{"id":6180,"date":"2024-03-26T08:23:44","date_gmt":"2024-03-26T07:23:44","guid":{"rendered":"https:\/\/www.pschatzmann.ch\/home\/?p=6180"},"modified":"2024-03-26T17:10:07","modified_gmt":"2024-03-26T16:10:07","slug":"changing-the-sample-size-to-32-bits-using-a-es9018-dac","status":"publish","type":"post","link":"https:\/\/www.pschatzmann.ch\/home\/2024\/03\/26\/changing-the-sample-size-to-32-bits-using-a-es9018-dac\/","title":{"rendered":"Changing the Sample Size to 32 bits (e.g. for an ES9018 DAC)"},"content":{"rendered":"

There are some DACs out there that only support 32 bits: E.g the ES9018K2M<\/strong> module which is sold as high end HIFI DAC.<\/p>\n

Therefore sometimes it is necessary to change the sample size<\/strong> e.g. from 16 to 32 bits when your codec produces 16 bits.<\/p>\n

This can be easily done with the help of the NumberFormatConverterStream<\/a> class of the Arduino Audio Tools<\/a> library:<\/p>\n

I2SStream i2s; \/\/ final output of decoded stream\nNumberFormatConverterStream fc(i2s); \/\/ write the 16bit data to fc\n\/\/ conigure 16 -> 32 bit\nfc.begin(16, 32);\n<\/code><\/pre>\n
Arduino Sketch<\/h3>\n
Here is a complete sketch of an Internet Radio:<\/p>\n
#include \"AudioTools.h\"\n#include \"AudioCodecs\/CodecMP3Helix.h\"\n\nURLStream url(\"ssid\",\"password\");\nI2SStream i2s; \/\/ final output of decoded stream\nNumberFormatConverterStream nfc(i2s);\nEncodedAudioStream dec(&nfc, new MP3DecoderHelix()); \/\/ Decoding stream\nStreamCopy copier(dec, url); \/\/ copy url to decoder\n\nvoid setup(){\n  Serial.begin(115200);\n  AudioLogger::instance().begin(Serial, AudioLogger::Info);  \n\n  \/\/ convert 16 bits to 32, you could also change the gain\n  nfc.begin(16, 32); \n\n  \/\/ setup i2s\n  auto config = i2s.defaultConfig(TX_MODE);\n  \/\/ you could define e.g your pins and change other settings\n  \/\/config.pin_ws = 10;\n  \/\/config.pin_bck = 11;\n  \/\/config.pin_data = 12;\n  \/\/config.mode = I2S_STD_FORMAT;\n  \/\/config.bits_per_sample = 32; \/\/ we coult do this explicitly\n  i2s.begin(config);\n\n  \/\/ setup I2S based on sampling rate provided by decoder\n  dec.begin();\n\n\/\/ mp3 radio\n  url.begin(\"http:\/\/stream.srg-ssr.ch\/m\/rsj\/mp3_128\",\"audio\/mp3\");\n\n}\n\nvoid loop(){\n  copier.copy();\n}\n\n<\/code><\/pre>\n
The decoder automatically sends any audio format changes to the number format converter which forwards them to i2s. Therefore you end up automatically with the correct sample rate and number of channels w\/o the need to define them in the sketch!<\/p>\n
Please double check the potentially updated code from the examples directory<\/a>.<\/p>\n
Dependencies<\/h2>\n
You need to install the following libraries:<\/p>\n