Initial commit

packages/media/src/qoa.zig

@@ -0,0 +1,50 @@
+const std = @import("std");
+
+const Header = union(enum) {
+    streaming: HeaderStreaming,
+    static: HeaderStatic,
+};
+
+const HeaderStreaming = void;
+
+const HeaderStatic = struct {
+    samples: u32,
+    channels: u8,
+    sample_rate: u24,
+
+    pub fn lengthInSeconds(self: HeaderStatic) f32 {
+        const samples: f64 = @floatFromInt(self.samples);
+        const sample_rate: f64 = @floatFromInt(self.sample_rate);
+        return @floatCast(samples / sample_rate);
+    }
+};
+
+/// The caller asserts that the buffer is at least 12 bytes long, which can
+/// contain the entirety of a QOA file header and the relevant information in
+/// the first frame header.
+pub fn info(buffer: []const u8) ?Header {
+    std.debug.assert(buffer.len >= 12);
+
+    const magic = buffer[0..4];
+    const samples = std.mem.readInt(u32, buffer[4..8], .big);
+    const channels = buffer[8];
+    const sample_rate = std.mem.readInt(u24, buffer[9..12], .big);
+
+    if (!std.mem.eql(u8, magic, "qoaf") or channels == 0 or channels > 8 or sample_rate == 0) {
+        return null;
+    }
+
+    if (samples == 0) {
+        return .{
+            .streaming = {},
+        };
+    } else {
+        return .{
+            .static = .{
+                .samples = samples,
+                .channels = channels,
+                .sample_rate = sample_rate,
+            },
+        };
+    }
+}