Fix streaming minors: isActive_ sentinel, WAV error message, TextDecoder hoist, MIME 400, fmt first-match, processedBytes comment

DeepDrftWeb/Interop/audio/PlaybackScheduler.ts

@@ -64,7 +64,10 @@ export class PlaybackScheduler {
      * Get current playback position in seconds (includes playbackOffset for seek-beyond-buffer)
      */
     getCurrentPosition(): number {
-        if (this.playbackAnchorTime === 0) {
+        // Use isActive_ as the sentinel for "playback is running", not playbackAnchorTime == 0.
+        // AudioContext.currentTime can legitimately be 0 at context creation, so comparing
+        // against 0 would incorrectly treat an active stream started at t=0 as paused.
+        if (!this.isActive_) {
             return this.playbackAnchorPosition + this.playbackOffset;
         }
         const elapsed = this.contextManager.currentTime - this.playbackAnchorTime;
@@ -143,8 +146,11 @@ export class PlaybackScheduler {
             return; // No new buffers
         }
 
-        if (this.nextScheduleTime === 0) {
-            this.nextScheduleTime = this.contextManager.currentTime + 0.01;
+        // Use isActive_ as the sentinel for "playback is running", not nextScheduleTime === 0.
+        // AudioContext.currentTime can legitimately be 0 at context creation, which would cause
+        // nextScheduleTime === 0 to incorrectly reset a value already set by playFromPosition.
+        if (!this.isActive_) {
+            return;
         }
 
         this.scheduleBuffersFrom(this.nextBufferIndex, 0);

DeepDrftWeb/Interop/audio/StreamDecoder.ts

@@ -51,6 +51,9 @@ export class StreamDecoder {
     private contextManager: AudioContextManager;
     private wavHeader: WavHeader | null = null;
     private rawChunks: Uint8Array[] = [];
+    // totalRawBytes and processedBytes are JS number (IEEE 754 double), which can
+    // represent integers exactly up to 2^53 bytes (~8 PB). WAV files are bounded
+    // at 4 GB by the 32-bit RIFF size field, so overflow is not a practical concern.
     private totalRawBytes: number = 0;
     private processedBytes: number = 0;
     private totalStreamLength: number = 0;

DeepDrftWeb/Interop/wavutils.ts

@@ -22,11 +22,16 @@ class WavUtils {
         // Need a DataView that spans the entire buffer for chunk searching
         const view = new DataView(concatenated.buffer);
 
+        // Allocate TextDecoder once for the entire parse pass. Constructing it
+        // inside the chunk-walk loop would create a new instance per iteration,
+        // which is non-trivial and unnecessary — a single instance is reusable.
+        const decoder = new TextDecoder();
+
         // Check RIFF header
-        const riff = new TextDecoder().decode(concatenated.slice(0, 4));
+        const riff = decoder.decode(concatenated.slice(0, 4));
         if (riff !== 'RIFF') return null;
 
-        const wave = new TextDecoder().decode(concatenated.slice(8, 12));
+        const wave = decoder.decode(concatenated.slice(8, 12));
         if (wave !== 'WAVE') return null;
 
         // Variables to store parsed header info
@@ -43,7 +48,7 @@ class WavUtils {
         // Find fmt and data chunks
         let chunkOffset = 12;
         while (chunkOffset < totalSize - 8) {
-            const chunkId = new TextDecoder().decode(concatenated.slice(chunkOffset, chunkOffset + 4));
+            const chunkId = decoder.decode(concatenated.slice(chunkOffset, chunkOffset + 4));
             const chunkSize = view.getUint32(chunkOffset + 4, true);
 
             if (chunkId === 'fmt ') {