From ce11d2f89d2016ec111a98453db27b2da47c1d8a Mon Sep 17 00:00:00 2001 From: Emil Lerch Date: Tue, 9 Sep 2025 18:36:44 -0700 Subject: [PATCH] add README and update license to match upstream --- LICENSE | 517 +++++++++++++++++++++++++++++++++++++++++-- README.md | 279 +++++++++++++++++++++++ build.zig | 46 +++- ctl_symbols_list.c | 1 + pcm_symbols_list.c | 11 + timer_symbols_list.c | 1 + 6 files changed, 836 insertions(+), 19 deletions(-) create mode 100644 ctl_symbols_list.c create mode 100644 pcm_symbols_list.c create mode 100644 timer_symbols_list.c diff --git a/LICENSE b/LICENSE index 506dadd..8000a6f 100644 --- a/LICENSE +++ b/LICENSE @@ -1,21 +1,504 @@ -MIT License + GNU LESSER GENERAL PUBLIC LICENSE + Version 2.1, February 1999 -Copyright (c) 2025 Emil Lerch + Copyright (C) 1991, 1999 Free Software Foundation, Inc. + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. -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: +[This is the first released version of the Lesser GPL. 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Here is a sample; alter the names: + + Yoyodyne, Inc., hereby disclaims all copyright interest in the + library `Frob' (a library for tweaking knobs) written by James Random + Hacker. + + , 1 April 1990 + Ty Coon, President of Vice + +That's all there is to it! diff --git a/README.md b/README.md index e69de29..b853d60 100644 --- a/README.md +++ b/README.md @@ -0,0 +1,279 @@ +# Static ALSA Library for Zig + +A minimal, self-contained static build of ALSA (Advanced Linux Sound Architecture) designed for embedding in Zig applications. + +## What This Library Provides + +### Included Components +- **Core ALSA**: Configuration, error handling, async operations +- **PCM (Audio Playback/Recording)**: Hardware access, format conversion, routing +- **Control**: Hardware mixer controls, card enumeration +- **Timer**: Hardware timer access +- **Built-in Plugins**: Essential audio processing without dynamic loading + +### Built-in PCM Plugins +- `hw` - Direct hardware access +- `copy` - Simple audio copying +- `linear` - Linear format conversion +- `null` - Null audio sink +- `empty` - Empty audio source +- `adpcm` - ADPCM compression +- `alaw` - A-law compression +- `mulaw` - μ-law compression +- `iec958` - S/PDIF digital audio +- `lfloat` - Linear floating point conversion +- `mmap_emul` - Memory mapping emulation +- `route` - Audio channel routing + +## Limitations + +### What's NOT Included +- **Dynamic Plugin Loading**: No `dlopen()` support - only built-in plugins work +- **Complex Plugins**: No `dmix`, `dsnoop`, `pulse`, `jack` plugins +- **Rate Conversion**: No `rate` plugin (would need external rate converter) +- **Advanced Routing**: No `multi`, `asym` plugins +- **Software Volume**: No `softvol` plugin +- **File I/O**: No `file` plugin for audio recording to disk + +### Audio Limitations +- Only direct hardware access (`hw:X,Y`) and built-in conversions +- No automatic sample rate conversion +- No software mixing of multiple streams +- No PulseAudio/JACK integration + +## Integration into Zig Projects + +### 1. Add as Dependency + +In your `build.zig.zon`: +```zig +.dependencies = .{ + .alsa = .{ + .path = "../path/to/0-alsa-lib", + }, +}, +``` + +### 2. Link in build.zig + +```zig +const std = @import("std"); + +pub fn build(b: *std.Build) void { + const exe = b.addExecutable(.{ + .name = "my-audio-app", + .root_source_file = b.path("src/main.zig"), + .target = target, + .optimize = optimize, + }); + + // Add ALSA dependency + const alsa_dep = b.dependency("alsa", .{}); + const alsa_lib = alsa_dep.artifact("asound"); + + exe.linkLibC(); + exe.linkLibrary(alsa_lib); + exe.addIncludePath(alsa_dep.path("zig-out/include")); + + b.installArtifact(exe); +} +``` + +### 3. Basic Usage Example + +```zig +const std = @import("std"); +const c = @cImport({ + @cInclude("alsa/asoundlib.h"); +}); + +pub fn main() !void { + var pcm: ?*c.snd_pcm_t = null; + + // Open PCM device for recording + const result = c.snd_pcm_open( + &pcm, + "hw:0,0", // Card 0, Device 0 + c.SND_PCM_STREAM_CAPTURE, + 0 + ); + + if (result < 0) { + std.log.err("Cannot open audio device: {s}", .{c.snd_strerror(result)}); + return; + } + defer _ = c.snd_pcm_close(pcm); + + // Configure PCM parameters + var params: ?*c.snd_pcm_hw_params_t = null; + _ = c.snd_pcm_hw_params_malloc(¶ms); + defer c.snd_pcm_hw_params_free(params); + + _ = c.snd_pcm_hw_params_any(pcm, params); + _ = c.snd_pcm_hw_params_set_access(pcm, params, c.SND_PCM_ACCESS_RW_INTERLEAVED); + _ = c.snd_pcm_hw_params_set_format(pcm, params, c.SND_PCM_FORMAT_S16_LE); + _ = c.snd_pcm_hw_params_set_channels(pcm, params, 1); + + var rate: c_uint = 16000; + _ = c.snd_pcm_hw_params_set_rate_near(pcm, params, &rate, null); + _ = c.snd_pcm_hw_params(pcm, params); + + // Read audio data + var buffer: [1024]i16 = undefined; + const frames_read = c.snd_pcm_readi(pcm, &buffer, buffer.len / 2); + std.log.info("Read {} frames", .{frames_read}); +} +``` + +## Configuration + +### ALSA Configuration File + +The library uses ALSA's configuration system. The configuration file defines how device names are resolved and what plugins are available. + +**Critical**: Without proper configuration, even basic `hw:X,Y` device access may fail. + +```bash +# Set custom config path (recommended) +export ALSA_CONFIG_PATH=/path/to/your/alsa.conf + +# Run your application +./my-audio-app + +# Or disable config entirely (hardware-only, may not work) +export ALSA_CONFIG_PATH=/dev/null +``` + +### Example alsa.conf (Minimal Working Configuration) + +This is the minimal configuration needed for `hw:X,Y` device access: + +``` +# Essential: Define the hw PCM type +pcm.hw { + @args [ CARD DEV SUBDEV ] + @args.CARD { + type string + default 0 + } + @args.DEV { + type integer + default 0 + } + @args.SUBDEV { + type integer + default -1 + } + type hw + card $CARD + device $DEV + subdevice $SUBDEV +} + +# Optional: Define default devices +pcm.!default { + type hw + card 0 + device 0 +} + +ctl.!default { + type hw + card 0 +} + +# Optional: Define named devices +pcm.microphone { + type hw + card 3 + device 0 +} +``` + +### Configuration Behavior + +- **With minimal alsa.conf**: `hw:X,Y` device access works +- **Without alsa.conf** (`ALSA_CONFIG_PATH=/dev/null`): May fail with "Unknown PCM" errors +- **With system config**: May fail if it references plugins not built into this static library + +## Device Selection + +### Hardware Device Format +``` +hw:CARD,DEVICE +``` + +Examples: +- `hw:0,0` - Card 0, Device 0 (usually built-in audio) +- `hw:1,0` - Card 1, Device 0 (usually USB audio) +- `hw:3,0` - Card 3, Device 0 (specific USB device) + +### Finding Available Devices + +```bash +# List audio cards +cat /proc/asound/cards + +# List PCM devices +cat /proc/asound/pcm + +# Test device access +aplay -l # playback devices +arecord -l # capture devices +``` + +## Build Configuration + +The library is configured for static linking with these key settings: + +```zig +// In build.zig - these are already set +.HAVE_LIBDL = 1, // Keep dlmisc.c but use static symbols +.BUILD_PCM_PLUGIN_* = "1", // Enable built-in plugins +// PIC undefined // Enable static plugin symbols +``` + +### Compiler Flags +- `-DALSA_STATIC` - Static library build +- `-DBUILD_STATIC_ONLY` - No shared library support +- `-UPIC` - Undefine PIC to enable built-in plugin symbols + +## Troubleshooting + +### Common Issues + +1. **"Unknown PCM device"** + - Device doesn't exist or wrong card/device number + - Check `/proc/asound/cards` and `/proc/asound/pcm` + +2. **"No such device or address"** + - Device is busy or doesn't support the requested format + - Try different sample rate/format or check if device is in use + +3. **"Cannot open shared library [builtin]"** + - PIC is defined - this shouldn't happen with this build + - Indicates dynamic loading attempt (build configuration error) + +### Debug Environment Variables + +```bash +# Enable ALSA debug output +export ALSA_DEBUG=1 + +# Use minimal config +export ALSA_CONFIG_PATH=/dev/null + +# Specify custom config +export ALSA_CONFIG_PATH=./my-alsa.conf +``` + +## Performance Characteristics + +- **Memory**: ~200KB static library +- **Latency**: Direct hardware access (no software mixing overhead) +- **CPU**: Minimal - only format conversion overhead for built-in plugins +- **Compatibility**: Works with any ALSA-compatible hardware + +## License + +This static build follows the original ALSA library licensing (LGPL 2.1+). diff --git a/build.zig b/build.zig index 18e5be9..b5081e2 100644 --- a/build.zig +++ b/build.zig @@ -19,20 +19,33 @@ pub fn build(b: *std.Build) void { .HAVE_SYS_SHM_H = 1, .HAVE_MALLOC_H = 1, .HAVE_LFS = 1, - .HAVE_LIBDL = 1, - .PIC = 1, + .HAVE_LIBDL = 1, // Match native build + // .PIC = 0, // Remove PIC entirely to enable builtin symbols .BUILD_PCM = "1", .BUILD_MIXER = "1", .BUILD_HWDEP = "1", + .ENABLE_STATIC = 1, // Match --enable-static=yes + .ENABLE_SHARED = 0, // Match --enable-shared=no .ALSA_DEVICE_DIRECTORY = "/dev/snd/", .ALSA_CONFIG_DIR = "/usr/share/alsa", .ALSA_PLUGIN_DIR = "/usr/lib/alsa-lib", .SND_MAX_CARDS = 32, + .BUILD_PCM_PLUGIN_ADPCM = "1", + .BUILD_PCM_PLUGIN_ALAW = "1", + .BUILD_PCM_PLUGIN_IEC958 = "1", + .BUILD_PCM_PLUGIN_LFLOAT = "1", + .BUILD_PCM_PLUGIN_MMAP_EMUL = "1", + .BUILD_PCM_PLUGIN_MULAW = "1", + .BUILD_PCM_PLUGIN_RATE = "1", + .BUILD_PCM_PLUGIN_ROUTE = "1", .__SYMBOL_PREFIX = "", ._GNU_SOURCE = 1, .HAVE_GNU_LD = 1, .HAVE_ELF = 1, .HAVE_ASM_PREVIOUS_DIRECTIVE = 1, + .BUILD_STATIC = 1, + .BUILD_PCM_PLUGIN_HW = 1, + .SND_PCM_BUILTIN = 1, }); // Create version.h @@ -102,6 +115,8 @@ pub fn build(b: *std.Build) void { lib.addConfigHeader(config); lib.addIncludePath(upstream.path("include")); + lib.addIncludePath(upstream.path("src/pcm")); // For pcm_rate.h etc + lib.addIncludePath(b.path(".")); // For our pcm_symbols_list.c lib.addIncludePath(version_h.getDirectory()); lib.addIncludePath(asoundlib_h.getDirectory()); @@ -136,17 +151,44 @@ pub fn build(b: *std.Build) void { "src/control/setup.c", "src/control/ctlparse.c", "src/control/eld.c", + "src/control/control_empty.c", // Empty control "src/pcm/pcm.c", "src/pcm/pcm_hw.c", "src/pcm/pcm_params.c", "src/pcm/pcm_misc.c", "src/pcm/pcm_mmap.c", + "src/pcm/pcm_generic.c", + "src/pcm/pcm_simple.c", + "src/pcm/pcm_plug.c", "src/pcm/mask.c", "src/pcm/interval.c", + // Core PCM plugins - must match native build + "src/pcm/pcm_copy.c", + "src/pcm/pcm_linear.c", + "src/pcm/pcm_null.c", + "src/pcm/pcm_empty.c", + "src/pcm/pcm_adpcm.c", + "src/pcm/pcm_alaw.c", + "src/pcm/pcm_mulaw.c", + "src/pcm/pcm_iec958.c", + "src/pcm/pcm_lfloat.c", + "src/pcm/pcm_mmap_emul.c", + "src/pcm/pcm_route.c", + "src/pcm/pcm_plugin.c", // Plugin support functions + "src/pcm/pcm_symbols.c", // Builtin plugin registration + "src/control/control_symbols.c", // Control symbols + "src/timer/timer_symbols.c", // Timer symbols + "src/timer/timer.c", + "src/timer/timer_hw.c", + "src/timer/timer_query.c", + "src/timer/timer_query_hw.c", }, .flags = &.{ "-D_GNU_SOURCE", "-DALSA_LIBRARY_BUILD", + "-DALSA_STATIC", + "-DBUILD_STATIC_ONLY", + "-UPIC", // Explicitly undefine PIC to enable builtin symbols }, }); diff --git a/ctl_symbols_list.c b/ctl_symbols_list.c new file mode 100644 index 0000000..2571ac0 --- /dev/null +++ b/ctl_symbols_list.c @@ -0,0 +1 @@ +// Empty - control_empty is already included in the main list diff --git a/pcm_symbols_list.c b/pcm_symbols_list.c new file mode 100644 index 0000000..9b775eb --- /dev/null +++ b/pcm_symbols_list.c @@ -0,0 +1,11 @@ +&_snd_module_pcm_copy, +&_snd_module_pcm_linear, +&_snd_module_pcm_null, +&_snd_module_pcm_empty, +&_snd_module_pcm_adpcm, +&_snd_module_pcm_alaw, +&_snd_module_pcm_mulaw, +&_snd_module_pcm_iec958, +&_snd_module_pcm_lfloat, +&_snd_module_pcm_mmap_emul, +&_snd_module_pcm_route, diff --git a/timer_symbols_list.c b/timer_symbols_list.c new file mode 100644 index 0000000..757cded --- /dev/null +++ b/timer_symbols_list.c @@ -0,0 +1 @@ +&_snd_module_timer_hw,