Mbrola adaptation for microcontrollers

Please be patient... work in progress!

This is not fork of Mbrola, but completely different program, containing big parts of Mbrola code. It's designed especially for microcontollers with small amount of RAM and 8 MB flash (4 MB for some voices).

I assume you are familiar with Mbrola, so I won't explain what is phoneme, details of input text format etc.

This program (library) is provided for ESP32 and Arduino IDE, but main part of library is written in plain C. You probably will be able to use C library (esprola.c file) without changes with Espressif SDK, and porting to other microcontrollers should be limited to replace only some lines (reading flash content).

This library needs board with 8 minimum MB flash (like some ESP32 WROVER boards), but some voices (for example Polish) may be installed on 4 MB board.

This library is intended to use with ESP8266Audio.

Before use of this library you must download original Mbrola voice and convert it into binary or source format used by this library. For debian-like distribution you can simply install voice using apt:

sudo apt install mbrola-<voice_name>

For example: to install us1 (American female voice) use:

sudo apt install mbrola-us1

For other distribution see documentation of your package manager, or download voice from https://github.com/numediart/MBROLA-voices

You must convert voice using voice2c tool (from tools folder). After then, edit config.h file and put correct folder name in _data_header(x) definition.

For Polish (full quality and compiled-in Alaw compressed) voices download prepared data from mimbrola_voices_pl.

This library uses raw flash partition to store voice data. Before compilation you must prepare partition scheme, adding mbrola partition. It must be big enough to hold file espola.blob, must be named mbrola, have type data and subtype 0x40. Use mbrgenpart.py tool from tools folder to create partition description file, extra lines for your boards.txt file and example command for uploading blob into your ESP32 board.

to be continued...