Fix

FragmentedRecordWriter/AudioResampler.swift

@@ -103,6 +103,7 @@ public class AudioResampler {
 
     try shift()
 
+    print("mic", inputSampleRate, outputSampleRate)
     let bodyBuffer = underlyingBuffer.advanced(by: numOffsetSamples * 2)
     if inputSampleRate == outputSampleRate {
       copyMonoInt16(bodyBuffer, monoInt16Buffer, numSamples)
@@ -118,6 +119,64 @@ public class AudioResampler {
     self.currentPTS = pts
   }
 
+  public func append(
+    stereoInt16BufferWithSwap: UnsafeMutablePointer<Int16>,
+    numSamples: Int,
+    inputSampleRate: Int,
+    pts: CMTime
+  ) throws {
+    guard
+      inputSampleRate == outputSampleRate || inputSampleRate * 2 == outputSampleRate
+        || inputSampleRate * 6 == outputSampleRate
+    else {
+      throw AudioResamplerError.appendingSampleRateNotSupported
+    }
+
+    try shift()
+
+    let bodyBuffer = underlyingBuffer.advanced(by: numOffsetSamples * 2)
+    if inputSampleRate == outputSampleRate {
+      copyStereoInt16WithSwap(bodyBuffer, stereoInt16BufferWithSwap, numSamples)
+      self.numSamples = numSamples
+    } else if inputSampleRate * 2 == outputSampleRate {
+      copyStereoInt16UpsamplingBy2WithSwap(bodyBuffer, stereoInt16BufferWithSwap, numSamples)
+      self.numSamples = numSamples * 2
+    } else if inputSampleRate * 6 == outputSampleRate {
+      copyStereoInt16UpsamplingBy6WithSwap(bodyBuffer, stereoInt16BufferWithSwap, numSamples)
+      self.numSamples = numSamples * 6
+    }
+
+    self.currentPTS = pts
+  }
+
+  public func append(
+    monoInt16BufferWithSwap: UnsafeMutablePointer<Int16>, numSamples: Int, inputSampleRate: Int,
+    pts: CMTime
+  ) throws {
+    guard
+      inputSampleRate == outputSampleRate || inputSampleRate * 2 == outputSampleRate
+        || inputSampleRate * 6 == outputSampleRate
+    else {
+      throw AudioResamplerError.appendingSampleRateNotSupported
+    }
+
+    try shift()
+
+    let bodyBuffer = underlyingBuffer.advanced(by: numOffsetSamples * 2)
+    if inputSampleRate == outputSampleRate {
+      copyMonoInt16WithSwap(bodyBuffer, monoInt16BufferWithSwap, numSamples)
+      self.numSamples = numSamples
+    } else if inputSampleRate * 2 == outputSampleRate {
+      copyMonoInt16UpsamplingBy2WithSwap(bodyBuffer, monoInt16BufferWithSwap, numSamples)
+      self.numSamples = numSamples * 2
+    } else if inputSampleRate * 6 == outputSampleRate {
+      copyMonoInt16UpsamplingBy6WithSwap(bodyBuffer, monoInt16BufferWithSwap, numSamples)
+      self.numSamples = numSamples * 6
+    }
+
+    self.currentPTS = pts
+  }
+
   public func getCurrentFrame() -> AudioResamplerFrame {
     return AudioResamplerFrame(
       numChannels: 2,

FragmentedRecordWriter/FragmentedAudioWriter.swift

@@ -93,6 +93,10 @@ private class FragmentedAudioWriterDelegate: NSObject, AVAssetWriterDelegate {
 }
 
 public class FragmentedAudioWriter {
+  public var playlistURL: URL {
+    delegate.playlistURL
+  }
+
   private let outputDirectoryURL: URL
   private let outputFilePrefix: String
   private let sampleRate: Int

FragmentedRecordWriter/FragmentedRecordWriter-Bridging-Header.h

@@ -112,3 +112,119 @@ static inline void copyMonoInt16UpsamplingBy6(float *__nonnull dst,
     }
   }
 }
+
+static inline float int16ToFloatWithSwap(int16_t reversedValue) {
+  uint16_t rawValue = *((uint16_t *)&reversedValue);
+  uint16_t rawSwappedValue = (rawValue >> 8) | (rawValue << 8);
+  return INT16_TO_FLOAT(*(int16_t *)&rawSwappedValue);
+}
+
+static inline void copyStereoInt16WithSwap(float *__nonnull dst,
+                                           int16_t *__nonnull src,
+                                           long numSamples) {
+  for (long i = 0; i < numSamples * 2; i++) {
+    dst[i] = int16ToFloatWithSwap(src[i]);
+  }
+}
+
+static inline void copyStereoInt16UpsamplingBy2WithSwap(float *__nonnull dst,
+                                                        int16_t *__nonnull src,
+                                                        long numSamples) {
+  {
+    float x0 = dst[-4];
+    float y0 = dst[-3];
+    float x1 = int16ToFloatWithSwap(src[0]);
+    float y1 = int16ToFloatWithSwap(src[1]);
+    for (long j = 1; j <= 2; j++) {
+      dst[j * 2 - 4] = x0 + (x1 - x0) * j / 2.0;
+      dst[j * 2 - 3] = y0 + (y1 - y0) * j / 2.0;
+    }
+  }
+
+  for (long i = 0; i < numSamples - 1; i++) {
+    float x0 = int16ToFloatWithSwap(src[i * 2 + 0]);
+    float y0 = int16ToFloatWithSwap(src[i * 2 + 1]);
+    float x1 = int16ToFloatWithSwap(src[i * 2 + 2]);
+    float y1 = int16ToFloatWithSwap(src[i * 2 + 3]);
+    for (long j = 1; j <= 2; j++) {
+      dst[i * 4 + j * 2 + 0] = x0 + (x1 - x0) * j / 2.0;
+      dst[i * 4 + j * 2 + 1] = y0 + (y1 - y0) * j / 2.0;
+    }
+  }
+}
+
+static inline void copyStereoInt16UpsamplingBy6WithSwap(float *__nonnull dst,
+                                                        int16_t *__nonnull src,
+                                                        long numSamples) {
+  {
+    float x0 = dst[-12];
+    float y0 = dst[-11];
+    float x1 = int16ToFloatWithSwap(src[0]);
+    float y1 = int16ToFloatWithSwap(src[1]);
+    for (long j = 1; j <= 6; j++) {
+      dst[j * 2 - 12] = x0 + (x1 - x0) * j / 6.0;
+      dst[j * 2 - 11] = y0 + (y1 - y0) * j / 6.0;
+    }
+  }
+
+  for (long i = 0; i < numSamples - 1; i++) {
+    float x0 = int16ToFloatWithSwap(src[i * 2 + 0]);
+    float y0 = int16ToFloatWithSwap(src[i * 2 + 1]);
+    float x1 = int16ToFloatWithSwap(src[i * 2 + 2]);
+    float y1 = int16ToFloatWithSwap(src[i * 2 + 3]);
+    for (long j = 1; j <= 6; j++) {
+      dst[i * 12 + j * 2 + 0] = x0 + (x1 - x0) * j / 6.0;
+      dst[i * 12 + j * 2 + 1] = y0 + (y1 - y0) * j / 6.0;
+    }
+  }
+}
+
+static inline void copyMonoInt16WithSwap(float *__nonnull dst,
+                                         int16_t *__nonnull src,
+                                         long numSamples) {
+  for (long i = 0; i < numSamples; i++) {
+    float x = int16ToFloatWithSwap(src[i]);
+    dst[i * 2] = dst[i * 2 + 1] = x;
+  }
+}
+
+static inline void copyMonoInt16UpsamplingBy2WithSwap(float *__nonnull dst,
+                                                      int16_t *__nonnull src,
+                                                      long numSamples) {
+  {
+    float x0 = dst[-4];
+    float x1 = int16ToFloatWithSwap(src[0]);
+    for (long j = 1; j <= 2; j++) {
+      dst[j * 2 - 4] = dst[j * 2 - 3] = dst[j * 2 - 3] =
+          x0 + (x1 - x0) * j / 2.0;
+    }
+  }
+
+  for (long i = 0; i < numSamples - 1; i++) {
+    float x0 = int16ToFloatWithSwap(src[i + 0]);
+    float x1 = int16ToFloatWithSwap(src[i + 1]);
+    for (long j = 1; j <= 2; j++) {
+      dst[i * 4 + j * 2] = dst[i * 4 + j * 2 + 1] = x0 + (x1 - x0) * j / 2.0;
+    }
+  }
+}
+
+static inline void copyMonoInt16UpsamplingBy6WithSwap(float *__nonnull dst,
+                                                      int16_t *__nonnull src,
+                                                      long numSamples) {
+  {
+    float x0 = dst[-12];
+    float x1 = int16ToFloatWithSwap(src[0]);
+    for (long j = 1; j <= 6; j++) {
+      dst[j * 2 - 12] = dst[j * 2 - 11] = x0 + (x1 - x0) * j / 6.0;
+    }
+  }
+
+  for (long i = 0; i < numSamples - 1; i++) {
+    float x0 = int16ToFloatWithSwap(src[i * 2 + 0]);
+    float x1 = int16ToFloatWithSwap(src[i * 2 + 2]);
+    for (long j = 1; j <= 6; j++) {
+      dst[i * 12 + j * 2] = dst[i * 12 + j * 2 + 1] = x0 + (x1 - x0) * j / 6.0;
+    }
+  }
+}

FragmentedRecordWriter/FragmentedVideoWriter.swift

@@ -113,6 +113,10 @@ private class FragmentedVideoWriterDelegate: NSObject, AVAssetWriterDelegate {
 }
 
 public class FragmentedVideoWriter {
+  public var playlistURL: URL {
+    delegate.playlistURL
+  }
+
   private let outputDirectoryURL: URL
   private let outputFilePrefix: String
   private let frameRate: CMTimeScale

FragmentedRecordWriter/MasterPlaylistWriter.swift

@@ -0,0 +1,34 @@
+//
+//  MasterPlaylistWriter.swift
+//  FragmentedRecordWriter
+//
+//  Created by Kaito Udagawa on 2024/07/21.
+//
+
+import Foundation
+
+public struct MasterPlaylistWriter {
+
+  public init() {
+  }
+
+  public func write(
+    outputDirectoryURL: URL,
+    outputFilePrefix: String,
+    videoIndexURL: URL,
+    appAudioIndexURL: URL,
+    micAudioIndexURL: URL
+  ) throws {
+    let masterPlaylistURL = outputDirectoryURL.appending(path: "\(outputFilePrefix).m3u8")
+    let masterPlaylistContent = """
+      #EXTM3U
+      #EXT-X-STREAM-INF:BANDWIDTH=150000,CODECS="avc1.42e00a,mp4a.40.2",AUDIO="audio"
+      \(videoIndexURL.lastPathComponent)
+
+      #EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="audio",NAME="App",DEFAULT=YES,URI="\(appAudioIndexURL.lastPathComponent)"
+      #EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="audio",NAME="Mic",DEFAULT=NO,URI="\(micAudioIndexURL.lastPathComponent)"
+      """
+
+    try masterPlaylistContent.write(to: masterPlaylistURL, atomically: true, encoding: .utf8)
+  }
+}