Front End Streaming Playback Improvements

2025-09-13 15:22:26 -04:00
parent cdeb300d5e
commit 0fa8ac7379
8 changed files with 417 additions and 11 deletions
@@ -0,0 +1,118 @@
+interface WavHeader {
+    sampleRate: number;
+    channels: number;
+    bitsPerSample: number;
+    byteRate: number;
+    blockAlign: number;
+    dataSize: number;
+    headerSize: number;
+}
+
+class WavUtils {
+    static parseHeader(chunks: Uint8Array[], totalSize: number): WavHeader | null {
+        if (totalSize < 44) return null;
+
+        const concatenated = new Uint8Array(totalSize);
+        let offset = 0;
+        for (const chunk of chunks) {
+            concatenated.set(chunk, offset);
+            offset += chunk.length;
+        }
+
+        const view = new DataView(concatenated.buffer, 0, 44);
+        
+        // Check RIFF header
+        const riff = new TextDecoder().decode(concatenated.slice(0, 4));
+        if (riff !== 'RIFF') return null;
+
+        const wave = new TextDecoder().decode(concatenated.slice(8, 12));
+        if (wave !== 'WAVE') return null;
+
+        // Find fmt chunk
+        let fmtOffset = 12;
+        while (fmtOffset < totalSize - 8) {
+            const chunkId = new TextDecoder().decode(concatenated.slice(fmtOffset, fmtOffset + 4));
+            const chunkSize = view.getUint32(fmtOffset + 4, true);
+            
+            if (chunkId === 'fmt ') {
+                const channels = view.getUint16(fmtOffset + 10, true);
+                const sampleRate = view.getUint32(fmtOffset + 12, true);
+                const byteRate = view.getUint32(fmtOffset + 16, true);
+                const blockAlign = view.getUint16(fmtOffset + 20, true);
+                const bitsPerSample = view.getUint16(fmtOffset + 22, true);
+                
+                return {
+                    sampleRate,
+                    channels,
+                    bitsPerSample,
+                    byteRate,
+                    blockAlign,
+                    dataSize: 0, // Will be updated when we find data chunk
+                    headerSize: 44
+                };
+            }
+            
+            fmtOffset += 8 + chunkSize;
+        }
+
+        return null;
+    }
+
+    static createHeader(wavHeader: WavHeader, dataSize: number): Uint8Array {
+        const header = new ArrayBuffer(44);
+        const view = new DataView(header);
+        
+        // RIFF header
+        view.setUint8(0, 0x52); view.setUint8(1, 0x49); view.setUint8(2, 0x46); view.setUint8(3, 0x46); // "RIFF"
+        view.setUint32(4, 36 + dataSize, true); // File size
+        view.setUint8(8, 0x57); view.setUint8(9, 0x41); view.setUint8(10, 0x56); view.setUint8(11, 0x45); // "WAVE"
+        
+        // fmt chunk
+        view.setUint8(12, 0x66); view.setUint8(13, 0x6d); view.setUint8(14, 0x74); view.setUint8(15, 0x20); // "fmt "
+        view.setUint32(16, 16, true); // fmt chunk size
+        view.setUint16(20, 1, true); // Audio format (PCM)
+        view.setUint16(22, wavHeader.channels, true);
+        view.setUint32(24, wavHeader.sampleRate, true);
+        view.setUint32(28, wavHeader.byteRate, true);
+        view.setUint16(32, wavHeader.blockAlign, true);
+        view.setUint16(34, wavHeader.bitsPerSample, true);
+        
+        // data chunk header
+        view.setUint8(36, 0x64); view.setUint8(37, 0x61); view.setUint8(38, 0x74); view.setUint8(39, 0x61); // "data"
+        view.setUint32(40, dataSize, true);
+        
+        return new Uint8Array(header);
+    }
+
+    static extractAudioData(chunks: Uint8Array[], totalSize: number, headerSize: number, chunkSize: number): Uint8Array {
+        const bufferData = new Uint8Array(chunkSize + headerSize);
+        let dataOffset = headerSize; // Skip header space initially
+        let remainingSize = chunkSize;
+        
+        // Fill with audio data, skipping the header from the first chunk
+        let chunkIndex = 0;
+        let chunkOffset = headerSize; // Skip WAV header in first chunk
+        
+        while (remainingSize > 0 && chunkIndex < chunks.length) {
+            const chunk = chunks[chunkIndex];
+            const availableInChunk = chunk.length - chunkOffset;
+            const toCopy = Math.min(availableInChunk, remainingSize);
+            
+            if (toCopy > 0) {
+                bufferData.set(chunk.slice(chunkOffset, chunkOffset + toCopy), dataOffset);
+                dataOffset += toCopy;
+                remainingSize -= toCopy;
+                chunkOffset += toCopy;
+            }
+            
+            if (chunkOffset >= chunk.length) {
+                chunkIndex++;
+                chunkOffset = 0; // No header to skip in subsequent chunks
+            }
+        }
+
+        return bufferData.slice(0, dataOffset);
+    }
+}
+
+export { WavHeader, WavUtils };