From 38dfa553a2b9bd75cd7bcc209a4fc6165dcc0c4c Mon Sep 17 00:00:00 2001
From: Moritz Bunkus <moritz@bunkus.org>
Date: Sun, 21 Aug 2005 13:04:48 +0000
Subject: [PATCH] Disallow putting AVC/h.264 video in VfW compatibility mode.
 Can be forced with a new --engage option.

---
 src/common/hacks.cpp   |  1 +
 src/common/hacks.h     |  1 +
 src/mmg/mmg.cpp        |  3 +++
 src/output/p_video.cpp | 36 ++++++++++++++++++++++++++++++++++++
 4 files changed, 41 insertions(+)

diff --git a/src/common/hacks.cpp b/src/common/hacks.cpp
index 0a373ac37..5200aca1d 100644
--- a/src/common/hacks.cpp
+++ b/src/common/hacks.cpp
@@ -38,6 +38,7 @@ static const char *mosu_hacks[] = {
   ENGAGE_FORCE_PASSTHROUGH_PACKETIZER,
   ENGAGE_AVC_USE_BFRAMES,
   ENGAGE_WRITE_HEADERS_TWICE,
+  ENGAGE_ALLOW_AVC_IN_VFW_MODE,
   NULL
 };
 static vector<string> engaged_hacks;
diff --git a/src/common/hacks.h b/src/common/hacks.h
index 89f47a6fc..5dbe2b091 100644
--- a/src/common/hacks.h
+++ b/src/common/hacks.h
@@ -35,6 +35,7 @@ using namespace std;
 #define ENGAGE_FORCE_PASSTHROUGH_PACKETIZER "force_passthrough_packetizer"
 #define ENGAGE_AVC_USE_BFRAMES "avc_use_bframes"
 #define ENGAGE_WRITE_HEADERS_TWICE "write_headers_twice"
+#define ENGAGE_ALLOW_AVC_IN_VFW_MODE "allow_avc_in_vfw_mode"
 
 void MTX_DLL_API engage_hacks(const string &hacks);
 bool MTX_DLL_API hack_engaged(const string &hack);
diff --git a/src/mmg/mmg.cpp b/src/mmg/mmg.cpp
index 2624ff938..d97685693 100644
--- a/src/mmg/mmg.cpp
+++ b/src/mmg/mmg.cpp
@@ -131,6 +131,9 @@ wxString cli_options[][2] = {
   { wxT("--engage force_passthrough_packetizer"),
     wxT("Forces the Matroska reader to use the generic passthrough "
         "packetizer even for known and supported track types.") },
+  { wxT("--engage allow_avc_in_vfw_mode"),
+    wxT("Allows storing AVC/h.264 video in Video-for-Windows compatibility "
+        "mode, e.g. when it is read from an AVI") },
   { wxT("--engage cow"),
     wxT("No help available.") },
   { wxT(""), wxT("") }
diff --git a/src/output/p_video.cpp b/src/output/p_video.cpp
index 1959605d6..07b7b960c 100644
--- a/src/output/p_video.cpp
+++ b/src/output/p_video.cpp
@@ -66,6 +66,42 @@ video_packetizer_c::check_fourcc() {
            ti.fourcc, 4);
     set_codec_private(ti.private_data, ti.private_size);
   }
+
+  if (!hack_engaged(ENGAGE_ALLOW_AVC_IN_VFW_MODE) &&
+      (hcodec_id == MKV_V_MSCOMP) &&
+      (ti.private_data != NULL) &&
+      (ti.private_size >= sizeof(alBITMAPINFOHEADER))) {
+    const char *avc_fourccs[] = {
+      "h264", "x264", "avc1", NULL
+    };
+    const char *fourcc;
+    int i;
+
+    fourcc = (const char *)
+      &((alBITMAPINFOHEADER *)ti.private_data)->bi_compression;
+    for (i = 0; NULL != avc_fourccs[i]; ++i)
+      if (!strncasecmp(fourcc, avc_fourccs[i], 4))
+        mxerror(FMT_TID "You are trying to put AVC/h.264 video from an AVI "
+                "or a similar VfW (Video for Windows) compatible source into "
+                "a Matroska file in the so-called 'VfW compatibility mode'. "
+                "Please note that this is not the official way to store "
+                "AVC/h.264 video in Matroska. Therefore proper playback of "
+                "such files cannot be guaranteed, and we strongly urge you "
+                "not to continue to do this.\n"
+                "At the moment mkvmerge does not support converting from "
+                "VfW-mode AVC/h.264 tracks to native Matroska-mode AVC/h.264 "
+                "tracks. You can, however, first import the video track "
+                "into a MP4 file with e.g. 'MP4Box' (use Google). Then "
+                "you can use mkvmerge and put the video into a Matroska "
+                "file.\n"
+                "If you really know what you are doing then you can force "
+                "mkvmerge to put this AVC/h.264 track into a Matroska file "
+                "even in VfW mode if you add '--engage allow_avc_in_vfw_mode' "
+                "to the command line. You can do that in mmg with the "
+                "'Add command line options' menu entry in the 'Muxing' "
+                "menu.\n",
+                ti.fname.c_str(), (int64_t)ti.id);
+  }
 }
 
 void