I converted some Audio C++ libraries into Arduino Libraries and used symlinks which point to the original file locations to make sure that Arduino can find all relevant files. This approach was working fine in OSX and Linux. Unfortunately this seems to create problems in Windows, so I decided to change the approach a little bit and replace the symlinks just with regular files that contain a regular #include. To convert all files manually would Read more…
The ESP32 microcontroller has only a few hundred kilobytes of internal RAM. Fortunately the ESP32 AudioKit or ESP32 Wrover provide 8MB PSRAM where 4MB can be directly addressed. More information how to use PSRAM in Arduino can be found here. The only thing to highlight is that PSRAM can not be allocated in global variables! This is quite unfortunate because I preferably like to do this, so that the compiler can inform about the total Read more…
Per definition ogg files should use the Vorbis file format using Ogg framing. Ogg Vorbis is a fully open, non-proprietary, patent-and-royalty-free, general-purpose compressed audio format for mid to high quality: So it is basically the open source alternative to mp3! xiph.org provides an integer only decoder implementation which is based on pure “C”. I am providing this version as Arduino Library. Like Flac from my last post, the API is using a callback pull mechanism Read more…
I started to work on a FLAC CODEC for my Arduino Audio Tools. FLAC stands for Free Lossless Audio Codec, an audio format similar to MP3, but lossless, meaning that audio is compressed in FLAC without any loss in quality. This is similar to how Zip works, except with FLAC you will get much better compression because it is designed specifically for audio, and you can play back compressed FLAC files in your favorite player Read more…
When I was looking for an alternative open source MP3 decoder, I found the minimp3 project from lieff. Arduino Support Yesterday I took another effort to make it work on an Arduino ESP32. To make the project Arduino compatible was easy: I just had to add library.properties and change the Readme.md to add the instructions. Running the code on the ESP32 however turned out to be not so easy: the sketches were crashing w/o any Read more…
Codecs play an important role in audio streaming, as we have seen in one of my last blogs. I have spent some time to make the Opus Codec available as Arduino Library and I am providing some simple integration from my Arduino Audio Tools library. Opus is a codec for interactive speech and audio transmission over the Internet. Opus can handle a wide range of interactive audio applications, including Voice over IP, videoconferencing, in-game chat, Read more…
Recently I discovered the Micro-RTSP-Audio Project from Thomas Pfitzinger which is based on Micro-RTSP from Kevin Hester. The Real Time Streaming Protocol (RTSP) is an application-level network communication system that transfers real-time data from multimedia to an endpoint device by communicating directly with the server streaming the data. I tried to adapt the library to make sure that it is also compiling in Arduino and converted the example to comply with the Arduino conventions. However Read more…
As we have seen in my last blog, we will need to use a codec to send and receive the audio data with some proper sampling rate: CD quality e.g. is using 44100. I started to collect some promising low-complexity codecs and converted them to Arduino libraries: sbc lc3 aptx g7.22 gsm codec2 As a the next step I will need to provide some nice integration into my Arduino Audio Tools. Arduino Sketches Detailed Information Read more…
This blog continues the topic Low Latency Streaming of Audio Data and we have a closer look at ESP-NOW. This is a protocol developed by Espressif, which enables multiple devices to communicate with one another without using Wi-Fi. I was missing a proper implementation that is based on Arduino Streams, so I have added one to my Arduino Audio Tools Library. Here are the related example Arduino sketches: communication-espnow-send communication-espnow-receive communication-espnow-receive_measure When I was doing Read more…
Introduction Traditional streaming protocols, such as RTSP and RTMP, support low-latency streaming. These are quite complex to implement and I did not find any efficient library which would work properly on a microcontroller e.g. on an ESP32. I tried to migrate the live555 project, but so far I did not manage to have it working properly. We could use Bluetooth with my A2DP library but the lag (of more then half a second) is too Read more…