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4596f79c95
The previous sine wave cast signed integers into the PCM range, causing jumps at zero transitions. This shifts everything up by the respective maximum signed integer, so that the signed idle zero becomes the unsigned PCM signal's idle half-point and can continuously cover the whole unsigned range. |
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| .. | ||
| hello.raw | ||
| main.c | ||
| Makefile | ||
| README.md | ||
About
This is a manual test, and demo application for DAC DDS.
Usage
This application will initialize the single default DAC DDS channel, and play sine, square, sawtooth waves or a greeting audio on it as requested on the command line.
Typical usage:
> hello
> sine 440 2
Audio source and license
hello.raw is an audio rendition of GeoTrinity saying "Ahoy!". It was obtained from https://en.wikipedia.org/wiki/File:GT_Ahoi_Deutsch_GT.ogg where it is annotated to be licensed under CC-BY-SA 3.0 international.
It was converted and trimmed using:
$ ffmpeg -i GT_Ahoi_Deutsch_GT.ogg -ac 1 -ar 8000 -f u8 -c:a pcm_u8 hello.raw
$ python3 -c "s = open('hello.raw', 'rb').read(); s = s.strip(b'\x80') + b'\x80'; open('hello.raw', 'wb').write(s)"