D3+D4: export stage PCM16/24 + TPDF dither + noise shaping, resample 44.1/48/96k, normalize -1dBTP/-14LUFS, mono side/mid check; Export modal mastering options + /plugins/render options (test 9 case, 23 passed)

app/core/render_engine.py

@@ -375,6 +375,31 @@ def _probe_track_latency(track, sample_rate):
                 except Exception:
                     pass
 
+def _quantize_pcm(audio, bits, dither):
+    """Quantize float [-1,1] to PCM grid (bits=16|24), optional TPDF dither +
+    1st-order noise shaping. Tra ve int array de sf.write ghi EXACT bits
+    (libsndfile float->PCM khong round dung 32768-grid - kiem chung D3)."""
+    N = 2 ** (bits - 1)
+    x = audio.astype(np.float64)
+    if dither and bits < 32:
+        lsb = 1.0 / N
+        rng = np.random.default_rng()
+        d = (rng.random(x.shape) + rng.random(x.shape) - 1.0) * lsb  # TPDF [-lsb, lsb]
+        out = np.empty_like(x)
+        err = np.zeros(x.shape[0])
+        for i in range(x.shape[1]):
+            s = x[:, i] + d[:, i] + err
+            q = np.rint(s * N)
+            out[:, i] = q
+            err = q / N - s  # 1st-order noise shaping feedback
+        q = np.clip(out, -N, N - 1)
+    else:
+        q = np.clip(np.rint(x * N), -N, N - 1)
+    if bits == 16:
+        return q.astype(np.int16)
+    # PCM_24: libsndfile luu top-24-bit cua int32 -> <<8
+    return (q.astype(np.int64) << 8).astype(np.int32)
+
 class PythonRenderEngine:
     def __init__(self, sample_rate=44100):
         self.sample_rate = sample_rate
@@ -765,7 +790,10 @@ class PythonRenderEngine:
 
         return session_buffer
 
-    def render_project(self, project_json: dict, output_filepath: str):
+    def render_project(self, project_json: dict, output_filepath: str,
+                       bit_depth: int = 32, out_sample_rate: int = 0,
+                       dither: bool = False, normalize: bool = False,
+                       normalize_target: str = "-1dbtp"):
         with RENDER_LOCK:
             bpm = project_json["metadata"]["bpm"]
             time_sig_num = project_json["metadata"].get("time_signature_numerator", 4)
@@ -854,6 +882,31 @@ class PythonRenderEngine:
             if max_peak > 1.0:
                 master_buffer /= max_peak
 
-            # Write final output file
-            sf.write(output_filepath, master_buffer.T, self.sample_rate, subtype="FLOAT")
+            # ── D3 export stage: resample / normalize / dither / PCM ──
+            out_sr = out_sample_rate or self.sample_rate
+            if out_sr != self.sample_rate:
+                from scipy.signal import resample_poly
+                g = math.gcd(int(out_sr), int(self.sample_rate))
+                master_buffer = resample_poly(
+                    master_buffer, int(out_sr) // g, int(self.sample_rate) // g, axis=1)
+            if normalize:
+                from app.core import loudness
+                if normalize_target == "-14lufs":
+                    _l = loudness.integrated_lufs(master_buffer, out_sr)
+                    if np.isfinite(_l):
+                        master_buffer *= 10 ** ((-14.0 - _l) / 20.0)
+                else:  # "-1dbtp"
+                    _tp = loudness.true_peak_db(master_buffer, out_sr)
+                    if np.isfinite(_tp):
+                        master_buffer *= 10 ** ((-1.0 - _tp) / 20.0)
+
+            # Write final output file (D3: PCM_16/PCM_24 + dither, FLOAT mac dinh)
+            if bit_depth == 16:
+                sf.write(output_filepath, _quantize_pcm(master_buffer, 16, dither).T,
+                         out_sr, subtype="PCM_16")
+            elif bit_depth == 24:
+                sf.write(output_filepath, _quantize_pcm(master_buffer, 24, dither).T,
+                         out_sr, subtype="PCM_24")
+            else:
+                sf.write(output_filepath, master_buffer.T, out_sr, subtype="FLOAT")
             return output_filepath