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Fix overlapping frame iterator behavior #10

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Merged
ElliotBadinger merged 1 commit into from
Oct 7, 2025
Merged

Fix overlapping frame iterator behavior #10

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7 changes: 6 additions & 1 deletion audio/src/main/kotlin/com/siya/epistemophile/audio/dsp/NormalizedFrameIterator.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ class NormalizedFrameIterator(
init {
require(frameSize > 0) { "Frame size must be larger than zero." }
require(shiftAmount > 0) { "Shift size must be larger than zero." }
require(shiftAmount <= frameSize) { "Shift size cannot exceed frame size." }
}

override fun hasNext(): Boolean {
Expand Down Expand Up @@ -51,7 +52,11 @@ class NormalizedFrameIterator(
DoubleVector(data)
} else {
val previous = currentFrame!!.data.clone()
System.arraycopy(data, 0, previous, previous.size - shiftAmount, shiftAmount)
val preserved = previous.size - shiftAmount
if (preserved > 0) {
System.arraycopy(previous, shiftAmount, previous, 0, preserved)
}
System.arraycopy(data, 0, previous, preserved, data.size)
DoubleVector(previous)
}
frameCounter++
Expand Down
10 changes: 9 additions & 1 deletion audio/src/test/kotlin/com/siya/epistemophile/audio/dsp/NormalizedFrameIteratorTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ class NormalizedFrameIteratorTest {
assertEquals(2, frames.size)
val normalization = 0x7fff.toDouble()
val expectedFirst = doubleArrayOf(0.0, 1000 / normalization, 2000 / normalization, 3000 / normalization)
val expectedSecond = doubleArrayOf(0.0, 1000 / normalization, 4000 / normalization, 5000 / normalization)
val expectedSecond = doubleArrayOf(2000 / normalization, 3000 / normalization, 4000 / normalization, 5000 / normalization)
frames[0].forEachIndexed { index, value ->
assertEquals(expectedFirst[index], value, 1e-3)
}
Expand All @@ -51,4 +51,12 @@ class NormalizedFrameIteratorTest {
assertEquals(3000 / 0x7fff.toDouble(), first[2], 1e-3)
assertEquals(0.0, first[3], 1e-6)
}

@Test(expected = IllegalArgumentException::class)
fun `iterator rejects shift larger than frame size`() {
val format = PcmAudioFormat.mono16BitSignedLittleEndian(8000)
val stream = PcmMonoInputStream(format, ByteArrayInputStream(ByteArray(0)))

NormalizedFrameIterator(stream, frameSize = 2, shiftAmount = 3, applyPadding = false)
}
}
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