AI generated first pass

.gitignore

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+.zig-cache/
+zig-out/

.mise.toml

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+[tools]
+zig = "0.15.1"
+zls = "0.15.0"

LICENSE

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+MIT License
+
+Copyright (c) 2025 Emil Lerch
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# Real-time Speech Recognition with Vosk and Zig
+
+This project implements a minimal real-time speech-to-text application using Vosk and Zig.
+
+## Setup
+
+### Prerequisites
+- Zig 0.15.1 (configured via mise)
+- Nix development environment with C compilation tools, ALSA, and audio libraries
+
+### Vosk Model Download
+The application uses the Vosk small English model for speech recognition:
+- **Source**: https://alphacephei.com/vosk/models/vosk-model-small-en-us-0.15.zip
+- **Size**: ~50MB
+- **Language**: English only
+- **Accuracy**: Good for simple sentences and commands
+
+### Installation Steps
+1. Enter nix development environment: `nix develop`
+2. Download Vosk model: `wget https://alphacephei.com/vosk/models/vosk-model-small-en-us-0.15.zip`
+3. Extract model: `unzip vosk-model-small-en-us-0.15.zip`
+4. Build application: `zig build`
+5. Run: `./zig-out/bin/stt`
+
+## Usage
+The application will:
+- Initialize audio capture from default microphone
+- Load the Vosk speech recognition model
+- Process audio in real-time
+- Output recognized text to terminal
+- Exit on Ctrl+C
+
+## Dependencies
+- Vosk C API library
+- ALSA for audio capture
+- Standard C libraries for audio processing

build.zig

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+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
+    const exe = b.addExecutable(.{
+        .name = "stt",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/main.zig"),
+            .target = target,
+            .optimize = optimize,
+        }),
+    });
+
+    exe.linkLibC();
+    exe.addIncludePath(b.path("vosk-linux-x86_64-0.3.45"));
+    exe.addLibraryPath(b.path("vosk-linux-x86_64-0.3.45"));
+    exe.linkSystemLibrary("vosk");
+    exe.linkSystemLibrary("asound");
+
+    b.installArtifact(exe);
+
+    const run_step = b.step("run", "Run the app");
+    const run_cmd = b.addRunArtifact(exe);
+    run_step.dependOn(&run_cmd.step);
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+}

build.zig.zon

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+.{
+    // This is the default name used by packages depending on this one. For
+    // example, when a user runs `zig fetch --save <url>`, this field is used
+    // as the key in the `dependencies` table. Although the user can choose a
+    // different name, most users will stick with this provided value.
+    //
+    // It is redundant to include "zig" in this name because it is already
+    // within the Zig package namespace.
+    .name = ._1_stt_2,
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "0.0.0",
+    // Together with name, this represents a globally unique package
+    // identifier. This field is generated by the Zig toolchain when the
+    // package is first created, and then *never changes*. This allows
+    // unambiguous detection of one package being an updated version of
+    // another.
+    //
+    // When forking a Zig project, this id should be regenerated (delete the
+    // field and run `zig build`) if the upstream project is still maintained.
+    // Otherwise, the fork is *hostile*, attempting to take control over the
+    // original project's identity. Thus it is recommended to leave the comment
+    // on the following line intact, so that it shows up in code reviews that
+    // modify the field.
+    .fingerprint = 0xe6cb5784eea38627, // Changing this has security and trust implications.
+    // Tracks the earliest Zig version that the package considers to be a
+    // supported use case.
+    .minimum_zig_version = "0.15.1",
+    // This field is optional.
+    // Each dependency must either provide a `url` and `hash`, or a `path`.
+    // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+    // Once all dependencies are fetched, `zig build` no longer requires
+    // internet connectivity.
+    .dependencies = .{
+        // See `zig fetch --save <url>` for a command-line interface for adding dependencies.
+        //.example = .{
+        //    // When updating this field to a new URL, be sure to delete the corresponding
+        //    // `hash`, otherwise you are communicating that you expect to find the old hash at
+        //    // the new URL. If the contents of a URL change this will result in a hash mismatch
+        //    // which will prevent zig from using it.
+        //    .url = "https://example.com/foo.tar.gz",
+        //
+        //    // This is computed from the file contents of the directory of files that is
+        //    // obtained after fetching `url` and applying the inclusion rules given by
+        //    // `paths`.
+        //    //
+        //    // This field is the source of truth; packages do not come from a `url`; they
+        //    // come from a `hash`. `url` is just one of many possible mirrors for how to
+        //    // obtain a package matching this `hash`.
+        //    //
+        //    // Uses the [multihash](https://multiformats.io/multihash/) format.
+        //    .hash = "...",
+        //
+        //    // When this is provided, the package is found in a directory relative to the
+        //    // build root. In this case the package's hash is irrelevant and therefore not
+        //    // computed. This field and `url` are mutually exclusive.
+        //    .path = "foo",
+        //
+        //    // When this is set to `true`, a package is declared to be lazily
+        //    // fetched. This makes the dependency only get fetched if it is
+        //    // actually used.
+        //    .lazy = false,
+        //},
+    },
+    // Specifies the set of files and directories that are included in this package.
+    // Only files and directories listed here are included in the `hash` that
+    // is computed for this package. Only files listed here will remain on disk
+    // when using the zig package manager. As a rule of thumb, one should list
+    // files required for compilation plus any license(s).
+    // Paths are relative to the build root. Use the empty string (`""`) to refer to
+    // the build root itself.
+    // A directory listed here means that all files within, recursively, are included.
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+        // For example...
+        //"LICENSE",
+        //"README.md",
+    },
+}

flake.lock

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+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1757347588,
+        "narHash": "sha256-tLdkkC6XnsY9EOZW9TlpesTclELy8W7lL2ClL+nma8o=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "b599843bad24621dcaa5ab60dac98f9b0eb1cabe",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  description = "Vosk speech recognition development environment";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            clang
+            llvm
+            cmake
+            pkg-config
+            zlib
+            alsa-lib
+            alsa-plugins
+            SDL2
+          ];
+
+          shellHook = ''
+            export ALSA_PLUGIN_DIR=${pkgs.alsa-plugins}/lib/alsa-lib
+          '';
+        };
+      });
+}

src/main.zig

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+const std = @import("std");
+const c = @cImport({
+    @cInclude("vosk_api.h");
+    @cInclude("alsa/asoundlib.h");
+});
+
+const SAMPLE_RATE = 16000;
+const BUFFER_SIZE = 4000;
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+
+    // Initialize Vosk
+    c.vosk_set_log_level(-1);
+    const model = c.vosk_model_new("vosk-model-small-en-us-0.15");
+    if (model == null) {
+        std.debug.print("Failed to load model\n", .{});
+        return;
+    }
+    defer c.vosk_model_free(model);
+
+    const rec = c.vosk_recognizer_new(model, SAMPLE_RATE);
+    if (rec == null) {
+        std.debug.print("Failed to create recognizer\n", .{});
+        return;
+    }
+    defer c.vosk_recognizer_free(rec);
+
+    // Try to open default capture device
+    var handle: ?*c.snd_pcm_t = null;
+    var err = c.snd_pcm_open(&handle, "default", c.SND_PCM_STREAM_CAPTURE, c.SND_PCM_NONBLOCK);
+    if (err < 0) {
+        std.debug.print("Cannot open default audio device: {s}\n", .{c.snd_strerror(err)});
+        std.debug.print("Make sure no other applications are using the microphone\n", .{});
+        return;
+    }
+    defer _ = c.snd_pcm_close(handle);
+
+    // Set to blocking mode
+    err = c.snd_pcm_nonblock(handle, 0);
+    if (err < 0) {
+        std.debug.print("Cannot set blocking mode: {s}\n", .{c.snd_strerror(err)});
+        return;
+    }
+
+    // Configure audio - try simple parameters first
+    err = c.snd_pcm_set_params(handle, c.SND_PCM_FORMAT_S16_LE, c.SND_PCM_ACCESS_RW_INTERLEAVED, 1, SAMPLE_RATE, 1, 100000);
+    if (err < 0) {
+        std.debug.print("Cannot configure audio: {s}\n", .{c.snd_strerror(err)});
+        return;
+    }
+
+    std.debug.print("Audio configured successfully\n", .{});
+    std.debug.print("Listening... (Ctrl+C to exit)\n", .{});
+
+    var buffer: [BUFFER_SIZE]i16 = undefined;
+    var frame_count: u32 = 0;
+    
+    while (true) {
+        const frames = c.snd_pcm_readi(handle, &buffer, BUFFER_SIZE / 2);
+        if (frames < 0) {
+            std.debug.print("Audio read error: {s}\n", .{c.snd_strerror(@intCast(frames))});
+            err = c.snd_pcm_recover(handle, @intCast(frames), 0);
+            if (err < 0) {
+                std.debug.print("Cannot recover from error: {s}\n", .{c.snd_strerror(err)});
+                break;
+            }
+            continue;
+        }
+
+        frame_count += 1;
+        if (frame_count % 50 == 0) {
+            // Show we're getting audio data
+            var max_sample: u16 = 0;
+            for (0..@intCast(frames)) |i| {
+                const abs_sample = @abs(buffer[i]);
+                if (abs_sample > max_sample) {
+                    max_sample = abs_sample;
+                }
+            }
+            std.debug.print("Audio: {} frames, max level: {}\n", .{ frames, max_sample });
+        }
+
+        const result = c.vosk_recognizer_accept_waveform(rec, @ptrCast(&buffer), @intCast(frames * 2));
+        if (result != 0) {
+            const text = c.vosk_recognizer_result(rec);
+            std.debug.print("RECOGNIZED: {s}\n", .{text});
+        }
+    }
+}

src/root.zig

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+//! By convention, root.zig is the root source file when making a library.
+const std = @import("std");
+
+pub fn bufferedPrint() !void {
+    // Stdout is for the actual output of your application, for example if you
+    // are implementing gzip, then only the compressed bytes should be sent to
+    // stdout, not any debugging messages.
+    var stdout_buffer: [1024]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
+    const stdout = &stdout_writer.interface;
+
+    try stdout.print("Run `zig build test` to run the tests.\n", .{});
+
+    try stdout.flush(); // Don't forget to flush!
+}
+
+pub fn add(a: i32, b: i32) i32 {
+    return a + b;
+}
+
+test "basic add functionality" {
+    try std.testing.expect(add(3, 7) == 10);
+}