SHA256
100 lines
4.1 KiB
C#
100 lines
4.1 KiB
C#
using System;
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namespace ADOFAIRenderer.Util.Audio;
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internal static class AudioResampler
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{
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public static float[] Resample(float[] inputSamples, int inputChannels, int inputFrequency, int targetChannels, int targetFrequency)
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{
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// ── Safety Validation ──
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if (inputSamples.Length == 0 ||
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inputChannels <= 0 || targetChannels <= 0 ||
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inputFrequency <= 0 || targetFrequency <= 0)
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{
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return Array.Empty<float>();
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}
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// If format is identical, return original samples
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if (inputFrequency == targetFrequency && inputChannels == targetChannels)
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return inputSamples;
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int inputLength = inputSamples.Length / inputChannels;
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int targetLength = (int)Math.Floor((double)inputLength * targetFrequency / inputFrequency);
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float[] outputSamples = new float[targetLength * targetChannels];
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for (int i = 0; i < targetLength; i++)
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{
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double srcIndex = (double)i * inputFrequency / targetFrequency;
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long idxLow = (long)Math.Floor(srcIndex);
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long idxHigh = idxLow + 1;
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float t = (float)(srcIndex - idxLow);
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if (idxHigh >= inputLength) idxHigh = inputLength - 1;
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if (idxLow >= inputLength) idxLow = inputLength - 1;
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if (targetChannels == 1) // 1. Mono Output
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{
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float valLow, valHigh;
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if (inputChannels == 1) // Mono -> Mono
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{
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valLow = inputSamples[idxLow];
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valHigh = inputSamples[idxHigh];
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}
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else // Multi -> Mono (Downmix: Average all channels)
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{
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float sumLow = 0f;
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float sumHigh = 0f;
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for (int c = 0; c < inputChannels; c++)
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{
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sumLow += inputSamples[idxLow * inputChannels + c];
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sumHigh += inputSamples[idxHigh * inputChannels + c];
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}
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valLow = sumLow / inputChannels;
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valHigh = sumHigh / inputChannels;
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}
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outputSamples[i] = valLow + t * (valHigh - valLow);
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}
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else if (targetChannels == 2) // 2. Stereo Output
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{
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if (inputChannels == 1) // Mono -> Stereo (Duplicate to Left/Right)
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{
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float valLow = inputSamples[idxLow];
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float valHigh = inputSamples[idxHigh];
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float val = valLow + t * (valHigh - valLow);
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outputSamples[i * 2] = val;
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outputSamples[i * 2 + 1] = val;
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}
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else // Stereo/Multi -> Stereo (Map Left/Right, ignore extra channels)
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{
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float valLowL = inputSamples[idxLow * inputChannels];
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float valHighL = inputSamples[idxHigh * inputChannels];
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outputSamples[i * 2] = valLowL + t * (valHighL - valLowL);
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float valLowR = inputSamples[idxLow * inputChannels + 1];
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float valHighR = inputSamples[idxHigh * inputChannels + 1];
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outputSamples[i * 2 + 1] = valLowR + t * (valHighR - valLowR);
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}
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}
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else // 3. Multi-channel Output (e.g., 5.1 Surround)
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{
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for (int c = 0; c < targetChannels; c++)
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{
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float valLow, valHigh;
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if (c < inputChannels)
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{
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valLow = inputSamples[idxLow * inputChannels + c];
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valHigh = inputSamples[idxHigh * inputChannels + c];
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}
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else
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{
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valLow = inputSamples[idxLow * inputChannels];
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valHigh = inputSamples[idxHigh * inputChannels];
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}
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outputSamples[i * targetChannels + c] = valLow + t * (valHigh - valLow);
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}
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}
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}
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return outputSamples;
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}
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} |