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pschatzmann / arduino-libhelix

A simple MP3 and AAC Decoder (not only) for Arduino based on libhelix
GNU General Public License v3.0
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low bitrate playback quality issues #5

Closed goatzillax closed 10 months ago

goatzillax commented 10 months ago

I've been playing around with the arduino-audio-tools to use it for audio notification with MP3 files through a bluetooth speaker.

My test project is here:

https://github.com/goatzillax/a2dp_mp3/

It's really just the player example, but I'm playing from LittleFS on an ESP32 (MH-ET Minikit).

The source files are pretty low bitrate -- 32kb. By default they're practically unplayable, but I noticed one of the other issue reports regarding max frame size, so I tried the opposite and lowered the frame size and that improved things considerably.

However:

  1. This seems pretty fragile
  2. There are still audible artifacts like popping and slight stuttering

Is there anything else to try? WAV files straight of RAM seem fine.

pschatzmann commented 10 months ago

I never even tried to go that low: after all the lowest range that is offered by Audacity is 145-185! Google gives the following: The MP3 format can range from around 96 to 320Kbps!

So either use a more normal bitrate or try the other codecs

goatzillax commented 10 months ago

OK, I updated the bitrate to 96k. It still seems to pop and stutter.

I'll poke around the other codecs.

pschatzmann commented 10 months ago

If you are looking for an efficient codec on microcontrollers: adpcm might be a better choice...