Fix invalid sample counts in planar audio shrink

src/framework/mlt_audio.c

@@ -320,8 +320,7 @@ void mlt_audio_shrink(mlt_audio self, int samples)
     } else if (plane_count == 1 || samples == 0) {
         // No need to move any data.
         self->samples = samples;
-    }
-    if (plane_count > 1) {
+    } else if (plane_count > 1) {
         // Move data to remove gaps between planes.
         size_t src_plane_size = mlt_audio_plane_size(self);
         self->samples = samples;

src/tests/test_audio/test_audio.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2020 Meltytech, LLC
+ * Copyright (C) 2020-2026 Meltytech, LLC
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -51,6 +51,41 @@ private Q_SLOTS:
         free(data);
         a.set_data(nullptr);
     }
+
+    void ShrinkPlanarAudio_data()
+    {
+        QTest::addColumn<int>("format");
+        QTest::addColumn<int>("samples");
+        QTest::addColumn<QList<int>>("expected");
+
+        const QList<int> unchanged = {11, 12, 13, 14, 21, 22, 23, 24, 31, 32, 33, 34};
+        const QList<int> shrunk = {11, 12, 21, 22, 31, 32};
+        for (auto format : {mlt_audio_s32, mlt_audio_float}) {
+            const QString name = mlt_audio_format_name(format);
+            QTest::newRow(qPrintable(name + "-negative")) << int(format) << -1 << unchanged;
+            QTest::newRow(qPrintable(name + "-same")) << int(format) << 4 << unchanged;
+            QTest::newRow(qPrintable(name + "-larger")) << int(format) << 5 << unchanged;
+            QTest::newRow(qPrintable(name + "-smaller")) << int(format) << 2 << shrunk;
+            QTest::newRow(qPrintable(name + "-zero")) << int(format) << 0 << QList<int>();
+        }
+    }
+
+    void ShrinkPlanarAudio()
+    {
+        QFETCH(int, format);
+        QFETCH(int, samples);
+        QFETCH(QList<int>, expected);
+
+        int32_t data[] = {11, 12, 13, 14, 21, 22, 23, 24, 31, 32, 33, 34};
+        struct mlt_audio_s audio = {};
+        mlt_audio_set_values(&audio, data, 48000, mlt_audio_format(format), 4, 3);
+
+        mlt_audio_shrink(&audio, samples);
+
+        QCOMPARE(audio.samples, int(expected.size()) / 3);
+        for (int i = 0; i < expected.size(); i++)
+            QCOMPARE(data[i], expected[i]);
+    }
 };
 
 QTEST_APPLESS_MAIN(TestAudio)