Run a decoder#

Every decoder works the same way: mark the time range and channel it should read, start it from its own button, then read the result underneath.

Some audio is not meant for you to listen to. Telephone tones, Morse, and slow-scan television all carry data as sound. A file can also carry a payload in the low bits of its samples, where nobody hears it at all. The Decoders tab turns each of those back into something readable. They all work the same way: pick a time range, run one decoder, and read the result underneath.

The Decoders tab listing DTMF, Morse, SSTV with a Martin M1 mode dropdown, and LSB extract with channel and bit-depth dropdowns, each with its own run button

Select a time range#

A decoder runs over your current selection. With nothing selected, it runs over the whole file. The note at the top of the tab tells you which of the two applies.

To narrow the range, switch the toolbar to Select and drag a region across the spectrogram. You can also hold Shift and drag while you are still in Zoom mode. Make that choice on the spectrogram, because the signal you want usually looks distinctive: Morse as clean bursts on one frequency, DTMF as stacked tone pairs, an SSTV transmission as a slow ragged band that lasts a minute or more.

The channel selected on the toolbar decides which channel the decoder reads. On a stereo file where the signal appears on one side only, set that channel first.

Start a decode#

Each row has its own button. A decode is a single deliberate action, not something that happens as you move around. While a decode runs, the tab reads Decoding… and the buttons stay disabled.

The result appears below the decoder list in its own section, and the app keeps only the most recent one. A different file clears it.

If a decode fails, the reason appears inline in a red callout and also as a notification. A failure that happens while you look elsewhere still reaches you.

Pick the right decoder#