Merge 2867b6c into c00a14f

gexgd0419 · web-flow · commit 785946df6890 · 2025-02-14T14:11:38.000Z
diff --git a/nvdaHelper/local/wasapi.cpp b/nvdaHelper/local/wasapi.cpp
@@ -346,16 +346,24 @@ HRESULT WasapiPlayer::feed(unsigned char* data, unsigned int size,
 		return true;
 	};
 
+	bool shouldInsertSilentFrame = false;
 	if (isTrimmingLeadingSilence) {
-		size_t silenceSize = SilenceDetect::getLeadingSilenceSize(&format, data, size);
+		// If data is null, treat the whole chunk as silence.
+		size_t silenceSize = data ? SilenceDetect::getLeadingSilenceSize(&format, data, size) : size;
 		if (silenceSize >= size) {
 			// The whole chunk is silence. Continue checking for silence in the next chunk.
 			remainingFrames = 0;
 		} else {
 			// Silence ends in this chunk. Skip the silence and continue.
 			data += silenceSize;
-			remainingFrames = (size - silenceSize) / format.nBlockAlign;
+			size -= silenceSize;
+			remainingFrames = size / format.nBlockAlign;
 			isTrimmingLeadingSilence = false;  // Stop checking for silence
+
+			// Signals to insert one silent frame before the trimmed audio in this chunk.
+			// Not doing so may cause the beginning of the audio to be chopped off.
+			// See: https://github.com/nvaccess/nvda/discussions/17697
+			shouldInsertSilentFrame = true;
 		}
 	}
 
@@ -407,14 +415,30 @@ HRESULT WasapiPlayer::feed(unsigned char* data, unsigned int size,
 			}
 		}
 		// We might have more frames than will fit in the buffer. Send what we can.
+		// If we need to insert a silent frame, the frame counts towards the total frame count,
+		// but does not count towards the total byte count, as it's not in the provided data buffer.
+		if (shouldInsertSilentFrame) {
+			remainingFrames++;
+		}
 		const UINT32 sendFrames = std::min(remainingFrames,
 			bufferFrames - paddingFrames);
-		const UINT32 sendBytes = sendFrames * format.nBlockAlign;
+		const UINT32 sendBytes = (sendFrames - (shouldInsertSilentFrame ? 1 : 0))
+			* format.nBlockAlign;
 		BYTE* buffer;
 		hr = render->GetBuffer(sendFrames, &buffer);
 		if (FAILED(hr)) {
 			return hr;
 		}
+		if (shouldInsertSilentFrame) {
+			// If needed, insert one frame of silence at the beginning
+			if (format.wFormatTag == WAVE_FORMAT_PCM && format.wBitsPerSample == 8) {
+				memset(buffer, 0x80, format.nBlockAlign);
+			} else {
+				memset(buffer, 0, format.nBlockAlign);
+			}
+			buffer += format.nBlockAlign;
+			shouldInsertSilentFrame = false;
+		}
 		if (data) {
 			memcpy(buffer, data, sendBytes);
 			hr = render->ReleaseBuffer(sendFrames, 0);
diff --git a/source/nvwave.py b/source/nvwave.py
@@ -497,7 +497,8 @@ def _idleCheck(cls):
 			if player._lastActiveTime <= threshold:
 				try:
 					NVDAHelper.localLib.wasPlay_idle(player._player)
-					player.startTrimmingLeadingSilence()
+					if player._enableTrimmingLeadingSilence:
+						player.startTrimmingLeadingSilence()
 				except OSError:
 					# #16125: IAudioClock::GetPosition sometimes fails with an access
 					# violation on a device which has been invalidated. This shouldn't happen
