Added flac and mp3 output format.

README.md

@@ -1,13 +1,14 @@
 # tuxrecord2
 
-Record audio to a WAV file on **Linux** using **ALSA** as the recording source.
+Record audio to WAV, FLAC or MP3 files on **Linux** using **ALSA** as the recording source.
 
 `tuxrecord2` is the **Rust** port of `tuxrecord`, the Linux port of the former
 macOS-only **macrecord** tool. The original port was written in C99; this rewrite
 keeps the same command-line interface and behaviour but is implemented in Rust
 on top of the safe [alsa](https://crates.io/crates/alsa) bindings and a small
-amount of `libc` for terminal, polling and signal handling. It builds with
-**Cargo**.
+amount of `libc` for terminal, polling and signal handling. FLAC and MP3 output
+is encoded in real time through small FFI shims over the system `libFLAC` and
+`libmp3lame` libraries. It builds with **Cargo**.
 macrecord was created by my good friend Armin. You can find his code here:
 [https://codeberg.org/armin/macrecord](https://codeberg.org/armin/macrecord)
 
@@ -17,6 +18,12 @@ macrecord was created by my good friend Armin. You can find his code here:
 - ALSA development headers and `pkg-config`
   (`libasound2-dev` on Debian/Ubuntu, `alsa-lib-devel` on Fedora,
   `alsa-lib` on Arch)
+- FLAC and LAME (MP3) development headers and `pkg-config`, used for the
+  bundled real-time encoders
+  (`libflac-dev` and `libmp3lame-dev` on Debian/Ubuntu, `flac-devel` and
+  `lame-devel` on Fedora, `flac` and `lame` on Arch). They are only needed
+  to build; at run time the shared `libFLAC` / `libmp3lame` libraries are
+  used.
 
 ## Usage
 
@@ -36,6 +43,10 @@ tuxrecord2 -p myrec
 # Use a specific ALSA capture device
 tuxrecord2 -D hw:1,0
 
+# Encode to FLAC (lossless) or MP3 (lossy) in real time
+tuxrecord2 -f flac
+tuxrecord2 --format mp3
+
 # Record from PipeWire (the PipeWire sound server)
 tuxrecord2 -D pipewire
 ```
@@ -48,6 +59,7 @@ tuxrecord2 -D pipewire
 | `-d <secs>`    | Stop automatically after `<secs>` seconds                |
 | `-p <prefix>`  | Filename prefix instead of `tuxrecord2`                  |
 | `-D <device>`  | ALSA capture device (default: `default`; `pipewire` on PipeWire systems) |
+| `-f, --format <fmt>` | Output format: `wav`, `flac` or `mp3` (default: `wav`) |
 | `-h, --help`   | Show help                                                |
 
 Run `arecord -l` to list available ALSA capture devices. On systems with
@@ -59,9 +71,26 @@ or `wpctl status` (see "Recording from PipeWire" below).
 - **q** - Stop recording and save the file
 - **Ctrl+C** - Stop recording and save the file
 
-The file is written as `<prefix>__<timestamp>.wav` (default prefix
-`tuxrecord2`). The VU meter shows the input level of the left and right channels
-in real time when stderr is a terminal.
+The file is written as `<prefix>__<timestamp>.<ext>` where `<ext>` is `wav`,
+`flac` or `mp3` depending on `-f/--format` (default prefix `tuxrecord2`). The VU
+meter shows the input level of the left and right channels in real time when
+stderr is a terminal.
+
+## Output formats
+
+Audio is captured once and handed to the selected encoder as it arrives, so
+FLAC and MP3 are produced **in real time** — no intermediate WAV file is
+written and no second conversion pass runs afterwards.
+
+- **wav** (default) — uncompressed 16-bit little-endian PCM in a RIFF/WAVE
+  container.
+- **flac** — lossless compression via libFLAC (streaming, default
+  compression level 5).
+- **mp3** — lossy compression via LAME at a constant 192 kbit/s, quality 2.
+
+`wav` and `flac` preserve the captured stream exactly; `mp3` is lossy. The
+classic 4 GiB RIFF limit applies to `wav` only (the program stops cleanly
+before exceeding it); `flac` and `mp3` have no such limit.
 
 ## Recording system audio
 
@@ -132,9 +161,9 @@ tuxrecord2 -D pipewire
 ```
 
 The `.monitor` source carries exactly what the sink is playing, so anything
-your players output ends up in the WAV file. Every capture follows the same
-`<prefix>__<timestamp>.wav` naming and can be stopped with `q` or **Ctrl+C**.
-The default setting can be restored later with
+your players output ends up in the recorded file. Every capture follows the
+same `<prefix>__<timestamp>.<ext>` naming and can be stopped with `q` or
+**Ctrl+C**. The default setting can be restored later with
 `pactl set-default-source <your-input-source>`.
 
 ### Troubleshooting