PurrFX project update 11

Project status overview as of August 28, 2020.

Commits: August 28, 2020.

In today's small update, I added an important feature - support for exporting audio samples in RAW format. Samples exported in this format can be opened for editing by the audacity. Many other programs should also have this capability.
 
Here's how to do it:
1. Start audacity;
2. Select the menu item File ➝ Import ➝ Raw Data;
3. Select the RAW file;
4. Specify the following import options:

Done! The sample can be listened to and edited. In this case, the sound will be slightly different from what the emulator produces, and the reason for this is the mismatch in the playback speed.

To implement export to RAW format, it was necessary to understand how an audio sample works in its original form. It (1-bit delta-encoded sample) should be considered as a sequence of bits, i.e. something like this:
1100101110101111000100001...

The initial signal level is taken to be zero and with each new bit we increase or decrease the signal level. Thus, we get the desired sequence of bytes.

Not that hard, right? As usual, many things just seem complicated. But one has only to get down to business ...


 

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