diff --git a/client/CFFmpegH264Encoder.cpp b/client/CFFmpegH264Encoder.cpp
index e802d76..dceeb9e 100644
--- a/client/CFFmpegH264Encoder.cpp
+++ b/client/CFFmpegH264Encoder.cpp
@@ -210,9 +210,10 @@ int CFFmpegH264Encoder::convertRGB24ToNV12(uint8_t* rgb, uint32_t stride,
                                            uint32_t width, uint32_t height,
                                            int direction)
 {
-    int signed_height = direction * (int)height;
-    int w = (int)width;
-    int h = (int)height;
+    // Clamp to encoder's even-aligned frame dimensions (same reason as encode()).
+    int w = m_ctx->width;
+    int h = m_ctx->height;
+    int signed_height = direction * h;
     int y_size  = w * h;
     int uv_size = (w / 2) * (h / 2);
     m_i420Scratch.resize(y_size + 2 * uv_size);
@@ -249,8 +250,12 @@ int CFFmpegH264Encoder::encode(
     if (!m_ctx || !m_frame || !m_packet) return -1;
     if (av_frame_make_writable(m_frame) < 0) return -1;
 
-    int w = (int)width;
-    int h = (int)height;
+    // Use the encoder's even-aligned dimensions, not the raw passed-in values.
+    // m_ctx->width/height = p.width & ~1, m_frame is allocated for exactly those
+    // dimensions. If we pass an odd width/height, ARGBToNV12 writes one extra row
+    // past the end of m_frame->data[0] → heap corruption / access violation.
+    int w = m_ctx->width;
+    int h = m_ctx->height;
     int signed_height = direction * h;
 
     if (bpp == 32) {