Crate pmoflac

pmoflac/src/util.rs

@@ -0,0 +1,47 @@
+use crate::pcm::bytes_per_sample;
+
+pub fn interleaved_i32_to_le_bytes(samples: &[i32], bits_per_sample: u8, out: &mut Vec<u8>) {
+    let bytes_per = bytes_per_sample(bits_per_sample);
+    out.clear();
+    out.reserve(samples.len() * bytes_per);
+
+    for &sample in samples {
+        let mut value = sample;
+        if bits_per_sample < 32 {
+            let shift = 32 - bits_per_sample as u32;
+            value = (value << shift) >> shift;
+        }
+        for i in 0..bytes_per {
+            out.push(((value >> (i * 8)) & 0xFF) as u8);
+        }
+    }
+}
+
+pub fn le_bytes_to_interleaved_i32(bytes: &[u8], bits_per_sample: u8) -> Result<Vec<i32>, String> {
+    let bytes_per = bytes_per_sample(bits_per_sample);
+    if bytes.len() % bytes_per != 0 {
+        return Err(format!(
+            "PCM byte stream length {} is not aligned to {} bytes/sample",
+            bytes.len(),
+            bytes_per
+        ));
+    }
+
+    let mut samples = Vec::with_capacity(bytes.len() / bytes_per);
+    let shift = 32 - (bits_per_sample as u32);
+
+    let mut idx = 0;
+    while idx < bytes.len() {
+        let mut value = 0i32;
+        for i in 0..bytes_per {
+            value |= (bytes[idx + i] as i32) << (8 * i);
+        }
+        if bits_per_sample < 32 {
+            value = (value << shift) >> shift;
+        }
+        samples.push(value);
+        idx += bytes_per;
+    }
+
+    Ok(samples)
+}