AudioSPDIF.h

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#pragma once
 
#include "AudioConfig.h"
#include "AudioTools/AudioLogger.h"
#include "AudioTools/AudioStreams.h"
#include "AudioI2S/I2SConfig.h"
#include "AudioI2S/I2SStream.h"
 
// Default Data Pin
#ifndef SPDIF_DATA_PIN
#define SPDIF_DATA_PIN 23
#endif
 
#define I2S_NUM ((i2s_port_t)0)
#define I2S_BITS_PER_SAMPLE (32)
#define I2S_CHANNELS 2
#define BMC_BITS_PER_SAMPLE 64
#define BMC_BITS_FACTOR (BMC_BITS_PER_SAMPLE / I2S_BITS_PER_SAMPLE)
#define SPDIF_BLOCK_SAMPLES 192
#define SPDIF_BUF_DIV 2  // double buffering
#define DMA_BUF_COUNT 2
#define DMA_BUF_LEN                                                  \
  (SPDIF_BLOCK_SAMPLES * BMC_BITS_PER_SAMPLE / I2S_BITS_PER_SAMPLE / \
   SPDIF_BUF_DIV)
#define I2S_BUG_MAGIC (26 * 1000 * 1000)  // magic number for avoiding I2S bug
#define SPDIF_BLOCK_SIZE \
  (SPDIF_BLOCK_SAMPLES * (BMC_BITS_PER_SAMPLE / 8) * I2S_CHANNELS)
#define SPDIF_BUF_SIZE (SPDIF_BLOCK_SIZE / SPDIF_BUF_DIV)
#define SPDIF_BUF_ARRAY_SIZE (SPDIF_BUF_SIZE / sizeof(uint32_t))
 
// BMC preamble
#define BMC_B 0x33173333  // block start
#define BMC_M 0x331d3333  // left ch
#define BMC_W 0x331b3333  // right ch
#define BMC_MW_DIF (BMC_M ^ BMC_W)
#define SYNC_OFFSET 2  // byte offset of SYNC
#define SYNC_FLIP ((BMC_B ^ BMC_M) >> (SYNC_OFFSET * 8))
 
 
namespace audio_tools {
 
/*
 * 8bit PCM to 16bit BMC conversion table, LSb first, 1 end
 */
static const uint16_t bmc_tab_uint[256] = {
    0x3333, 0xb333, 0xd333, 0x5333, 0xcb33, 0x4b33, 0x2b33, 0xab33, 0xcd33,
    0x4d33, 0x2d33, 0xad33, 0x3533, 0xb533, 0xd533, 0x5533, 0xccb3, 0x4cb3,
    0x2cb3, 0xacb3, 0x34b3, 0xb4b3, 0xd4b3, 0x54b3, 0x32b3, 0xb2b3, 0xd2b3,
    0x52b3, 0xcab3, 0x4ab3, 0x2ab3, 0xaab3, 0xccd3, 0x4cd3, 0x2cd3, 0xacd3,
    0x34d3, 0xb4d3, 0xd4d3, 0x54d3, 0x32d3, 0xb2d3, 0xd2d3, 0x52d3, 0xcad3,
    0x4ad3, 0x2ad3, 0xaad3, 0x3353, 0xb353, 0xd353, 0x5353, 0xcb53, 0x4b53,
    0x2b53, 0xab53, 0xcd53, 0x4d53, 0x2d53, 0xad53, 0x3553, 0xb553, 0xd553,
    0x5553, 0xcccb, 0x4ccb, 0x2ccb, 0xaccb, 0x34cb, 0xb4cb, 0xd4cb, 0x54cb,
    0x32cb, 0xb2cb, 0xd2cb, 0x52cb, 0xcacb, 0x4acb, 0x2acb, 0xaacb, 0x334b,
    0xb34b, 0xd34b, 0x534b, 0xcb4b, 0x4b4b, 0x2b4b, 0xab4b, 0xcd4b, 0x4d4b,
    0x2d4b, 0xad4b, 0x354b, 0xb54b, 0xd54b, 0x554b, 0x332b, 0xb32b, 0xd32b,
    0x532b, 0xcb2b, 0x4b2b, 0x2b2b, 0xab2b, 0xcd2b, 0x4d2b, 0x2d2b, 0xad2b,
    0x352b, 0xb52b, 0xd52b, 0x552b, 0xccab, 0x4cab, 0x2cab, 0xacab, 0x34ab,
    0xb4ab, 0xd4ab, 0x54ab, 0x32ab, 0xb2ab, 0xd2ab, 0x52ab, 0xcaab, 0x4aab,
    0x2aab, 0xaaab, 0xcccd, 0x4ccd, 0x2ccd, 0xaccd, 0x34cd, 0xb4cd, 0xd4cd,
    0x54cd, 0x32cd, 0xb2cd, 0xd2cd, 0x52cd, 0xcacd, 0x4acd, 0x2acd, 0xaacd,
    0x334d, 0xb34d, 0xd34d, 0x534d, 0xcb4d, 0x4b4d, 0x2b4d, 0xab4d, 0xcd4d,
    0x4d4d, 0x2d4d, 0xad4d, 0x354d, 0xb54d, 0xd54d, 0x554d, 0x332d, 0xb32d,
    0xd32d, 0x532d, 0xcb2d, 0x4b2d, 0x2b2d, 0xab2d, 0xcd2d, 0x4d2d, 0x2d2d,
    0xad2d, 0x352d, 0xb52d, 0xd52d, 0x552d, 0xccad, 0x4cad, 0x2cad, 0xacad,
    0x34ad, 0xb4ad, 0xd4ad, 0x54ad, 0x32ad, 0xb2ad, 0xd2ad, 0x52ad, 0xcaad,
    0x4aad, 0x2aad, 0xaaad, 0x3335, 0xb335, 0xd335, 0x5335, 0xcb35, 0x4b35,
    0x2b35, 0xab35, 0xcd35, 0x4d35, 0x2d35, 0xad35, 0x3535, 0xb535, 0xd535,
    0x5535, 0xccb5, 0x4cb5, 0x2cb5, 0xacb5, 0x34b5, 0xb4b5, 0xd4b5, 0x54b5,
    0x32b5, 0xb2b5, 0xd2b5, 0x52b5, 0xcab5, 0x4ab5, 0x2ab5, 0xaab5, 0xccd5,
    0x4cd5, 0x2cd5, 0xacd5, 0x34d5, 0xb4d5, 0xd4d5, 0x54d5, 0x32d5, 0xb2d5,
    0xd2d5, 0x52d5, 0xcad5, 0x4ad5, 0x2ad5, 0xaad5, 0x3355, 0xb355, 0xd355,
    0x5355, 0xcb55, 0x4b55, 0x2b55, 0xab55, 0xcd55, 0x4d55, 0x2d55, 0xad55,
    0x3555, 0xb555, 0xd555, 0x5555,
};
static const int16_t *bmc_tab = (int16_t *)bmc_tab_uint;
 
static uint32_t spdif_buf[SPDIF_BUF_ARRAY_SIZE];
static uint32_t *spdif_ptr = nullptr;
 
struct SPDIFConfig : public AudioInfo {
  SPDIFConfig() {
    bits_per_sample = 16;
    channels = 2;
    sample_rate = 44100;
  }
  int port_no = 0;  // processor dependent port
  int pin_data = SPDIF_DATA_PIN;
  int buffer_count = 30;
  int buffer_size = 384;
};
 
class SPDIFOutput : public AudioStream {
 public:
  SPDIFOutput() = default;
 
  virtual ~SPDIFOutput() { end(); }
 
  bool begin() { return begin(cfg); }
 
  bool begin(SPDIFConfig config) {
    TRACED();
    cfg = config;
    // Some validations to make sure that the config is valid
    if (!(cfg.channels == 1 || cfg.channels == 2)) {
      LOGE("Unsupported number of channels: %d", cfg.channels);
      return false;
    }
    if (cfg.bits_per_sample != 16) {
      LOGE("Unsupported bits per sample: %d - must be 16!",
           cfg.bits_per_sample);
      return false;
    }
 
    if (i2sOn) {
      i2s.end();
    }
 
    // initialize S/PDIF buffer
    spdif_buf_init();
    spdif_ptr = spdif_buf;
 
    // Setup I2S
    int sample_rate = cfg.sample_rate * BMC_BITS_FACTOR;
    if (sample_rate==0){
      TRACEE();
      return false;
    }
    int bclk = sample_rate * I2S_BITS_PER_SAMPLE * I2S_CHANNELS;
    int mclk = (I2S_BUG_MAGIC / bclk) * bclk;  // use mclk for avoiding I2S bug
 
    I2SConfig i2s_cfg;
    i2s_cfg.sample_rate = sample_rate;
    i2s_cfg.channels = cfg.channels;
    i2s_cfg.pin_ws = -1;
    i2s_cfg.pin_bck = -1;
    i2s_cfg.pin_data = cfg.pin_data;
    i2s_cfg.buffer_count = cfg.buffer_count;
    i2s_cfg.buffer_size = cfg.buffer_size;
    i2s_cfg.bits_per_sample = I2S_BITS_PER_SAMPLE;
    i2s_cfg.i2s_format = I2S_STD_FORMAT;
    i2s_cfg.rx_tx_mode = TX_MODE;
#ifdef ESP32
    i2s_cfg.use_apll = true;
#  if ESP_IDF_VERSION < ESP_IDF_VERSION_VAL(5, 0 , 0)
    i2s_cfg.fixed_mclk = mclk;
#  endif
#endif
    i2sOn = i2s.begin(i2s_cfg);
    return i2sOn;
  }
 
  void end() {
    TRACED();
    i2s.end();
    i2sOn = false;
  }
 
  void setAudioInfo(AudioInfo info) {
    TRACED();
    if (info.bits_per_sample != 16) {
      LOGE("Unsupported bits per sample: %d - must be 16!",
           info.bits_per_sample);
    }
    if (cfg.bits_per_sample != info.bits_per_sample
    || cfg.channels != info.channels
    || cfg.sample_rate != info.sample_rate
    || !i2sOn) {
      cfg.bits_per_sample = info.bits_per_sample;
      cfg.channels = info.channels;
      cfg.sample_rate = info.sample_rate;
      begin(cfg);
    }
  }
 
  SPDIFConfig defaultConfig() {
    SPDIFConfig c;
    return c;
  }
 
  size_t write(const uint8_t *src, size_t size) {
    if (!i2sOn) return 0;
    const uint8_t *p = src;
    size_t result = 0;
 
    while (p < (uint8_t *)src + size) {
      // convert PCM 16bit data to BMC 32bit pulse pattern
      if (cfg.channels == 2) {
        *(spdif_ptr + 1) =
            (uint32_t)(((bmc_tab[*p] << 16) ^ bmc_tab[*(p + 1)]) << 1) >> 1;
        p += 2;
      } else {
        // must be one channels -> use the same value for both
        *(spdif_ptr + 1) =
            (uint32_t)(((bmc_tab[*p] << 16) ^ bmc_tab[*(p)]) << 1) >> 1;
        p++;
      }
      result += 2;
      spdif_ptr += 2;  // advance to next audio data
 
      if (spdif_ptr >= &spdif_buf[SPDIF_BUF_ARRAY_SIZE]) {
        // set block start preamble
        ((uint8_t *)spdif_buf)[SYNC_OFFSET] ^= SYNC_FLIP;
 
        i2s.write((uint8_t *)spdif_buf, sizeof(spdif_buf));
        spdif_ptr = spdif_buf;
      }
    }
 
    return result;
  }
 
 protected:
  bool i2sOn = false;
  SPDIFConfig cfg;
  I2SStream i2s;
 
  // initialize S/PDIF buffer
  void spdif_buf_init(void) {
    TRACED();
    size_t i;
    uint32_t bmc_mw = BMC_W;
 
    for (i = 0; i < (size_t)SPDIF_BUF_ARRAY_SIZE; i += 2) {
      spdif_buf[i] = bmc_mw ^= BMC_MW_DIF;
    }
  }
};
 
using SPDIFStream = SPDIFOutput;
 
}  // namespace audio_tools