🎬 recs: the Universal Recorder 🎬

Why should there be a record button at all?

A long time ago, I asked myself, "Why is there a record button and the possibility of missing a take? Why not record everything?"

I sometimes play music, and I have mixed bands live, and I wanted a program that would simply record everything at all times which I didn't have to stop and start, that I could run completely separately from my other music programs.

Separately, I wanted to digitize a huge number of cassettes and LPs, so I wanted a program that ran in the background and recorded everything except silence, so I just play the music into the machine, and have it divided into pieces

Nothing like that existed so I wrote it.

recs: the Universal Recorder

recs records any or every audio input on your machine, intelligently filters out quiet, and stores the results in named, organized files.

Free, open-source, configurable, light on CPU and memory, and bulletproof

Bulletproof?

It's not difficult to record some audio. Writing a program that runs continuously and records audio even as real-world things happen is considerably harder.

It is impossible to prevent all loss, but considerable ingenuity and pulling of cables has been used to mitigate and minimize this through software. See Appendix A.

Universal?

It is a "Universal Recorder" because the plan to be able to record all streams of data: audio is simply the start.

I have already written code to do this for MIDI and DMX

• it works well but it isn't productionized, and I'll be folding that in in due time, but most of the difficulty and most of the value in this first step is the audio, so I have focused on just audio for this first release!

It might be that video is also incorporated in the far future, but the tooling is just not there for Python yet, and it would be much too heavy to sit in the background all the time and almost be forgotten about, so you could call it an Almost Universal Recorder if you liked.

Installation

recs is a standard PyPi package - use poetry add recs or pip install recs or your favorite package manager.

To test, type recs --info, which prints JSON describing the input devices you have. Here's a snippet from my machine:

[
    {
        "name": "FLOW 8 (Recording)",
        "index": 1,
        "hostapi": 0,
        "max_input_channels": 10,
        "max_output_channels": 4,
        "default_low_input_latency": 0.01,
        "default_low_output_latency": 0.004354166666666667,
        "default_high_input_latency": 0.1,
        "default_high_output_latency": 0.0136875,
        "default_samplerate": 48000.0
    },
    {
        "name": "USB PnP Sound Device",
        "index": 2,
        ...
    },
    ...
]

Basic Usage

Pick your nicest terminal program, go to a favorite directory with some free space, and type:

recs

recs will start recording all the active audio channels into your current directory and display the results in the terminal.

What "active" means can be customized rather a lot, but by default when a channel becomes too quiet for more than a short time, it stops recording, and will start a new recording automatically when the channel receives a signal.

Some care is taken to preserve the quiet before the start or after the end of a recording to prevent abrupt transitions.

Appendix A: Failure modes

1. Hardware crash or power loss
2. Segfault or similar C/C++ errors

The aim is to be as bulletproof as possible. The pre-beta existing as I write this (2023/11/19) seems to handle harder cases like hybernation well, and can detect if a device goes offline and report it.

The holy grail is reconnecting to a device that comes back online: this is an unsolved problem in Python, I believe, but I am on my way to solving it.