3-Band equalizer not catch sampling rate

[hash6iron]

Hello @pschatzmann.

I try to play a WAV at 11.KHz / 8bits with player. Previous to play the file is adapted sampling rate, channels on player, eq and kitstream (i2s) ... but I noticed that 3-band eq don't it.

Real audio Info is the audio info of the source (WAVdecoder). You can see that Equalizer not change to 11KHz/1 channels.
Why?

Thanks in advance.

My log.

Real Audio Info - Sample Rate: 11025Hz, Bits: 16, Channels: 1
Player - Sample Rate: 11025Hz, Bits: 16, Channels: 1
Equalizer - Sample Rate: 44100Hz, Bits: 16, Channels: 2
KitStream - Sample Rate: 11025Hz, Bits: 16, Channels: 1

[yudin-s]

My guess is that the equalizer is still using its default config because it is not receiving the decoder AudioInfo update.

The 44100 Hz / 2 channels value is the default ConfigEqualizer3Bands. In Equalizer3Bands, the filter coefficients are recalculated in begin(), and setAudioInfo(AudioInfo info) updates sample_rate, channels, and bits_per_sample before calling begin() again. That automatic path only works if the equalizer is in a stream/output chain that receives audio-info notifications.

So I would check two things:

1. How the equalizer is constructed. If it is attached only as a plain Print/stream without audio-change notification, explicitly pass the decoder/player info into the equalizer before playback.
2. The order of begin() calls. The equalizer must be re-begun after the WAV decoder has detected 11025 / 1 / 16; otherwise its coefficients stay at the default 44100 Hz stereo config.

Conceptually the setup should end up doing something equivalent to:

ConfigEqualizer3Bands cfg = eq.defaultConfig();
cfg.sample_rate = 11025;
cfg.channels = 1;
cfg.bits_per_sample = 16;
eq.begin(cfg);

or, better, let the audio pipeline call eq.setAudioInfo(info) from the decoded WAV info.

If you share the small part where player, eq, and kitstream are connected, it should be possible to point to the exact missing notification/rebegin step.

[hash6iron]

I solved forcing eq.begin(..)

Thanks so much

[pschatzmann]

How does your processing chain look like ?
If it is not updated automatically, you can define a link by calling addNotifyAudioChange(Equilizer) on the decoder as decscribed in the documentation.

[hash6iron]

Yes, the auto notification was add, but I don't know the reason due to not working.

[yudin-s]

Since forcing eq.begin(...) fixes it, that strongly points to the notification path rather than the filter itself.

The useful bit to paste back is the small setup section where the decoder/source, eq, and output stream are connected, including the exact addNotifyAudioChange(...) call and where it happens relative to begin(). If the notify link is added to a different object than the one that actually discovers the WAV format, or it is added after playback already started, the equalizer can stay at the default config even though the manual eq.begin(...) path works.

[hash6iron]

Hi again.

I don't know but I continue having problems with 3-band eq and audio chain.

My audio chain is.

Player (working with WAV file) -> EQ -> volumeStream -> kitStream (board)

Player, volumeStream and kitStream are adapted well, sampling rate is detected for them, but EQ not.

[pschatzmann]

I committed a correction, but didn't have the chance to test it...

[hash6iron]

Ok. Thanks @pschatzmann.

I'm going to test now.
Best regards.

[hash6iron]

Hello @pschatzmann.
it seems to work fine but now occurs the same problem with VolumeStream object

[hash6iron]

In this case "VolumeStream" is a global component. Then I would like that VolumeStream could adapt it to the WAV sampling rate and others WAV parameters. How can I do it?

[yudin-s]

The same propagation rule probably applies to VolumeStream.

VolumeStream can adapt when its setAudioInfo(...) is called, but if you wire the chain manually the "Player -> EQ -> VolumeStream -> kitStream" arrows do not automatically mean each object is subscribed to format changes.

So I would check that the object which now receives the WAV AudioInfo also notifies the next stage:

decoder.addNotifyAudioChange(eq);
eq.addNotifyAudioChange(volumeStream);
volumeStream.addNotifyAudioChange(kitStream);

The exact source object may be different in your sketch, but the important part is that VolumeStream must be in the notify chain too. If you build the path with Pipeline, the library code wires those addNotifyAudioChange(...) links between consecutive stages for you.

[hash6iron]

Ok. I have to review the notification chain, because if I add VolumeStream and kitStream, the ESP32 crashes.

[pschatzmann]

I committed some corrections

• Equalizer3Bands: notifications
• VolumeStream: correct reported AudioInfo

and tested with the following sketch:

#include "AudioTools.h"

I2SStream i2s;
Equalizer3Bands eq(i2s);
VolumeStream vol(eq);

void setup() {
  Serial.begin(115200);
  delay(5000);

  // starting with 44100, stereo 16 bits
  Serial.println("starting....");
  vol.begin();
  eq.begin();
  i2s.begin();

  // update audio info to 8000 1 channel
  vol.setAudioInfo(AudioInfo(8000,1,16));

  // check result at end of chain
  AudioInfo info = i2s.audioInfo();
  Serial.println(info.sample_rate);
  Serial.println(info.channels);
}

void loop() {}

[hash6iron]

Hi @pschatzmann .

Now works fine. I have forcing the audioInfo of VolumeStream previous to kitStream and last Equalizer, then playing is ok. I have a doubt. Why "bits_per_sample" in the case of WAV that I have testing (is 8 bits) appears as 16 bits?

I think even the decoder works by default at 16 bits although file is in 8 bits.

Thanks in advanced.

[pschatzmann]

As the documentation describes, the decoder can translate 8 bits audiomatically to 16 bits.

This setting is acive by default and you can deactivate it: Note that none of the other classes will be able to handle the unsigned 8 bits provided by the codec...

[hash6iron]

Ok. Thank you so much. I only want to use with WAV decoding, is perfect.