The WavePlayer is a free music cloud service.
The interface of the plugin is designed around what is known as the the waveform that is the sound files that are being played through. See Using Flash to play Audio clips.WavePlayer is an incredibly customizable flexible and flexible HTML5 audio plugin designed for WordPress.
Play short audio files using on-chip Flash memory using a conversion tool that reads *.wav files and extracts the data value to setup a C array.
WAVEPLAYER SOFTWARE
There is probably not enough RAM left to also support networking and/or the RTOS in an application, if mbed is doing software only MP3 decoding. There are also some software only MP3 player code examples in the cookbook, but memory for the RAM buffers is a bit limited. Sparkfun makes an MP3 decoder chip breakout board and there are code examples in the cookbook. Using a breadboard, add support for MP3 and other audio format files. Use another direction on the joystick or one of the blue pots to add a volume control. Develop a user interface using the joystick to select files to play. Read the directoryĪnd display files names on the LCD display.
WAVEPLAYER DRIVER
Without a driver circuit or audio amplifier, the volume will probably still be a bit low on most headphones. scale down Analog voltage by 8 for PC speakers More background information can be found in the tutorial on using a speaker for audio output. PC speakers have a built-in audio amplifier circuit to drive the larger speakers. The audio out signal is coming from the mbed's D/A (DAC) and it has been adjusted to the lower voltage levels typically seen on PC audio signals. The sound level will be similar to what you hear when playing audio on the PC.
WAVEPLAYER UPGRADE
Boom Box Upgrade with PC speakersįor more volume, plug in a set of PC speakers to the analog out jack on the mbed application board. A series of high speed digital pulses is produced, but the average voltage value of the digital signal is the desired analog level.The volume is very low on the tiny speaker (about the same as an earphone) and you will need to hold the board close to your ear to hear it. The duty cycle is then set by the analog sample value. The PWM frequency is set to about ten times the highest frequency of the audio signal. It is possible to output audio using PWM and this technique is actually used in a Class D Audio Amplifier. The board's speaker is connected to a PWM output pin (not a D/A output). Copy it to the USB drive before running the demo and insert the USB flash drive into the application board's USB connector. A wave file for the demo is available at sample.wav. The audio out jack can be connected to a set of PC speakers for more volume. It reads a wave file from a USB flash drive, and outputs audio to the tiny onboard speaker (very low volume) and the analog audio out jack. It is based on the earlier mbed cookbook wave player code. Here is a wave player demo setup for the mbed application board.