EncodedAudioStream ignores configured sample rates, always uses 44100 Hz

[uros117]

EncodedAudioStream ignores configured sample rates, always uses 44100 Hz

Description

When using EncodedAudioStream with encoders like Opus that require specific sample
rates, the configured sample rate is ignored and it always defaults to 44100 Hz,
causing encoder failures with message:

[E] CodecOpus.h : 277 - opus_encoder_create: invalid argument for sample_rate: 44100, channels:2

Steps to Reproduce

1. Create an OpusOggEncoder and EncodedAudioStream
2. Configure audio info with non-44100 Hz sample rate (e.g., 24000 Hz):

   AudioInfo info(24000, 2, 16);
   encoded_stream.setAudioInfo(info);
   encoded_stream.begin(info);

3. Opus encoder fails with: opus_encoder_create: invalid argument for sample_rate:
   44100...

Expected Behavior

The encoder should receive the configured 24000 Hz sample rate.

Actual Behavior

The encoder always receives 44100 Hz regardless of configuration.

Root Cause Analysis

I found two potential issues:

1. EncodedAudioStream::begin() line 362 calls audioInfo() instead of using configured
   values:

return enc_out.begin(audioInfo());  // Uses defaults, not configured values because audioInfo returns enc_out.audioInfo which is
                                    // never changed

2. Missing setAudioInfo override in EncodedAudioStream - it doesn't propagate audio
   info to enc_out:
   // EncodedAudioStream should override setAudioInfo() to call:
   // enc_out.setAudioInfo(info);

Proposed Solutions

Option A: Fix the begin() method to use configured audio info

bool begin() override {
  // is_output_notify = false;
  setupReader();
  ReformatBaseStream::begin();
  return enc_out.begin(ReformatBaseStream::audioInfo());
}

Option B: Add proper setAudioInfo() override to propagate to enc_out

Impact

This affects anyone using:

• Opus encoding (needs 8k, 12k, 16k, 24k, 48k Hz)
• Any non-44100 Hz encoded audio streams

Environment

• Arduino Audio Tools version: tag v1.1.3
• Platform: ESP32
• Codec: OpusOgg (but likely affects others)

What would be the preferred approach to fix this?

Device Description

ESP32-WROVER-E on the Lilygo T-SIM7600X board

Sketch

/**
 * @file      Test.cpp
 * @brief     Minimal reproduction of EncodedAudioStream sample rate bug
 * @author    Uros Filipovic
 * @date      2025-09-15
 *
 * Demonstrates that EncodedAudioStream ignores configured sample rates
 * and always uses 44100 Hz, causing Opus encoder to fail.
 */
#include "utilities.h"
#include "Arduino.h"
#include "AudioTools.h"
#include "AudioTools/AudioCodecs/CodecOpusOgg.h"

// Test configuration - using 24kHz which Opus supports
AudioInfo test_config(24000, 2, 16);

// Simple sine wave for test data
SineWaveGenerator<int16_t> sine_wave(16000);
GeneratedSoundStream<int16_t> sound_source(sine_wave);

// Output to Serial for testing
CsvOutput<int16_t> csv_out(Serial);

// Opus encoder and stream
OpusOggEncoder opus_encoder;
EncodedAudioStream encoded_stream(&csv_out, &opus_encoder);

StreamCopy copier(encoded_stream, sound_source);

void setup() {
  Serial.begin(115200);
  delay(1000);

  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);

  Serial.println("=== EncodedAudioStream Sample Rate Bug Test ===");
  Serial.printf("Configured sample rate: %d Hz\n", test_config.sample_rate);

  // Configure output
  csv_out.begin(test_config);

  // Configure sine wave generator
  sine_wave.begin(test_config, N_C4);

  // Configure Opus encoder
  opus_encoder.config().application = OPUS_APPLICATION_AUDIO;

  // Test 1: setAudioInfo before begin
  Serial.println("\nTest 1: setAudioInfo() then begin()");
  encoded_stream.setAudioInfo(test_config);

  // Test 2: begin with AudioInfo parameter
  Serial.println("Test 2: begin(AudioInfo)");
  bool success = encoded_stream.begin(test_config);

  // Check results
  AudioInfo actual_info = encoded_stream.audioInfo();
  Serial.printf("Expected: %d Hz\n", test_config.sample_rate);
  Serial.printf("Actual: %d Hz\n", actual_info.sample_rate);

  if (success) {
    Serial.println("Opus encoder started successfully");
  } else {
    Serial.println("Opus encoder failed to start");
  }

  if (actual_info.sample_rate != test_config.sample_rate) {
    Serial.println("BUG: Sample rate mismatch detected");
  } else {
    Serial.println("Sample rate preserved correctly");
  }
}

void loop() {
  // Try to copy some data if encoder is working
  AudioInfo current_info = encoded_stream.audioInfo();
  if (current_info.sample_rate == test_config.sample_rate) {
    copier.copy();
  } else {
    delay(1000);
    Serial.println("Encoder not working due to sample rate bug");
  }
}

Other Steps to Reproduce

I cloned the repository with v1.1.3 tag because in the lib folder of the platformio project. The main branch won't compile with error "driver/i2s_pdm.h: No such file or directory".

The output of the test script is:

=== EncodedAudioStream Sample Rate Bug Test ===
Configured sample rate: 24000 Hz
[I] SoundGenerator.h : 167 - SineWaveGenerator::begin(channels=2, sample_rate=24000, frequency=261.63)
[I] SoundGenerator.h : 150 - bool audio_tools::SineWaveGenerator<T>::begin() [with T = short int]
[I] AudioTypes.h : 125 - SoundGenerator: sample_rate: 24000 / channels: 2 / bits_per_sample: 16
[I] Buffers.h : 415 - resize: 4
[I] SoundGenerator.h : 194 - setFrequency: 261.63
[I] SoundGenerator.h : 195 - active: true

Test 1: setAudioInfo() then begin()
[I] AudioTypes.h : 125 - in: sample_rate: 24000 / channels: 2 / bits_per_sample: 16
[I] AudioTypes.h : 125 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
Test 2: begin(AudioInfo)
[I] AudioTypes.h : 125 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
[I] CodecOpusOgg.h : 95 - writeHeader
[E] CodecOpus.h : 277 - opus_encoder_create: invalid argument for sample_rate: 44100, channels:2
Expected: 24000 Hz
Actual: 44100 Hz
Opus encoder failed to start
BUG: Sample rate mismatch detected
Encoder not working due to sample rate bug
Encoder not working due to sample rate bug
Encoder not working due to sample rate bug
Encoder not working due to sample rate bug
Encoder not working due to sample rate bug
...

What is your development environment (incl. core version info)

Platformio with these env versions:

[env]
platform = espressif32@6.11.0
framework = arduino

I have checked existing issues, discussions and online documentation (incl. the Wiki)

• I confirm I have checked existing issues, discussions and online documentation

[pschatzmann]

I can't reproduce your issue with the current main branch

=== EncodedAudioStream Sample Rate Bug Test ===
Configured sample rate: 24000 Hz
[I] SoundGenerator.h : 165 - SineWaveGenerator::begin(channels=2, sample_rate=24000, frequency=261.63)
[I] SoundGenerator.h : 150 - bool audio_tools::SineWaveGenerator<T>::begin() [with T = short int]
[I] AudioTypes.h : 124 - SoundGenerator: sample_rate: 24000 / channels: 2 / bits_per_sample: 16
[I] Buffers.h : 418 - resize: 4
[I] SoundGenerator.h : 194 - setFrequency: 261.63
[I] SoundGenerator.h : 195 - active: true

Test 1: setAudioInfo() then begin()
[I] AudioTypes.h : 124 - in: sample_rate: 24000 / channels: 2 / bits_per_sample: 16
[I] AudioTypes.h : 124 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
[I] AudioTypes.h : 124 -  sample_rate: 24000 / channels: 2 / bits_per_sample: 16
Test 2: begin(AudioInfo)
[I] AudioTypes.h : 124 - out: sample_rate: 24000 / channels: 2 / bits_per_sample: 16
[I] AudioEncoded.h : 75 - virtual void audio_tools::EncodedAudioOutput::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[I] CodecOpusOgg.h : 95 - writeHeader
Expected: 24000 Hz
Actual: 24000 Hz
Opus encoder started successfully

I made the USE_LEGACY_I2S IDF version dependent now, but you can always force it to the requested value.
However, I would recommend that you use a version that provides the actual IDF

[liusida]

I think I found the same issue. here is a reproducible code:

#include <Arduino.h>
#include "AudioTools.h"
#include "AudioTools/AudioLibs/AudioBoardStream.h"
#include "AudioTools/AudioCodecs/CodecMP3Helix.h"

// Audio board and output (ES8311)
AudioBoard board{AudioDriverES8311, NoPins};
AudioBoardStream out(board);
MP3DecoderHelix mp3;
EncodedAudioStream decoded(&out, &mp3);

void setup() {
    Serial.begin(115200);
    while (!Serial) { delay(10); }
    
    Serial.println("=== EncodedAudioStream Bug Test ===");
    
    // Setup logging
    AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Debug);
    AudioDriverLogger.begin(Serial, AudioDriverLogLevel::Debug);

    // Test the bug: begin/end cycles
    Serial.println("Begin 1");
    decoded.begin();
    Serial.println("End 1");
    decoded.end();
    Serial.println("Begin 2");
    decoded.begin();
    Serial.println("End 2");
    decoded.end();

    Serial.println("Test complete. Will not reach here.");
}

void loop() {
    delay(1000);
}

First begin() is ok, but second begin() crashes.

The problem is that in this line:

arduino-audio-tools/src/AudioTools/AudioCodecs/AudioEncoded.h

Line 362 in e30c138

return enc_out.begin(audioInfo());

It ignores the member variable info, but using enc_out.info as the parameter for enc_out to begin.

And when call the begin for the second time, it'll also break an assert that "sample_rate should not be zero"

Here's part of the log:

Begin 1
[D] AudioIO.h : 30 - void audio_tools::TransformationReader<T>::begin(T*, Stream*) [with T = audio_tools::ReformatBaseStream]
[D] AudioEncoded.h : 365 - Potential bug: Here info has sample_rate 44100, audioInfo() has sample_rate 1, but enc_out.info has sample_rate 1.
[D] AudioEncoded.h : 150 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] AudioEncoded.h : 152 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] CodecMP3Helix.h : 128 - virtual void audio_tools::MP3DecoderHelix::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] AudioEncoded.h : 160 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] AudioEncoded.h : 161 - cfg.sample_rate: 1
[D] AudioCodecsBase.h : 29 - virtual void audio_tools::AudioDecoder::setAudioInfo(audio_tools::AudioInfo)
[D] AudioTypes.h : 177 - notifyAudioChange: sample_rate: 1
[I] I2SCodecStream.h : 95 - virtual void audio_tools::I2SCodecStream::setAudioInfo(audio_tools::AudioInfo)
[D] BaseStream.h : 131 - virtual void audio_tools::AudioStream::setAudioInfo(audio_tools::AudioInfo)
[I] AudioTypes.h : 124 - in: sample_rate: 1 / channels: 36 / bits_per_sample: 1
[I] AudioTypes.h : 124 - out: sample_rate: 1 / channels: 36 / bits_per_sample: 1
[D] AudioTypes.h : 177 - notifyAudioChange: sample_rate: 1
[I] I2SStream.h : 96 - virtual void audio_tools::I2SStream::setAudioInfo(audio_tools::AudioInfo)
[D] BaseStream.h : 131 - virtual void audio_tools::AudioStream::setAudioInfo(audio_tools::AudioInfo)
[I] AudioTypes.h : 124 - in: sample_rate: 1 / channels: 36 / bits_per_sample: 1
[I] AudioTypes.h : 124 - out: sample_rate: 1 / channels: 36 / bits_per_sample: 1
[D] AudioTypes.h : 177 - notifyAudioChange: sample_rate: 1
[E] I2SCodecStream.h : 327 - Unsupported bits: 1
[D] I2SCodecStream.h : 332 - RATE_8K
[I] CodecMP3Helix.h : 82 - virtual bool audio_tools::MP3DecoderHelix::begin()
[D] AudioEncoded.h : 163 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] AudioEncoded.h : 165 - virtual bool audio_tools::EncodedAudioOutput::begin()
End 1
[I] AudioEncoded.h : 182 - virtual void audio_tools::EncodedAudioOutput::end()
[D] CodecMP3Helix.h : 93 - virtual void audio_tools::MP3DecoderHelix::end()
Begin 2
[D] AudioIO.h : 30 - void audio_tools::TransformationReader<T>::begin(T*, Stream*) [with T = audio_tools::ReformatBaseStream]
[D] AudioEncoded.h : 365 - Potential bug: Here info has sample_rate 44100, audioInfo() has sample_rate 0, but enc_out.info has sample_rate 0.
[D] AudioEncoded.h : 150 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] AudioEncoded.h : 152 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] CodecMP3Helix.h : 128 - virtual void audio_tools::MP3DecoderHelix::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] AudioEncoded.h : 160 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] AudioEncoded.h : 161 - cfg.sample_rate: 0
[D] AudioCodecsBase.h : 29 - virtual void audio_tools::AudioDecoder::setAudioInfo(audio_tools::AudioInfo)
[D] AudioTypes.h : 177 - notifyAudioChange: sample_rate: 0
[I] I2SCodecStream.h : 95 - virtual void audio_tools::I2SCodecStream::setAudioInfo(audio_tools::AudioInfo)
[D] BaseStream.h : 131 - virtual void audio_tools::AudioStream::setAudioInfo(audio_tools::AudioInfo)
[I] AudioTypes.h : 124 - in: sample_rate: 0 / channels: 0 / bits_per_sample: 0
[I] I2SStream.h : 96 - virtual void audio_tools::I2SStream::setAudioInfo(audio_tools::AudioInfo)

assert failed: virtual void audio_tools::I2SStream::setAudioInfo(audio_tools::AudioInfo) I2SStream.h:97 (info.sample_rate != 0)

[pschatzmann]

I am pretty sure this has already been corrected: did you install the latest main branch ?

[uros117]

I didn't have time to test out the main branch.
I've just read a51f65e and it looks like the problem should be solved because setAudioInfo now calls enc_out.setAudioInfo.
I'll try to do it today or tomorrow night.
Thanks for the quick responses!

[uros117]

I switched to the main branch and executed my example, which worked:

Configured sample rate: 24000 Hz
[I] SoundGenerator.h : 167 - SineWaveGenerator::begin(channels=2, sample_rate=24000, frequency=261.63)
[I] SoundGenerator.h : 150 - bool audio_tools::SineWaveGenerator<T>::begin() [with T = short int]
[I] AudioTypes.h : 125 - SoundGenerator: sample_rate: 24000 / channels: 2 / bits_per_sample: 16
[I] Buffers.h : 418 - resize: 4
[I] SoundGenerator.h : 194 - setFrequency: 261.63
[I] SoundGenerator.h : 195 - active: true

Test 1: setAudioInfo() then begin()
[I] AudioTypes.h : 125 - in: sample_rate: 24000 / channels: 2 / bits_per_sample: 16
[I] AudioTypes.h : 125 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
[I] AudioTypes.h : 125 -  sample_rate: 24000 / channels: 2 / bits_per_sample: 16
Test 2: begin(AudioInfo)
[I] AudioTypes.h : 125 - out: sample_rate: 24000 / channels: 2 / bits_per_sample: 16
[I] AudioEncoded.h : 75 - virtual void audio_tools::EncodedAudioOutput::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[I] CodecOpusOgg.h : 95 - writeHeader
Expected: 24000 Hz
Actual: 24000 Hz
Opus encoder started successfully
Sample rate preserved correctly

I also managed to run @liusida's example. Here is the output:

Begin 1
[D] AudioIO.h : 30 - void audio_tools::TransformationReader<T>::begin(T*, Stream*) [with T = audio_tools::ReformatBaseStream]
[I] AudioEncoded.h : 75 - virtual void audio_tools::EncodedAudioOutput::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] CodecMP3Helix.h : 128 - virtual void audio_tools::MP3DecoderHelix::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] Allocator.h : 76 - Allocated 8
[D] AudioEncoded.h : 156 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] AudioEncoded.h : 158 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] CodecMP3Helix.h : 128 - virtual void audio_tools::MP3DecoderHelix::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] CodecMP3Helix.h : 128 - virtual void audio_tools::MP3DecoderHelix::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] Allocator.h : 76 - Allocated 12
[D] AudioCodecsBase.h : 29 - virtual void audio_tools::AudioDecoder::setAudioInfo(audio_tools::AudioInfo)
[I] CodecMP3Helix.h : 82 - virtual bool audio_tools::MP3DecoderHelix::begin()
End 1
[I] AudioEncoded.h : 185 - virtual void audio_tools::EncodedAudioOutput::end()
[D] CodecMP3Helix.h : 93 - virtual void audio_tools::MP3DecoderHelix::end()
Begin 2
[D] AudioIO.h : 30 - void audio_tools::TransformationReader<T>::begin(T*, Stream*) [with T = audio_tools::ReformatBaseStream]
[I] AudioEncoded.h : 75 - virtual void audio_tools::EncodedAudioOutput::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] CodecMP3Helix.h : 128 - virtual void audio_tools::MP3DecoderHelix::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] AudioEncoded.h : 156 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] AudioEncoded.h : 158 - virtual bool audio_tools::EncodedAudioOutput::begin()
[D] CodecMP3Helix.h : 128 - virtual void audio_tools::MP3DecoderHelix::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] CodecMP3Helix.h : 128 - virtual void audio_tools::MP3DecoderHelix::addNotifyAudioChange(audio_tools::AudioInfoSupport&)
[D] AudioCodecsBase.h : 29 - virtual void audio_tools::AudioDecoder::setAudioInfo(audio_tools::AudioInfo)
[I] CodecMP3Helix.h : 82 - virtual bool audio_tools::MP3DecoderHelix::begin()
End 2
[I] AudioEncoded.h : 185 - virtual void audio_tools::EncodedAudioOutput::end()
[D] CodecMP3Helix.h : 93 - virtual void audio_tools::MP3DecoderHelix::end()
Test complete. Will not reach here.

The sample rate debug information is not present, but it seems to be working.