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path: root/src/brr.zig
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const std = @import("std");
const c = @cImport({
    @cInclude("mpg123.h");
    @cInclude("alsa/asoundlib.h");
});

pub fn brr(allocator: std.mem.Allocator, file: []const u8) !void {
    _ = c.mpg123_init();

    const handle = c.mpg123_new(null, null) orelse {
        std.log.warn("Failed to create mpg123 handle\n", .{});
        return;
    };

    const buffer_size = c.mpg123_outblock(handle);

    const file_path: [*c]const u8 = @ptrCast(file);
    if (c.mpg123_open(handle, file_path) != c.MPG123_OK) {
        std.log.warn("Failed to open the file: {s}\n", .{file_path});
        return;
    }

    var pcm: ?*c.snd_pcm_t = undefined;
    if (c.snd_pcm_open(&pcm, "default", c.SND_PCM_STREAM_PLAYBACK, 0) < 0) {
        std.log.warn("Failed to open ALSA device\n", .{});
        return;
    }

    var params: ?*c.snd_pcm_hw_params_t = null;
    if (c.snd_pcm_hw_params_malloc(&params) < 0) {
        std.log.warn("Failed to allocate ALSA hardware parameters\n", .{});
        return;
    }

    var encoding: c_int = 0;
    var channels: c_int = 0;
    var rate: c_long = 0;

    if (c.mpg123_getformat(handle, &rate, &channels, &encoding) != c.MPG123_OK) {
        std.log.warn("Failed to get format\n", .{});
        return;
    }

    _ = c.snd_pcm_hw_params(pcm, params);
    _ = c.snd_pcm_hw_params_set_access(pcm, params, c.SND_PCM_ACCESS_RW_INTERLEAVED);
    _ = c.snd_pcm_hw_params_set_channels(pcm, params, @as(c_uint, @intCast(channels)));
    _ = c.snd_pcm_hw_params_set_rate(pcm, params, @as(c_uint, @intCast(rate)), 0);

    _ = c.snd_pcm_hw_params(pcm, params);

    var buffer: []u8 = try allocator.alloc(u8, buffer_size);
    defer allocator.free(buffer);

    while (true) {
        var done: usize = 0;
        const result = c.mpg123_read(handle, &buffer[0], buffer_size, &done);
        switch (result) {
            c.MPG123_OK => {},
            c.MPG123_DONE => {
                std.log.info("Done reading", .{});
            },
            else => {
                const plain_error = c.mpg123_plain_strerror(result);
                std.log.err("Decode error {s}", .{plain_error});
            },
        }

        if (done == 0) {
            break;
        }

        const write_state = c.snd_pcm_writei(pcm, &buffer[0], done / 2);

        switch (write_state) {
            c.SND_ERROR_BEGIN => {
                std.log.debug("SND_ERROR_BEGIN", .{});
            },
            else => {
                const error_code: c_int = @as(c_int, @intCast(write_state));
                const error_string = c.snd_strerror(error_code);
                std.log.err("Failed {s}", .{error_string});
            },
        }
    }
    _ = c.mpg123_delete(handle);
    _ = c.snd_pcm_hw_params_free(params);
    _ = c.snd_pcm_close(pcm);
    _ = c.mpg123_exit();
}