The Goertzel Algorithm is an optimized Discrete Fourier Transform (DFT) that can detect defined frequencies. It can be used e.g. to identify DTMF keys. DTMF keys conist of 2 tones that can be described by the following diagram: In the Arduino Audio Tools library we can use the GoertzelStream to Read more…
The ResampleStream class of the Arduino Audio Tools project provides some flexible resampling functionality both on the input and the output side. To calculate the values it just uses a simple but efficient linear interpolation. I finally managed to provide an extended ResampleStreamT resampling class that uses some alternative interpolation Read more…
In my last blog, I described you I added M4A support to my Arduino Audio Tools project and how to use it. As highlited we need to access and store the stsz size tabe to play back the audio: a typical size table contains aournd 40 – 80 kbytes, but Read more…
Last week I was asked, if my Arduino Audio Tools project was supporting the playback of M4A files, which it didn’t: but I thought that would be quite a good opportunity to try out Vibe Coding, since this problem space is well documented and quite established it seemed to be Read more…
Overview I am currently supporting quite an extensive list of audio codecs as part of my Arduino Audio Tools Library. I thought that I covered all available open source implementations. However last week, I discovered that there is an open source implementation for the Apple Lossless Audio Codec (ALAC): I Read more…
I published a new release of my TinyFTP library, that I have converted to a header only C++ library and I changed the FTPClient to a templated class so that we can support an automatic session management with different Client implementations. I already provided an simple ftp example in the Read more…
I thought it might be cool to provide a remote control for the AudioPlayer which is part of the Arduino Audio Tools. I did not want to invent a new protocol, so I implemented the HTML interface that has been documented by the KA-Radio project. I am providing a Stream Read more…
In traditional http streaming we can just read a single audio stream and feed it to a decoder. Unfortunatly Http Live Streaming (HLS) adds a lot of additional complexity and overhead. It works by splitting an audiostream into very short segments, which are just a few seconds in length, and Read more…
After we can access the Internet purely using IDF functionality w/o Arduino, the final challange is to provide access to files as Streams! IDF provides the concept of the Virtual File System (VFS): you can mount a file system under a name and access the files of that file system Read more…
In my last post, I described that I have implemented the URLStream class using pure IDF functionality. So you will not be wrong if you expect a working MP3 Internat Player next that just relies on the IDF w/o Arduino. The main.cpp Program Here is the complete IDF program that Read more…