I2S to Bluetooth bridge

[Prog32aw]

First of all, many thanks for this great project, Phil!!

I built a webradio on ESP32 basis and it works fine outputting I2S data to a PCM5102. Using the same signals to another ESP32 which works as a I2S to Bluetooth bridge works as well, using your A2DPBluetooth source. But: the sound is perfect, but this depends on the bitrate of the radio station. All bitrates above 128000 work perfect, 128000 works, but with regularly tic-sounds, maybe 8 times a second.
The I2S to Bleuttooth bridge works in RX mode, so the sender controls all three lines I guess. I played with the sample_rate with strange results. In my opinion the sample_rate and data rate should be controlled by the master controller clk. This seems not to be true. May somebody has an idea to solve this problem?

Thanks

[pschatzmann]

I don't quite understand what your problem is ?
Is it a I2S connection between 2 ESP32 ?

[Prog32aw]

The problem is, that the sound is disturbed by frequent, regularly tic-sounds. This happenes with radio stations <=128000 bit/s (MP3).
Yes, it is an I2S connection between two ESP32.

[pschatzmann]

You can't use I2S between two ESP32 to transmit audio reliably!

[Prog32aw]

Thanks for the link to the discussion.
Unfortunately, there seems to be no solution for this issue. It seems to be a bug the I2S receiver.
BTW:
Why does a the slave (receiver) needs to have a sample frequency on a synchronous clock driven bus at all? Reading in the data could be realized with a two simple shift registers, selected by ws_pin as DACs will probably do it. If we do not have a clock line, we have to know the frequency like baudrate on asynchonous UARTs.

[Prog32aw]

I investigated a litte bit more, the result is:
The samplerate from the incoming I2s stream has always to be converted to 44100, because the A2DP output seems to be fixed at this bitrate. The tic-sound were buffer overflows, because of the difference between 48000 (i2s in) and 44100 (A2DP out).
I use as mentioned before a webradio streamer s a source on a separate ESP32 and the sample rate of the output depends on the quality of the web radio station. This is no problem when using a DAC like PCM5102 at all.
I saw a sample about resampling but I did not manage it work for my purpose.
I need I2S (48000) -> resample -> 44100 -> A2DPSource.
I viewed a lot of examples, I do not understand the differences between them fully. Sometimes you use a copier, sometimes not. The arguments of the constructors are not self-explaining (for me) and how the objects are to be used together.
Is there something like a general manual how to use the library?

Thanks in advance

[pschatzmann]

What's wrong with the Wiki ?

[Prog32aw]

Nothing wrong with it. It is well explained but covers the basics only.
The difference might be, that you work on these codes for years and I for three days.
I do not understand, why in the resample example there is not copier.copy() instruction.

[Prog32aw]

Oh, I must apologize. I just saw the first chapter and thought this was the whole Wiki - sorry.

I now understand a lot more a got my application to work as intended.

Thanks

[vednildip]

Hi Prog32aw, How you solved this can you share your code please

[Prog32aw]

What do you mean?

ESP32->I2S->ESP32 ?

[vednildip]

Hello [Prog32aw],
As Wi-Fi and BT not work together hence this logic of using two ESP32. meaning for example Wi-Fi URL fetch at one ESP32 outputting I2S (TX) data to another I2S(RX) ESP32 which works Bluetooth bridge for A2DP output .