Flac decoder improvements (#8)

* pass input buffer at each call

* cleanup readme

README.md

@@ -1,7 +1,7 @@
 # esp-audio-libs
 
 A collection of libraries and functions that are useful for playing audio on ESP32 devices. It includes code based on the following:
-- [esp-dsp](https://github.com/espressif/esp-dsp) assembly functions for floating point dot products, Q15 fixed point addition and multipliction by a constant.
+- [esp-dsp](https://github.com/espressif/esp-dsp) assembly functions for floating point dot products and Q15 fixed point addition and constant multipliction.
     - Author: Espressif
     - License: Apache v2.0
 - [ART-resampler](https://github.com/dbry/audio-resampler) for resampling audio, optimized with assembly dot product functions.
@@ -13,7 +13,7 @@ A collection of libraries and functions that are useful for playing audio on ESP
 - [flac-decoder](https://github.com/synesthesiam/flac-decoder) for decoding FLAC files.
     - Author: Michael Hansen
     - License: ESPHome License
-    - Port of [Simple FLACV Decoder (Python)](https://www.nayuki.io/res/simple-flac-implementation/simple-decode-flac-to-wav.py) by Project Nayuki with MIT License
+    - Port of [Simple FLAC Decoder (Python)](https://www.nayuki.io/res/simple-flac-implementation/simple-decode-flac-to-wav.py) by Project Nayuki with MIT License
 - [libHelix MP3 Decoder](https://en.wikipedia.org/wiki/Helix_Universal_Server) for decoding MP3 files
     - Author: Real Networks
     - License: RCSL

include/flac_decoder.h

@@ -49,22 +49,16 @@ const static std::vector<int16_t> FLAC_FIXED_COEFFICIENTS[] = {
  */
 class FLACDecoder {
  public:
-  /* buffer - FLAC data
-   * buffer_size - size of the data buffer
-   * min_buffer_size - min bytes in buffer before fill_buffer is called
-   */
-  FLACDecoder(uint8_t *buffer) : buffer_(buffer) {}
-
   ~FLACDecoder() { this->free_buffers(); }
 
   /* Reads FLAC header from buffer.
    * Must be called before decode_frame. */
-  FLACDecoderResult read_header(size_t buffer_length);
+  FLACDecoderResult read_header(uint8_t *buffer, size_t buffer_length);
 
   /* Decodes a single frame of audio.
    * Copies num_samples into output_buffer.
    * Use get_output_buffer_size() to allocate output_buffer. */
-  FLACDecoderResult decode_frame(size_t buffer_length, int16_t *output_buffer, uint32_t *num_samples);
+  FLACDecoderResult decode_frame(uint8_t *buffer, size_t buffer_length, int16_t *output_buffer, uint32_t *num_samples);
 
   /* Frees internal memory. */
   void free_buffers();

src/decode/flac_decoder.cpp

@@ -8,7 +8,8 @@
 
 namespace flac {
 
-FLACDecoderResult FLACDecoder::read_header(size_t buffer_length) {
+FLACDecoderResult FLACDecoder::read_header(uint8_t *buffer, size_t buffer_length) {
+  this->buffer_ = buffer;
   this->buffer_index_ = 0;
   this->bytes_left_ = buffer_length;
   this->bit_buffer_ = 0;
@@ -240,7 +241,8 @@ FLACDecoderResult FLACDecoder::decode_frame_header_() {
   return FLAC_DECODER_SUCCESS;
 }
 
-FLACDecoderResult FLACDecoder::decode_frame(size_t buffer_length, int16_t *output_buffer, uint32_t *num_samples) {
+FLACDecoderResult FLACDecoder::decode_frame(uint8_t *buffer, size_t buffer_length, int16_t *output_buffer, uint32_t *num_samples) {
+  this->buffer_ = buffer;
   this->buffer_index_ = 0;
   this->bytes_left_ = buffer_length;
   this->out_of_data_ = false;