binkaud: split out common data definitions for the future encoder

[nihav.git] / nihav-rad / src / codecs / binkauddata.rs

diff --git a/nihav-rad/src/codecs/binkauddata.rs b/nihav-rad/src/codecs/binkauddata.rs
new file mode 100644 (file)
index 0000000..1cdce60
--- /dev/null
+++ b/nihav-rad/src/codecs/binkauddata.rs
@@ -0,0 +1,32 @@
+use std::f32::consts;
+
+pub const MAX_BANDS: usize = 25;
+
+const CRITICAL_FREQS: [usize; MAX_BANDS] = [
+      100,   200,  300,  400,  510,  630,   770,   920,
+     1080,  1270, 1480, 1720, 2000, 2320,  2700,  3150,
+     3700,  4400, 5300, 6400, 7700, 9500, 12000, 15500,
+    24500
+];
+
+pub const RUN_TAB: [usize; 16] = [ 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 32, 64 ];
+
+pub fn init_bands(srate: usize, len: usize, num_bands: &mut usize, bands: &mut [usize; MAX_BANDS + 1]) {
+    *num_bands = 1;
+    while *num_bands < CRITICAL_FREQS.len() && CRITICAL_FREQS[*num_bands - 1] < srate {
+        *num_bands += 1;
+    }
+    bands[0] = 2;
+    for i in 1..*num_bands {
+        bands[i] = (CRITICAL_FREQS[i - 1] * len / srate) & !1;
+    }
+    bands[*num_bands] = len;
+}
+
+pub fn get_quants_table() -> [f32; 96] {
+    let mut quants: [f32; 96] = [0.0; 96];
+    for i in 0..quants.len() {
+        quants[i] = ((i as f32) * 0.0664 / consts::LOG10_E).exp();
+    }
+    quants
+}