Using libFLAC on ESP32 with PCM5102A for 44.1/16/2 audio

[geoffw64]

Hi Phil, Hope you're well.
I'm using the libFLAC library you very kindly ported for Arduino IDE :)

My setup is Adafruit Huzzah32 with ESP32 WROOM32 and an Adafruit Adalogger with SanDisk Ultra Extreme Pro SD card. I have connected a PCM5102A DAC board and have soldered the FMT jumper to LOW.
A sketch sending sine wave samples to the DAC from memory at 44.1kHz 16-bit 2 channel produces clean sound, so I think my hardware setup is ok.
However, when I read a 44.1kHz 16-bit 2 channel flac audio file from an SD card and decode it using libFLAC, the sound is choppy and has artefacts.
I tested the speed of the SD card in a stand-alone sketch and it reads the entire 26MB audio file in 71 seconds, reading chunks into an 8KB buffer. This is roughly 370 Kbytes/sec or 3Mbps; much faster than the actual playback time.
Questions..

1. Have you found that you need to pre-read audio data from files on SD into memory so that the decoder isn't waiting each time is runs read_callback?
2. Does anything look astray with my i2s config or libFLAC callbacks below?
   i2s_config_t i2s_config = {
   .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX),
   .sample_rate = SAMPLE_RATE,
   .bits_per_sample = (i2s_bits_per_sample_t)BITS_PER_SAMPLE,
   .channel_format = (i2s_channel_fmt_t)I2S_CHANNEL_FMT_RIGHT_LEFT, // 2 channels
   .communication_format = (i2s_comm_format_t)I2S_COMM_FORMAT_I2S, // Set for external DAC
   .intr_alloc_flags = ESP_INTR_FLAG_LEVEL2, // Set interrupt priority
   .dma_buf_count = BUFFER_COUNT,
   .dma_buf_len = BUFFER_LEN,
   .use_apll = false // Does not use audio clock
   };

Here are my read and write callbacks with relevant definitions:
#define SAMPLE_RATE 44100 // Samples per second (per channel)
#define BITS_PER_SAMPLE I2S_BITS_PER_SAMPLE_16BIT // 16 bits per sample
#define BUFFER_COUNT 2 // Number of DMA buffers
#define NUM_CHANNELS 2 // Stereo
#define SAMPLE_LEN_BYTES (BITS_PER_SAMPLE / 8) // Size in bytes of a single sample for one channel
#define SAMPLES_PER_BUFFER 4 // Number of samples to be written to buffer for each channel
#define BUFFER_ELEMENTS (SAMPLES_PER_BUFFER * NUM_CHANNELS) // Number of elements needed to hold contents of buffer
#define BUFFER_LEN (BUFFER_ELEMENTS * SAMPLE_LEN_BYTES) // Length of each DMA buffer in bytes
int16_t i2s_buffer_16[BUFFER_ELEMENTS]; // Buffer used to hold 16-bit signed sample values

FLAC__StreamDecoderReadStatus read_callback(
const FLAC__StreamDecoder* decoder,
FLAC__byte flac_buffer[],
size_t* bytes,
void* client_data) {
if (final) {
bytes = 0; // Zero bytes passed to decoder
final = false;
return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
}
// Executes if not final
bytes = file.read(flac_buffer, bytes); // Read bytes up to provided buffer size from file
if (!file.available()) {
final = true; // End of file reached
}
return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
}
FLAC__StreamDecoderWriteStatus write_callback(
const FLAC__StreamDecoder decoder,
const FLAC__Frame frame,
const FLAC__int32 const flac_buffer[],
void* client_data) {
FLAC__FrameHeader header = frame -> header;
uint32_t blocksize = header.blocksize;
const FLAC__int32* audio_samples_ptr_0 = flac_buffer[0]; // Pointer holding address of decoded samples for channel 0
const FLAC__int32* audio_samples_ptr_1 = flac_buffer[1]; // Pointer holding address of decoded samples for channel 1
const FLAC__int32* end_of_buffer_ptr = flac_buffer[0] + blocksize; // Pointer to end of channel 0 sample array
while (audio_samples_ptr_0 != end_of_buffer_ptr) { // Check for end of array; assumes same number of samples in each channel
FLAC__int32 sample = *audio_samples_ptr_1 / 8; // Attenuate the original sample.
i2s_buffer_16[buf_el] = i2s_buffer_16[buf_el + 1] = (int16_t)sample; // Set value for channel 0 and 1
if (buf_el == BUFFER_ELEMENTS) {
write_i2s_buffer(); // Buffer is full; write it out
buf_el = 0; // Reset counter to start filling buffer again
} else
buf_el += 2; // Recognise 2 samples added to buffer

++audio_samples_ptr_0;              // Increment both pointers along the arrays
++audio_samples_ptr_1;

} // end while
return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
}

I run the decoding and i2s processing in a high priority task. APPLICATION_CPU is defined as 1
xTaskCreatePinnedToCore(audio_task, "audio_task", 8 * 1024, NULL, configMAX_PRIORITIES - 1, NULL, APPLICATION_CPU);

Sorry for the long post! and thanks in advance!
Cheers, Geoff.

[pschatzmann]

I suggest to compare your result with my example sketch: Just replace the AudioBoardStream with an regular I2SStream.

If this is giving the same bad result you will need to check the encoing of your files: I think a level of 0 (fastest) or 1 gives the best result and an ESP32 might not be powerfull enough to handle 8 (best quality).

Using the AudioTools has the advantage that you don't need to rewrite your sketch if you move to the latest ESP 3.0.1 core version.

[geoffw64]

Thanks Phil, I appreciate your time.
The example sketch does produce better sound so something is not right with my sketch. I can only listen to a couple of seconds though, as my power amp has no volume control :) . To listen for longer I'll need to reduce volume. I set about using VolumeStream and read through an example.
The FLACDecoder isn't accepted by the EncodedAudioStream constructor. I guess this is because it's a decoder not an audio stream. Do I need to decode the FLAC to I2S using StreamCopy first, and then feed that stream into EncodedAudioStream? I looked through the examples but couldn't find one with a similar use case.
Your audio tools are awesome. I can see you've done a lot of work. The only reason I'm writing my own FLAC player is that I plan to port it to Raspberry Pi as part of a broader project.

[pschatzmann]

To add volume control, just wrap I2S with a VolumeStream and use the VolumeStream as output.

You can compile an AudioTools sketch on Rasperrry Pi as well...

[geoffw64]

Ah, so simple, thanks. That works very nicely and the sound is actually pretty good through my ICEpower amplifier and KEF Q10 speakers in my office. No dropouts at all playing through a track.
Thanks for letting me know that AudioTools compiles on Pi. I will give it a try when I've done a bit more on the ESP32.

[geoffw64]

Coffee is on the way :)

[geoffw64]

Hey Phil,
Just wondering why you haven't implemented the FLAC__stream_decoder_finish() function in CodecFLAC?
This seems to be the recommended way to decode multiple files eg if playing a series of songs from a list. The function de-initializes the decoder, so you can call initialize again.
Or is there another way to decode multiple flac files without constructing a new decoder each time?
Cheers,
Geoff.

[pschatzmann]

It is my expectation that you can just assign a new file and continue with the copy()

[geoffw64]

Thought I tried that but perhaps I called begin() again. I shall test.
Cheers, Geoff.

[geoffw64]

Hi Phil,
Tried assigning a new file and continuing to copy. Here is the output:
VolumeStream.h : 199 - setVolume: 1.000000 at 0
09:33:22.500 -> [I] VolumeStream.h : 199 - setVolume: 1.000000 at 1
09:33:22.500 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:33:22.500 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:33:22.500 -> [I] CodecFLAC.h : 85 - FLAC is open
09:33:22.500 -> [I] AudioTypes.h : 127 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
09:33:22.500 -> [I] AudioTypes.h : 127 - sample_rate: 44100 / channels: 2 / bits_per_sample: 16
09:33:22.500 -> [I] I2SConfigESP32.h : 80 - rx/tx mode: TX_MODE
09:33:22.500 -> [I] I2SConfigESP32.h : 81 - port_no: 0
09:33:22.500 -> [I] I2SConfigESP32.h : 82 - is_master: Master
09:33:22.500 -> [I] I2SConfigESP32.h : 83 - sample rate: 44100
09:33:22.500 -> [I] I2SConfigESP32.h : 84 - bits per sample: 16
09:33:22.500 -> [I] I2SConfigESP32.h : 85 - number of channels: 2
09:33:22.500 -> [I] I2SConfigESP32.h : 86 - signal_type: Digital
09:33:22.500 -> [I] I2SConfigESP32.h : 88 - i2s_format: I2S_STD_FORMAT
09:33:22.500 -> [I] I2SConfigESP32.h : 90 - auto_clear: true
09:33:22.500 -> [I] I2SConfigESP32.h : 92 - use_apll: true
09:33:22.500 -> [I] I2SConfigESP32.h : 97 - buffer_count:6
09:33:22.500 -> [I] I2SConfigESP32.h : 98 - buffer_size:512
09:33:22.500 -> [I] I2SConfigESP32.h : 103 - pin_bck: 14
09:33:22.500 -> [I] I2SConfigESP32.h : 105 - pin_ws: 15
09:33:22.500 -> [I] I2SConfigESP32.h : 107 - pin_data: 22
09:33:22.533 -> Now playing: /Music/03 Toto - Georgy Porgy.flac
09:33:22.533 -> [I] VolumeStream.h : 199 - setVolume: 0.120000 at 0
09:33:22.533 -> [I] VolumeStream.h : 199 - setVolume: 0.120000 at 1
09:37:41.009 -> [E] CodecFLAC.h : 109 - not active
09:37:41.042 -> Now playing: /Music/09 Toto - Hold The Line.flac
09:37:41.042 -> [E] CodecFLAC.h : 109 - not active
09:37:41.042 -> Now playing: /Music/01 Talking Heads - Psycho Killer.flac
09:37:41.042 -> [E] CodecFLAC.h : 109 - not active
09:37:41.042 -> Now playing: /Music/06 Steely Dan - Hey Nineteen.flac
09:37:41.042 -> [E] CodecFLAC.h : 109 - not active
09:37:41.042 -> Now playing: /Music/01 Dire Straits - So Far Away.flac
09:37:41.042 -> [E] CodecFLAC.h : 109 - not active

The decoder becomes inactive when it completes streaming the first flac file. How can I continue playback without constructing a new decoder? Should the ..._finish() function be implemented? If you make a change I will test it.
Here is my sketch:

#include <SPI.h>
#include <SD.h>
#include "AudioTools.h"
#include "AudioI2S/I2SStream.h"
#include "AudioCodecs/CodecFLAC.h"

const int chipSelect=33;
I2SStream I2S_stream;
I2SConfig I2S_config;
VolumeStream volume_stream(I2S_stream);
FLACDecoder dec;
File music_dir;
File music_file;

void setup() {
Serial.begin(115200);
while (!Serial)
delay(1);
delay(200);
AudioLogger::instance().begin(Serial, AudioLogger::Info);
// setup FLAC decoder
//dec.setOutput(I2S_stream); // Sends stream with volume unchanged
volume_stream.begin(I2S_config); // Provides bits_per_sample and channels
dec.setOutput(volume_stream); // Sends stream with reduced volume
dec.begin();
// setup I2S before SD
I2S_config = I2S_stream.defaultConfig(TX_MODE);
I2S_stream.begin(I2S_config);
// setup SD
SD.begin(chipSelect);
music_dir = SD.open("/Music");
if (!music_dir) {
Serial.println("Could not open Music directory");
while(1);
}
}

void play(File music_file) {
// Plays a music file
dec.setInput(music_file); // Set the input music file
volume_stream.setVolume(0.12); // Set volume
while (dec.copy()); // Decode and send to DAC
}
void loop() {
File music_file = music_dir.openNextFile();
if (music_file) {
Serial.print("Now playing: ");
Serial.println(music_file.name());
play(music_file);
} else {
while(1); // No more music to play
}
}

[pschatzmann]

I extended the begin() logic a bit, so that the decoder gets closed with FLAC__stream_decoder_finish when it is open before calling FLAC__stream_decoder_init_stream.

So just call dec.begin() again after assigning a new file.

[geoffw64]

Hi Phil,
Thanks for the update. Unfortunately it doesn't work because is_active is (probably quite rightly) set to false in the read_callback when eof is reached:
if (self->isEof(*bytes)){
result = FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
self->is_active = false;
}

Here is the Serial output:
09:27:41.594 -> [I] VolumeStream.h : 199 - setVolume: 1.000000 at 1
09:27:41.594 -> [I] AudioTypes.h : 127 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
09:27:41.594 -> [I] AudioTypes.h : 127 - sample_rate: 44100 / channels: 2 / bits_per_sample: 16
09:27:41.594 -> [I] I2SConfigESP32.h : 80 - rx/tx mode: TX_MODE
09:27:41.594 -> [I] I2SConfigESP32.h : 81 - port_no: 0
09:27:41.594 -> [I] I2SConfigESP32.h : 82 - is_master: Master
09:27:41.594 -> [I] I2SConfigESP32.h : 83 - sample rate: 44100
09:27:41.594 -> [I] I2SConfigESP32.h : 84 - bits per sample: 16
09:27:41.594 -> [I] I2SConfigESP32.h : 85 - number of channels: 2
09:27:41.594 -> [I] I2SConfigESP32.h : 86 - signal_type: Digital
09:27:41.594 -> [I] I2SConfigESP32.h : 88 - i2s_format: I2S_STD_FORMAT
09:27:41.594 -> [I] I2SConfigESP32.h : 90 - auto_clear: true
09:27:41.594 -> [I] I2SConfigESP32.h : 92 - use_apll: true
09:27:41.594 -> [I] I2SConfigESP32.h : 97 - buffer_count:6
09:27:41.594 -> [I] I2SConfigESP32.h : 98 - buffer_size:512
09:27:41.594 -> [I] I2SConfigESP32.h : 103 - pin_bck: 14
09:27:41.594 -> [I] I2SConfigESP32.h : 105 - pin_ws: 15
09:27:41.594 -> [I] I2SConfigESP32.h : 107 - pin_data: 22
09:27:41.628 -> Now playing: /Music/03 Toto - Georgy Porgy.flac
09:27:41.628 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:27:41.628 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:27:41.628 -> [I] CodecFLAC.h : 85 - FLAC is open
09:27:41.628 -> [I] VolumeStream.h : 199 - setVolume: 0.120000 at 0
09:27:41.628 -> [I] VolumeStream.h : 199 - setVolume: 0.120000 at 1
09:32:00.055 -> [E] CodecFLAC.h : 109 - not active
09:32:00.165 -> Now playing: /Music/09 Toto - Hold The Line.flac
09:32:00.165 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:32:00.165 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:32:00.165 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:32:00.165 -> [E] CodecFLAC.h : 109 - not active
09:32:00.165 -> Now playing: /Music/01 Talking Heads - Psycho Killer.flac
09:32:00.165 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:32:00.165 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:32:00.165 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:32:00.165 -> [E] CodecFLAC.h : 109 - not active
09:32:00.165 -> Now playing: /Music/06 Steely Dan - Hey Nineteen.flac
09:32:00.165 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:32:00.165 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:32:00.165 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:32:00.165 -> [E] CodecFLAC.h : 109 - not active
09:32:00.165 -> Now playing: /Music/01 Dire Straits - So Far Away.flac
09:32:00.165 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:32:00.165 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:32:00.165 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:32:00.165 -> [E] CodecFLAC.h : 109 - not active
09:27:41.594 -> [I] VolumeStream.h : 199 - setVolume: 1.000000 at 1
09:27:41.594 -> [I] AudioTypes.h : 127 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
09:27:41.594 -> [I] AudioTypes.h : 127 - sample_rate: 44100 / channels: 2 / bits_per_sample: 16
09:27:41.594 -> [I] I2SConfigESP32.h : 80 - rx/tx mode: TX_MODE
09:27:41.594 -> [I] I2SConfigESP32.h : 81 - port_no: 0
09:27:41.594 -> [I] I2SConfigESP32.h : 82 - is_master: Master
09:27:41.594 -> [I] I2SConfigESP32.h : 83 - sample rate: 44100
09:27:41.594 -> [I] I2SConfigESP32.h : 84 - bits per sample: 16
09:27:41.594 -> [I] I2SConfigESP32.h : 85 - number of channels: 2
09:27:41.594 -> [I] I2SConfigESP32.h : 86 - signal_type: Digital
09:27:41.594 -> [I] I2SConfigESP32.h : 88 - i2s_format: I2S_STD_FORMAT
09:27:41.594 -> [I] I2SConfigESP32.h : 90 - auto_clear: true
09:27:41.594 -> [I] I2SConfigESP32.h : 92 - use_apll: true
09:27:41.594 -> [I] I2SConfigESP32.h : 97 - buffer_count:6
09:27:41.594 -> [I] I2SConfigESP32.h : 98 - buffer_size:512
09:27:41.594 -> [I] I2SConfigESP32.h : 103 - pin_bck: 14
09:27:41.594 -> [I] I2SConfigESP32.h : 105 - pin_ws: 15
09:27:41.594 -> [I] I2SConfigESP32.h : 107 - pin_data: 22
09:27:41.628 -> Now playing: /Music/03 Toto - Georgy Porgy.flac
09:27:41.628 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:27:41.628 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:27:41.628 -> [I] CodecFLAC.h : 85 - FLAC is open
09:27:41.628 -> [I] VolumeStream.h : 199 - setVolume: 0.120000 at 0
09:27:41.628 -> [I] VolumeStream.h : 199 - setVolume: 0.120000 at 1
09:32:00.055 -> [E] CodecFLAC.h : 109 - not active
09:32:00.165 -> Now playing: /Music/09 Toto - Hold The Line.flac
09:32:00.165 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:32:00.165 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:32:00.165 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:32:00.165 -> [E] CodecFLAC.h : 109 - not active
09:32:00.165 -> Now playing: /Music/01 Talking Heads - Psycho Killer.flac
09:32:00.165 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:32:00.165 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:32:00.165 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:32:00.165 -> [E] CodecFLAC.h : 109 - not active
09:32:00.165 -> Now playing: /Music/06 Steely Dan - Hey Nineteen.flac
09:32:00.165 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:32:00.165 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:32:00.165 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:32:00.165 -> [E] CodecFLAC.h : 109 - not active
09:32:00.165 -> Now playing: /Music/01 Dire Straits - So Far Away.flac
09:32:00.165 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:32:00.165 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:32:00.165 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:32:00.165 -> [E] CodecFLAC.h : 109 - not active

Relevant functions in my sketch:
void play(File music_file) {
// Plays a music file
dec.setInput(music_file); // Set the input music file
dec.begin(); // Start the decoder
volume_stream.setVolume(0.12); // Set volume
while (dec.copy()); // Decode and send to DAC
}
void loop() {
File music_file = music_dir.openNextFile();
if (music_file) {
Serial.print("Now playing: ");
Serial.println(music_file.name());
play(music_file);
} else {
while(1); // No more music to play
}
}

[pschatzmann]

Ok, I see: I replaced the checking logic to use FLAC__stream_decoder_get_state() instead of is_active

[geoffw64]

Unfortunately this doesn't work.
The read_callback correctly sets result to ...END_OF_STREAM but this doesn't set the decoder state to ...UNINITIALIZED.
if (self->isEof(*bytes)){
result = FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
self->is_active = false;
}

Looking at libFLAC, it seems to be necessary to call ...DECODER_FINISH() to set the state to ...UNINITIALIZED .

[pschatzmann]

I don't quite understand ?
I was running your test and for me it was working as expected:

11:04:53.148 -> [I] I2SConfigESP32V1.h : 89 - pin_data: 26
11:04:53.148 -> [I] I2SESP32V1.h : 201 - tx: 26, rx: -1
11:04:53.148 -> [I] VolumeStream.h : 199 - setVolume: 1.000000 at 0
11:04:53.180 -> [I] VolumeStream.h : 199 - setVolume: 1.000000 at 1
11:04:53.180 -> Now playing: test0.flac
11:04:53.180 -> [I] CodecFLAC.h : 62 - virtual bool audio_tools::FLACDecoder::begin()
11:04:53.212 -> [I] CodecFLAC.h : 94 - FLAC is open
11:04:53.212 -> [I] VolumeStream.h : 199 - setVolume: 0.120000 at 0
11:04:53.212 -> [I] VolumeStream.h : 199 - setVolume: 0.120000 at 1
11:10:52.949 -> [E] CodecFLAC.h : 122 - not active
11:10:53.058 -> Now playing: test1.flac
11:10:53.058 -> [I] CodecFLAC.h : 62 - virtual bool audio_tools::FLACDecoder::begin()
11:10:53.058 -> [I] CodecFLAC.h : 94 - FLAC is open
11:16:52.802 -> [E] CodecFLAC.h : 122 - not active
11:16:52.802 -> Now playing: test2.flac
11:16:52.802 -> [I] CodecFLAC.h : 62 - virtual bool audio_tools::FLACDecoder::begin()
11:16:52.802 -> [I] CodecFLAC.h : 94 - FLAC is open

You can avoid the 'not active' Error message above with

while (dec) dec.copy();

[geoffw64]

Hmmm, I must be doing something stupid.
With this code:
void play(File music_file) {
// Plays a music file
dec.setInput(music_file); // Set the input music file
dec.begin();
volume_stream.setVolume(0.10); // Set volume
while (dec.copy()); // Decode and send to DAC
}
void loop() {
File music_file = music_dir.openNextFile();
if (music_file) {
Serial.print("Now playing: ");
Serial.println(music_file.name());
play(music_file);
} else {
while(1); // No more music to play
}
}
I get this output:
09:41:41.376 -> [I] VolumeStream.h : 199 - setVolume: 1.000000 at 1
09:41:41.376 -> [I] AudioTypes.h : 127 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
09:41:41.376 -> [I] AudioTypes.h : 127 - sample_rate: 44100 / channels: 2 / bits_per_sample: 16
09:41:41.376 -> [I] I2SConfigESP32.h : 80 - rx/tx mode: TX_MODE
09:41:41.376 -> [I] I2SConfigESP32.h : 81 - port_no: 0
09:41:41.376 -> [I] I2SConfigESP32.h : 82 - is_master: Master
09:41:41.376 -> [I] I2SConfigESP32.h : 83 - sample rate: 44100
09:41:41.376 -> [I] I2SConfigESP32.h : 84 - bits per sample: 16
09:41:41.376 -> [I] I2SConfigESP32.h : 85 - number of channels: 2
09:41:41.376 -> [I] I2SConfigESP32.h : 86 - signal_type: Digital
09:41:41.376 -> [I] I2SConfigESP32.h : 88 - i2s_format: I2S_STD_FORMAT
09:41:41.376 -> [I] I2SConfigESP32.h : 90 - auto_clear: true
09:41:41.376 -> [I] I2SConfigESP32.h : 92 - use_apll: true
09:41:41.376 -> [I] I2SConfigESP32.h : 97 - buffer_count:6
09:41:41.376 -> [I] I2SConfigESP32.h : 98 - buffer_size:512
09:41:41.376 -> [I] I2SConfigESP32.h : 103 - pin_bck: 14
09:41:41.376 -> [I] I2SConfigESP32.h : 105 - pin_ws: 15
09:41:41.376 -> [I] I2SConfigESP32.h : 107 - pin_data: 22
09:41:41.410 -> Now playing: /Music/03 Toto - Georgy Porgy.flac
09:41:41.410 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:41:41.410 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:41:41.410 -> [I] CodecFLAC.h : 85 - FLAC is open
09:41:41.410 -> [I] VolumeStream.h : 199 - setVolume: 0.100000 at 0
09:41:41.410 -> [I] VolumeStream.h : 199 - setVolume: 0.100000 at 1
09:45:59.879 -> [E] CodecFLAC.h : 109 - not active
09:45:59.946 -> Now playing: /Music/09 Toto - Hold The Line.flac
09:45:59.946 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:45:59.946 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:45:59.946 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:45:59.946 -> [E] CodecFLAC.h : 109 - not active
09:45:59.946 -> Now playing: /Music/01 Talking Heads - Psycho Killer.flac
09:45:59.946 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:45:59.946 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:45:59.946 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:45:59.946 -> [E] CodecFLAC.h : 109 - not active
09:45:59.946 -> Now playing: /Music/06 Steely Dan - Hey Nineteen.flac
09:45:59.946 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:45:59.946 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:45:59.946 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:45:59.946 -> [E] CodecFLAC.h : 109 - not active
09:45:59.946 -> Now playing: /Music/01 Dire Straits - So Far Away.flac
09:45:59.946 -> [I] CodecFLAC.h : 60 - virtual bool audio_tools::FLACDecoder::begin()
09:45:59.980 -> [I] CodecFLAC.h : 70 - FLAC__stream_decoder_new
09:45:59.980 -> [E] CodecFLAC.h : 81 - ERROR: initializing decoder: FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
09:45:59.980 -> [E] CodecFLAC.h : 109 - not active

This is different to your output.
I am using the latest zip from github and the begin() function in CodecFLAC.h is:
bool begin() {
TRACEI();
is_active = false;
if (decoder == nullptr) {
if ((decoder = FLAC__stream_decoder_new()) == NULL) {
LOGE("ERROR: allocating decoder");
is_active = false;
return false;
}
LOGI("FLAC__stream_decoder_new");
}

// if it is already active we close it
auto state = FLAC__stream_decoder_get_state(decoder);
if (state != FLAC__STREAM_DECODER_UNINITIALIZED){
  FLAC__stream_decoder_finish(decoder);
}

// deactivate md5 checking
FLAC__stream_decoder_set_md5_checking(decoder, is_md5_checing);

// init decoder
if (is_ogg){
  init_status = FLAC__stream_decoder_init_ogg_stream( decoder, read_callback, nullptr, nullptr, nullptr, nullptr, write_callback, nullptr, error_callback, this);
} else {
  init_status = FLAC__stream_decoder_init_stream( decoder, read_callback, nullptr, nullptr, nullptr, nullptr, write_callback, nullptr, error_callback, this);
}

if (init_status != FLAC__STREAM_DECODER_INIT_STATUS_OK) {
  LOGE("ERROR: initializing decoder: %s", FLAC__StreamDecoderInitStatusString[init_status]);
  is_active = false;
  return false;
}
LOGI("FLAC is open");
is_active = true;
return true;

}

Any idea what is different?
NB: I am using an old arduino core. Board is ESP32 Huzzah32.

[pschatzmann]

The line numbers of the logging does not match with the actual code.
So you must be using some old library version somewhere...

[geoffw64]

Correct. Deleted the libraries, downloaded and re-compiled - now works.
Thanks for your help Phil. :)