Questions about Bluetooth streaming

[craiglindley]

I am investigating the idea of streaming Internet radio to a bluetooth speaker. I understand that the esp32 cannot do both WiFi and Bluetooth at the same time so I was thinking of using 2 esp32's and connecting them together using i2s. Which brings me to my question. Does the Bluetooth streamer only run at 44100, 16 bit? I am asking because various Internet radio stations stream at 320kbps or 128k bps so I am not sure how to couple the url streamer on one esp32 to the Bluetooth streamer (a2dp) on another esp32. Any help would be appreciated.

Nice library BTW.

[pschatzmann]

Interesting question. One small disclaimer: I did't try this myself so I don't know all the stumbling blocks!
I think most likely you will be streaming mp3. So the relevant information is provided by the codec. I noticed that most often I am getting the following output:

• sample_rate: 44100
• bits_per_sample: 16
• channels: 2
  And this is exactly what you need for A2DP as well!

I suggest that you experiment first a little bit with the following sketch:
https://github.com/pschatzmann/arduino-audio-tools/tree/main/examples/examples-player/player-url-i2s

So there is a good chance that in most cases it might just work...

[pschatzmann]

What I forgot to mention: As far as I know A2DP supports some adaptive speed adjustments and can automatically switch between the following rates

• 16000
• 32000
• 44100
• 48000

[craiglindley]

Excellent thanks for the quick response. will try some things and report back.

…

On Wed, Oct 27, 2021 at 11:39 AM Phil Schatzmann ***@***.***> wrote: What I forgot to mention: As far as I know A2DP supports some adapting speed adjustments and can automatically switch between the following rates - 16000 - 32000 - 44100 - 48000 — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#26 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AH6K5D2I4G5IW2GFR7NJWQ3UJBBN7ANCNFSM5G23DGDQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

-- Craig Lindley / Heather Hubbard New Recordings are here <http://craigandheather.net/spellbound.html> Personal Website is here <http://craigandheather.net> Please call the Rockrimmon house. Our cell phones don't work at home. Rockrimmon House: (719) 426-9873 Craig's Cell: (719) 502-7925 Heather's Cell: (719) 571-0944 If you’re one in a million, there are now more than seven thousand people exactly like you.

[craiglindley]

So now I have a question about the streams-i2s-a2dp.ino sketch. I got it to compile successfully and to download into my esp32. I assume that it should connect to my BT amplifier using the name of MyMusic but it does not. It stalls at the a2dpStream.begin(TX_MODE, "MyMusic"); function and does nothing else. Any ideas of what I am doing wrong?

[craiglindley]

Never mind I got it to work

[pschatzmann]

What was the problem?

[craiglindley]

My stupidity. I left out a letter in the bluetooth name. But now I have a different problem which I am researching. I connected up two esp32s using i2s as follows: ESP32 #1 ESP32 #2 Vin Vin Gnd Gnd 22 SD 32 21 WS 15 5 SCK 14 Where ESP32 #2 is the device which transmits the Bluetooth audio. I first ran your sketch streams-generator-a2dp.ino on esp32 #2 and got a nice tone from my speaker. I then replaced that sketch with streams-i2s-a2dp.ino and put streams-generator-i2s.ino on esp32 #1 after changing the pin numbers of course and got nothing but random garbage out. Since I wired Vin/Gnd in both devices together they boot at the same time and I wonder if this is part of the problem. I'll let you know what I find out.

…

On Thu, Oct 28, 2021 at 10:53 PM Phil Schatzmann ***@***.***> wrote: What was the problem? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#26 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AH6K5D3ILQMM26MFITAQ4TTUJIZGXANCNFSM5G23DGDQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

-- Craig Lindley / Heather Hubbard New Recordings are here <http://craigandheather.net/spellbound.html> Personal Website is here <http://craigandheather.net> Please call the Rockrimmon house. Our cell phones don't work at home. Rockrimmon House: (719) 426-9873 Craig's Cell: (719) 502-7925 Heather's Cell: (719) 571-0944 If you’re one in a million, there are now more than seven thousand people exactly like you.

[craiglindley]

Excellent suggestion which I did. The resultant serial plotter image is attached:

As you can see the sine wave is getting through but it is being cut off periodically and that is the reason for the noise I am hearing through my BT speaker.

I then changed the channel count to 1 and the sine wave comes through clearly although I do hear some crackles which might be due to only a single channel being fed to the BT speaker.

Any ideas on why the stream is being interrupted?

[craiglindley]

I now know why. The AudioLogger. If I comment out the following line in the code for esp32#1

// AudioLogger::instance().begin(Serial, AudioLogger::Info);

the major dropouts go away completely. There is still however, crackling in the BT output but that might be discontinuities in the sine wave generation. I'll next run audio from spiffs to see if it is impacted

[pschatzmann]

Good point - I was usually using lower sample rates...
You could alternatively use

• AudioLogger::instance().begin(Serial, AudioLogger::Error);
• AudioLogger::instance().begin(Serial, AudioLogger::Warning);
  to request another log level. The default is Warning

[pschatzmann]

Today I was trying to do some improvements to the A2DPStream class in relation to the AudioPlayer and finally have the MP3 Decoding from a SD Drive with output to A2DP working with a perfect quality.

Maybe this also helps with your quality issues.

[monojk]

I now know why. The AudioLogger. If I comment out the following line in the code for esp32#1

// AudioLogger::instance().begin(Serial, AudioLogger::Info);

the major dropouts go away completely. There is still however, crackling in the BT output but that might be discontinuities in the sine wave generation. I'll next run audio from spiffs to see if it is impacted

Did you manage to get a good quality. I am currently struggling with distortions: #149

[podaen]

If you have the posibility to add a button to switch between a2dp and internet radio... that would be the most easiest way there is.

[pschatzmann]

Since the releasing of the memory (and restarting of A2DP) is not working reliably I would store the requested scenario in the NVS and reboot. In the setup, the start up logic would consult the NVS to select either to start up the A2DP or the WIFI.

[BlackBirdDevelopments]

I would like to join this discussion, but with a different question.
@pschatzmann as you already know, I got a stream from i2s to a2dp. Everything works fine and I have no issues.
In addition, I would like to visualize the sound I hear or the sound from the mic. As far as I know, the microphone gives me digital data and the data sent to the BT speaker are as well digital. Is there a point in the code where I can cut in and either print the data as analog to a file (while connected to the PC) or assign it to a pin, where I can visualize it than with an oscilloscope?

Another thing, It might be nice to have the option of connecting to my earbuds (that already works perfectly) or to connect to my phone and then use recording software to either visualize or just for showing purpose. Issues could be, that the phone should be the Master in this case and to change the BT identifier of the ESP, in a manner that everything works together.

[pschatzmann]

If I understand you want to have access to the processed audio data. I can give you 4 different approaches:

1. Currently you use my copy helper class, but you could just replace it with a readBytes to get the data and do a write(data, len) to the A2DPStream and your additional processing.
2. I have a callback method (setCallbackOnWrite) in the StreamCopy class which you could use. It would call the callback that you have provided and provides the actually processed audio data. I am currently using this mechanism to extract e.g. the metadata.
3. You could create your own special purpose output class (see MetaDataPrint) and in your sketch wrap it with the A2DPStream in a MultiOutput class which will be the copy target. This way you end up with a reusable visualization class that gets the data along with the A2DPStream.
4. You could create a subclass of the A2DPStream class and overwrite the write (const uint8_t *data, size_t len) method. You would add you own logic and also call A2DPStream::write(data,len) from there. This way you get a reusable A2DP visualization class.

Just pick the one that makes most sense for your project...