Introduction Last week, I was asking myself the question how easy or difficult it would be to publish mp3 files via a RTSP server. Quite some time ago, I have extended the Mico-RTSP-Audio project to be integrated with the AudioTools, so all I theoretically needed to do was using Read more
I was always unhappy that just importing my Arduino Audio Tools library was using quite some PROGMEM and RAM even with an empty sketch: Sketch uses 888547 bytes (67%) of program storage space. Maximum is 1310720 bytes. Global variables use 43352 bytes (13%) of dynamic memory, leaving 284328 bytes for Read more
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
Quite some time ago, I published some blogs about the ESP32 PSRAM. I think it is about time to dig a litte deeper into the topic and look at how we can use the unadressable 4 MBytes. PSRAM and C++ STL One thing that took me by surprise when I 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