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…
In all my demo sketches so far, I have used just one decoder only, but what if we want to play multiple audio file types ? To support this scenario, I decided to provide the MultiDecoder class, that lets you register your codecs with the corresponding mime type. This class Read more…
MP3 files can contain metadata that stores information about the title, the author etc. If you send an MP3 stream with metadata to a decoder, the logic is usually resilient enough to skip this automatically. However there can be some cases where the codec can’t cope and is crashing. One Read more…
I am providing an Arduino MP3 and AAC decoder library for Arduino which is based on libhelix. In this library I added a simple Arduino inspired C++ API. This was one of my first libraries and I found my implementation quite confusing. So it was time to do some refactoring Read more…
So far I used my arduino-audiokit library together with my AudioTools when I wanted to work with my AudioKit board. This library was a just quick and dirty adaptation of the drivers that were made available by the Espressif ADF framework to Arduino. But it had the following major drawbacks Read more…
This week I was looking into the FAAD AAC Decoder and tried to make it work on the ESP32. I was struggling quite a bit with the memory requirements and I could only make it work with a stack of 60k and by using PSRAM. So to fulfill the stack Read more…
At the very beginning of my Arduino AudioTools project, I was providing a codec for WAV files. It was just handling PCM audio, so it just needed to read or write the header and then could just copy the audio data. In my last blog, I was writing that the Read more…
My AudioTools project is supporting quite a few audio encoders and decoders. They are critical to reduce the storage or transmission volume of audio. Though I support the encoding of AAC and MP3, I can’t really recommend this: it requires a lot of memory and processing time. For an introduction Read more…
In my last post I was writing about audio containers. But containers are usually also used to mux audio and video together in one file. This made me think, if we could play movies on an ESP32? In fact there are some projects out there that exactly do this: They Read more…
So far I have created quite a few posts about the supported codecs, but I never provided any detailed information how things work behind the scene. Audio codecs are used to compress and decompress PCM audio data. I tried to eliminate all the complexity but sometimes it helps to know Read more…