Introducing DSPi | A powerful, user friendly and open source DSP for less than a cup of coffee

[Wesseling Audio Lab]

thanks

 

[Wesseling Audio Lab]

I installed 1.0.7
I get PDM output signal on the bar along with L/R
no L/R output to DAC
Did that version use different pins?

 

[Weeb Labs]

I installed 1.0.7
I get PDM output signal on the bar along with L/R
no L/R output to DAC
Did that version use different pins?

Yes. The previous architecture used pin 10 for PDM and pin 20 for SPDIF.

 

[Wesseling Audio Lab]

Great Help, Thank you!

I've got L/R sound now but no sub sound. The PDM SUB bar is displaying output - I'm on Pin 10

I'll look things over

 

[capslock]

I'm glad everything is working well. The host is presented with a USB endpoint that specifies 16-bit as the only supported format so it will be handling conversion and dither.

Is this a permanent restriction and if so, will it carry over to SPDIF in or I2S in?

 

[Linards]

Absolutely great work and amazing stuff! ^_^

 

[Rocky Maine]

My intended signal chain is:

PC → DSPi via TOSLINK → DX5 II DAC (speaker PEQ applied) → Cambridge Audio amplifier → Wharfedale Diamond 12.1 loudspeakers
PC → DSPi RCA subwoofer output → BK Electronics XXLS400-FF subwoofer

The missing link would be that my current TV TOSLINK into the DX5 II wont have bass management. The Source has to be a PC from my understanding.

I've been following this thread with interest for a couple days. Just recently I had been thinking of putting my miniDSP back into service but now this is an interesting option.

Then it dawned on me, what is the audio signal source? I'm not sure Kingsnake's comment had been verified (or I missed it).

 

[Weeb Labs]

Great Help, Thank you!

I've got L/R sound now but no sub sound. The PDM SUB bar is displaying output - I'm on Pin 10

I'll look things over

You are very welcome. Is everything working for you now?

I've been following this thread with interest for a couple days. Just recently I had ben thinking of putting my miniDSP back into service but now this is an interesting option.

Then it dawned on me, what is the audio signal source? I'm not sure Kingsnake's comment had been verified (or I missed it).

The source is USB audio. That can be from a PC or any other device with support for USB audio devices.

 

[Rocky Maine]

You are very welcome. Is everything working for you now?


The source is USB audio. That can be from a PC or any other device with support for USB audio devices.

iPad with Lightning to USB adapter? That would be sweet.

Thank you for your hard work on this and sharing it with the community!

 

[Weeb Labs]

iPad with Lightning to USB adapter? That would be sweet.

Thank you for your hard work on this and sharing it with the community!

You are very welcome!

I have not tested that specific combination but it should work.

 

[BeerBear]

Really cool project, congrats!

Total latency is about 10ms.

Why so high? Could it be lowered, without serious compromises?

 

[Weeb Labs]

Really cool project, congrats!


Why so high? Could it be lowered, without serious compromises?

Thank you. 10ms is very low. Much lower than Windows' typical WDM output buffer latency.

 

[BeerBear]

Yeah but Windows WDM is a low bar to be honest.
I was thinking sub 5ms for music making applications.
Unless the 10ms figure includes the host (Mac OS) latency?

 

[TurtlePaul]

Yeah but Windows WDM is a low bar to be honest.
I was thinking sub 5ms for music making applications.
Unless the 10ms figure includes the host (Mac OS) latency?

USB audio is a trade-off between latency and stability. USB packets are sent every 1 ms, so you have at least 1 ms of delay no matter what. Then the device needs to keep a buffer. Since samples are sent in packets but need to be read back at the sample rate of the device, this creates delay. The opposite problem is that the audio device does not know when the next packet will be received and if the buffer gets to zero you get audio dropouts and glitches. A typical DAW buffer is ~128 samples which is nearly 6 ms of delay at 44.1 khz. There is no perfect minimal buffer because depending on system speed, bus contention, DPC latency and myriad other factors, a buffer setting that is fine on one computer will be a glitchy mess on another. The on-device processing and SPDIF transmission is likely only 1-2 ms of delay.

 

[m_g_s_g]

Hi. I've been working on adding an oled VU Meter display to this great project. First results are encouraging.

@Weeb Labs. I'd be happy to issue a PR at some point to your repo, after tidying everything up. In the next days I'll upload everything to my fork first, so anybody can check. Tomorrow is a busy day for me.

NOTE:
- I've forked and ported an existing Arduino project to Pico.
- I'm using a clone Pico 2 and a cheap SSD1306 I2C (two colors), 128*32.

No flu here...

 

[m_g_s_g]

Original project is this.

 

[Weeb Labs]

USB packets are sent every 1 ms, so you have at least 1 ms of delay no matter what.

I'm afraid this is not entirely accurate. The frame interval for USB 1.1 specifically is 1ms but for USB 2.0 (most audio interfaces), microframes are dispatched at an interval of 125uS. Achieving roundtrip latencies below 1ms are entirely possible in a DAW. My daily driver for audio routes various devices through a 32x32 interface with less than 2.2ms of roundtrip latency including DSP.

@BeerBear is correct in that for realtime monitoring of instruments (guitars, keyboards), 10ms is a little bit slow when you take into consideration the fact that it is not an ASIO device and is therefore queued after the existing WDM buffers. Perfectly adequate for all other purposes, though.

Hi. I've been working on adding an oled VU Meter display to this great project. First results are encouraging.

View attachment 511578

@Weeb Labs. I'd be happy to issue a PR at some point to your repo, after tidying everything up. In the next days I'll upload everything to my fork first, so anybody can check. Tomorrow is a busy day for me.

NOTE:
- I've forked and ported an existing Arduino project to Pico.
- I'm using a clone Pico 2 and a cheap SSD1306 I2C (two colors), 128*32.

No flu here...

Very nice! I can't wait to see how it progresses.

I actually have one of these on order for a similar purpose. It's based upon the EP32-S3 and would make a perfect little remote control and VU meter with, a suitably fancy UI. The IMU would enable various volume knob functions, too.

 

[Roland301]

Yeah but Windows WDM is a low bar to be honest.
I was thinking sub 5ms for music making applications.
Unless the 10ms figure includes the host (Mac OS) latency?

I'll buy a Pico and measure the USB audio latency at hardware level (from the point in time that USB data is transmitted to the device).
I'm curious enough about the project already

 

[m_g_s_g]

I actually have one of these on order for a similar purpose. It's based upon the EP32-S3 and would make a perfect little remote control and VU meter with, a suitably fancy UI. The IMU would enable various volume knob f

It looks great! I actually have this other one on hand, I still have not used it. I wanted to first quickly get the low hanging fruits (I2C, SPI oled displays connected to the RPico, maybe the ssd1351 next). I guess by connecting to an ESP32 (serial? I2c?), other options would be open, like using its USB port as host, to connect USB audio interfaces downstream… I look forward to your next iterations!

 

[Luffy]

If you have a Pico 2 (RP2350), then you will need to flash the RP2350 UF2. That should solve your problem.

actually i have only pico 2w( RP2040), it doesnt work on RP2040?