio at 909kbps would perform slightly better than compressing 96kHz audio at 990 kbps.
Furthermore, 5K DAC running at 44.1 would give you longer battery time than 96khz.

Thank you~!

Source
PS: Minor editing for clarity

 

[superuser1]

Hello again,

Here is the response I've got from Qudelix customer support. My question was:

- If I will select 44.1 kHz in my phone's Developer settings and also set 44.1 kHz in the Qudelix App, is there any resampling happening?

They replied:


Hi,

Sink devices (Receivers) send the supported sample rate information to the Source devices (smartphones) at the beginning, when making Bluetooth A2DP connection.
A source device (smartphone OS) selects one of them when playing audio to a connected sink device.

USB DACs also work in a very similar way.
USB DAC sends the supported sample rate information to a PC when making the connection.
You can select a sample rate to use in the Windows Sound control panel.

But sometimes, it's not possible or it is tricky to select the sample rate at the source device.

Qudelix-5K allows you to fix the same rate. (it's a unique feature, 5K exclusive.)

For example, if you want to use 44.1KHz only, just check 44.1 and uncheck the other options in the Qudelix app.
Then, 5K would let the source device know that the 5K supports 44.1, exclusively.
Eventually, the source device would always stream audio at 44.1kHz.

Most music tracks are 44.1 KHz
If you want to stream music with no SRC (sample rate converter), then you just check the 5K supported FS 44.1 only.
Then, the source always stream audio at 44.1 automatically.
Streaming audio at 44.1KHz is also good for LDAC performance.
Compressing 44.1 audio at 909kbps would perform slightly better than compressing 96kHz audio at 990 kbps.
Furthermore, 5K DAC running at 44.1 would give you longer battery time than 96khz.

Thank you~!

Source
PS: Minor editing for clarity

This should be pinned to the first page, relevant info for some people who would want more clarity.