From cdd14732adf61aacbf7e6f15db215b8881b3ea10 Mon Sep 17 00:00:00 2001
From: Georgi Kostov <p_e_a@gbg.bg>
Date: Sun, 9 Nov 2025 11:53:53 +0200
Subject: [PATCH] Send the initial boundary line before the first part in the
 response (to conform with the RFC and appease ffmpeg)

refs #67
---
 src/esp32cam/asyncweb.cpp | 3 ++-
 src/esp32cam/asyncweb.hpp | 2 ++
 src/esp32cam/mjpeg.cpp    | 5 +++--
 src/esp32cam/mjpeg.hpp    | 2 +-
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/esp32cam/asyncweb.cpp b/src/esp32cam/asyncweb.cpp
index c4b1f1e..b2e7d15 100644
--- a/src/esp32cam/asyncweb.cpp
+++ b/src/esp32cam/asyncweb.cpp
@@ -192,7 +192,8 @@ MjpegResponse::sendPart(uint8_t* buf, size_t buflen) {
   if (m_sendRemain == 0) {
     switch (m_sendNext) {
       case SIPartHeader:
-        m_hdr.preparePartHeader(m_ctrl.getFrame()->size());
+        m_hdr.preparePartHeader(m_ctrl.getFrame()->size(), !isInitialBoundarySent);
+        isInitialBoundarySent = true;
         m_sendBuf = reinterpret_cast<const uint8_t*>(m_hdr.buf);
         m_sendRemain = m_hdr.size;
         m_sendNext = SIFrame;
diff --git a/src/esp32cam/asyncweb.hpp b/src/esp32cam/asyncweb.hpp
index e697c9b..df36430 100644
--- a/src/esp32cam/asyncweb.hpp
+++ b/src/esp32cam/asyncweb.hpp
@@ -104,6 +104,8 @@ class MjpegResponse : public AsyncAbstractResponse {
 private:
   size_t sendPart(uint8_t* buf, size_t buflen);
 
+  bool isInitialBoundarySent = false;
+
 private:
   detail::CaptureTask m_task;
   using Ctrl = detail::MjpegController;
diff --git a/src/esp32cam/mjpeg.cpp b/src/esp32cam/mjpeg.cpp
index ef99ef9..9471238 100644
--- a/src/esp32cam/mjpeg.cpp
+++ b/src/esp32cam/mjpeg.cpp
@@ -77,8 +77,9 @@ MjpegHeader::prepareResponseContentType() {
 }
 
 void
-MjpegHeader::preparePartHeader(size_t contentLength) {
-  size = snprintf(buf, sizeof(buf),
+MjpegHeader::preparePartHeader(size_t contentLength, bool includeInitialBoundary) {
+  size = includeInitialBoundary ? snprintf(buf, sizeof(buf), "--" BOUNDARY "\r\n") : 0;
+  size += snprintf(buf + size, sizeof(buf) - size,
                   "Content-Type: image/jpeg\r\n"
                   "Content-Length: %zu\r\n"
                   "\r\n",
diff --git a/src/esp32cam/mjpeg.hpp b/src/esp32cam/mjpeg.hpp
index b273b94..0940b1e 100644
--- a/src/esp32cam/mjpeg.hpp
+++ b/src/esp32cam/mjpeg.hpp
@@ -108,7 +108,7 @@ class MjpegHeader {
 
   void prepareResponseContentType();
 
-  void preparePartHeader(size_t contentLength);
+  void preparePartHeader(size_t contentLength, bool includeInitialBoundary = false);
 
   void preparePartTrailer();