diff --git a/include/libg1m.h b/include/libg1m.h
index d3c47d4..89f99a6 100644
--- a/include/libg1m.h
+++ b/include/libg1m.h
@@ -154,9 +154,11 @@ extern int g1m_mcs_insert(g1m_t *handle, g1m_mcsfile_t **tofile,
 /* ************************************************************************** */
 /* Version decoding/encoding */
 extern int g1m_decode_version(const char *raw, g1m_version_t *version);
+extern int g1m_encode_version(const g1m_version_t *version, char *raw);
 
 /* Date decoding/encoding */
 extern int g1m_decode_date(const char *raw, time_t *date);
+extern int g1m_encode_date(const time_t *date, char *raw);
 
 # ifdef __cplusplus
 }
diff --git a/include/libg1m/internals.h b/include/libg1m/internals.h
index 7fddbc3..846e8f1 100644
--- a/include/libg1m/internals.h
+++ b/include/libg1m/internals.h
@@ -92,8 +92,10 @@
 	if (err) goto fail;
 
 /* write */
-# define WRITE(BUF, SZ) \
-	(*buffer->write)(buffer->cookie, (unsigned char*)(BUF), (SZ));
+# define WRITE(BUF, SZ) { \
+	int WRITE_err = (*buffer->write)(buffer->cookie, \
+		(unsigned char*)(BUF), (SZ)); \
+	if (WRITE_err) return (WRITE_err); }
 # define DWRITE(S) WRITE(&(S), sizeof(S))
 /* ************************************************************************** */
 /*  Decoding functions                                                        */
@@ -172,6 +174,14 @@ G1M_CASHFUNC(program)
 G1M_CASFUNC(matrix)
 G1M_CASFUNC(capture)
 /* ************************************************************************** */
+/*  Handle encoding functions                                                 */
+/* ************************************************************************** */
+# define G1M_ENCFUNC(NAME) \
+extern int g1m_announce_##NAME(g1m_t *handle, size_t *size); \
+extern int g1m_encode_##NAME(g1m_t *handle, g1m_buffer_t *buffer);
+
+G1M_ENCFUNC(addin)
+/* ************************************************************************** */
 /*  Picture utilities                                                         */
 /* ************************************************************************** */
 # define alloc_pixels(W, H) \
diff --git a/include/libg1m/picture.h b/include/libg1m/picture.h
index 58ecc59..9f9afa9 100644
--- a/include/libg1m/picture.h
+++ b/include/libg1m/picture.h
@@ -25,6 +25,7 @@ extern "C" {
 /* picture format */
 typedef int g1m_pictureformat_t;
 # define g1m_pictureformat_1bit            0x0100
+# define g1m_pictureformat_1bit_r          0x0101
 # define g1m_pictureformat_1bit_packed     0x0110
 # define g1m_pictureformat_1bit_packed_r   0x0111
 # define g1m_pictureformat_1bit_packed_old 0x0120
diff --git a/src/decode/std/addin.c b/src/decode/std/addin.c
index e37cea2..64a4140 100644
--- a/src/decode/std/addin.c
+++ b/src/decode/std/addin.c
@@ -65,9 +65,9 @@ int g1m_decode_std_addin(g1m_t **h, g1m_buffer_t *buffer,
 	log_info("creation date is: %.24s", ctime(&handle->creation_date));
 
 	/* fill icon */
-	g1m_decode_picture(handle->icon_unsel, g1m_pictureformat_1bit_packed,
+	g1m_decode_picture(handle->icon_unsel, g1m_pictureformat_1bit,
 		hd.icon, handle->width, handle->height);
-	g1m_decode_picture(handle->icon_sel, g1m_pictureformat_1bit_packed_r,
+	g1m_decode_picture(handle->icon_sel, g1m_pictureformat_1bit_r,
 		hd.icon, handle->width, handle->height);
 
 	/* read content */
diff --git a/src/encode/addin.c b/src/encode/addin.c
new file mode 100644
index 0000000..797994b
--- /dev/null
+++ b/src/encode/addin.c
@@ -0,0 +1,82 @@
+/* *****************************************************************************
+ * encode/addin.c -- encode an addin.
+ * Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
+ *
+ * This file is part of libg1m.
+ * libg1m is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 3.0 of the License,
+ * or (at your option) any later version.
+ *
+ * libg1m is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with libg1m; if not, see <http://www.gnu.org/licenses/>.
+ * ************************************************************************** */
+#include <libg1m/internals.h>
+
+/**
+ *	g1m_announce_addin:
+ *	Announce an add-in's size.
+ *
+ *	@arg	handle		the handle.
+ *	@arg	size		the size to feed.
+ *	@return				the error code (0 if ok).
+ */
+
+int g1m_announce_addin(g1m_t *handle, size_t *size)
+{
+	*size += sizeof(struct standard_header) + sizeof(struct g1a_subheader);
+	*size += handle->size;
+	return (0);
+}
+
+/**
+ *	g1m_encode_addin:
+ *	Encode an add-in.
+ *
+ *	@arg	handle		the handle.
+ *	@arg	buffer		the buffer to which to write to.
+ *	@return				the error code (0 if ok).
+ */
+
+int g1m_encode_addin(g1m_t *handle, g1m_buffer_t *buffer)
+{
+	/* make the StandardHeader up */
+	size_t filesize; g1m_announce_addin(handle, &filesize);
+	struct standard_header std = {
+		.main_id = "USBPower",
+		.subtype = "\xF3\x00\x10\x00\x10\x00",
+		.filesize = htobe32((uint32_t)filesize),
+		.control = (filesize + 0x41) & 0xFF,
+		.control2 = (filesize + 0xB8) & 0xFF,
+		.number = 0xFFFF};
+
+	/* reverse it and output it */
+	uint8_t *b = (void*)&std;
+	for (size_t i = 0; i < sizeof(struct standard_header); i++) b[i] = ~b[i];
+	DWRITE(std)
+
+	/* make the add-in subheader up and output it */
+	filesize -= sizeof(struct standard_header);
+	struct g1a_subheader sub = {
+		.estrips_count = 0,
+		.filesize = htobe32(filesize)};
+	strncpy((char*)sub.title, handle->title, 8);
+	strncpy((char*)sub.internal_name, handle->intname, 8);
+	g1m_encode_version(&handle->version, (char*)sub.version);
+	g1m_encode_date(&handle->creation_date, (char*)sub.creation_date);
+	g1m_encode_picture((const uint32_t**)handle->icon_unsel,
+		g1m_pictureformat_1bit, sub.icon,
+		G1A_ICON_WIDTH, G1A_ICON_HEIGHT);
+	DWRITE(sub)
+
+	/* output the content */
+	WRITE(handle->content, handle->size)
+
+	/* no error! */
+	return (0);
+}
diff --git a/src/encode/main.c b/src/encode/main.c
index 12052aa..11cc0f2 100644
--- a/src/encode/main.c
+++ b/src/encode/main.c
@@ -17,8 +17,7 @@
  * along with libg1m; if not, see <http://www.gnu.org/licenses/>.
  * ************************************************************************** */
 #include <libg1m/internals.h>
-#define A(NAME) g1m_announce_##NAME
-#define E(NAME) g1m_encode_##NAME
+#define FUNCS(NAME) g1m_announce_##NAME, g1m_encode_##NAME
 
 /* ************************************************************************** */
 /*  Correspondances                                                           */
@@ -38,6 +37,9 @@ struct corresp {
 
 /* All correspondances */
 static const struct corresp encodings[] = {
+	/* add-in types */
+	{g1m_type_addin, g1m_platform_fx, FUNCS(addin)},
+
 	/* sentinel */
 	{0, 0, NULL, NULL}
 };
@@ -71,7 +73,7 @@ int g1m_encode(g1m_t *handle, g1m_buffer_t *buffer)
 
 	/* announce, if necessary */
 	if (buffer->announce) {
-		size_t size;
+		size_t size = 0;
 		if ((err = (*c->announce)(handle, &size))
 		 || (err = (*buffer->announce)(buffer->cookie, size)))
 			return (err);
diff --git a/src/manage/handle.c b/src/manage/handle.c
index 51ead67..fb249f9 100644
--- a/src/manage/handle.c
+++ b/src/manage/handle.c
@@ -231,6 +231,8 @@ int g1m_make_addin(g1m_t **h, g1m_platform_t platform, size_t size,
 	if (!handle->icon_sel) goto fail;
 
 	/* prepare pictures */
+	handle->width = width;
+	handle->height = height;
 	prepare_pixels(handle->icon_unsel, width, height)
 	prepare_pixels(handle->icon_sel, width, height)
 
diff --git a/src/utils/date.c b/src/utils/date.c
index 459e775..a5971b2 100644
--- a/src/utils/date.c
+++ b/src/utils/date.c
@@ -48,3 +48,23 @@ int g1m_decode_date(const char *c, time_t *t)
 	*t = mktime(&date);
 	return (0);
 }
+
+/**
+ *	g1m_encode_date:
+ *	Encode a date from a string.
+ *
+ *	@arg	t		the source timestamp.
+ *	@arg	c		the destination string.
+ *	@return			the error code (0 if ok).
+ */
+
+int g1m_encode_date(const time_t *t, char *c)
+{
+	/* helper values */
+	struct tm *date = gmtime(t);
+	char buf[15]; sprintf(buf, "%04u.%02u%02u.%02u%02u",
+		min(date->tm_year + 1900, 9999), date->tm_mon + 1, date->tm_mday,
+		date->tm_hour, date->tm_min);
+	memcpy(c, buf, 14);
+	return (0);
+}
diff --git a/src/utils/picture.c b/src/utils/picture.c
index 60fe2ae..b4b4e4f 100644
--- a/src/utils/picture.c
+++ b/src/utils/picture.c
@@ -58,6 +58,36 @@ int g1m_decode_picture(uint32_t **pixels, g1m_pictureformat_t format,
 	int msk; const unsigned char *o, *g, *b, *r2; size_t off;
 
 	switch (format) {
+	case g1m_pictureformat_1bit:
+		for (unsigned int y = 0; y < height; y++) {
+			msk = 0x80;
+			for (unsigned int x = 0; x < width; x++) {
+				/* get pixel */
+				pixels[y][x] = (*raw & msk) ? 0x000000 : 0xFFFFFF;
+
+				/* go to next */
+				raw += msk & 1;
+				msk = (msk >> 1) | ((msk & 1) << 7);
+			}
+			if (width & 0x7) raw++;
+		}
+		break;
+
+	case g1m_pictureformat_1bit_r:
+		for (unsigned int y = 0; y < height; y++) {
+			msk = 0x80;
+			for (unsigned int x = 0; x < width; x++) {
+				/* get pixel */
+				pixels[y][x] = (*raw & msk) ? 0xFFFFFF : 0x000000;
+
+				/* go to next */
+				raw += msk & 1;
+				msk = (msk >> 1) | ((msk & 1) << 7);
+			}
+			if (width & 0x7) raw++;
+		}
+		break;
+
 	case g1m_pictureformat_4bit_mono:
 		raw = &raw[(height * width / 2) * 2];
 	case g1m_pictureformat_1bit_packed:
@@ -214,6 +244,38 @@ int g1m_encode_picture(const uint32_t **pixels, g1m_pictureformat_t format,
 	int msk;
 
 	switch (format) {
+	case g1m_pictureformat_1bit:
+		memset(raw, 0, g1m_picturesize_1bit(width, height));
+		for (unsigned int y = 0; y < height; y++) {
+			msk = 0x80;
+			for (unsigned int x = 0; x < width; x++) {
+				/* get pixel */
+				if (!pixels[y][x]) *raw |= msk;
+
+				/* go to next */
+				raw += msk & 1;
+				msk = (msk >> 1) | ((msk & 1) << 7);
+			}
+			if (width & 0x7) raw++;
+		}
+		break;
+
+	case g1m_pictureformat_1bit_r:
+		memset(raw, 0, g1m_picturesize_1bit(width, height));
+		for (unsigned int y = 0; y < height; y++) {
+			msk = 0x80;
+			for (unsigned int x = 0; x < width; x++) {
+				/* get pixel */
+				if (pixels[y][x]) *raw |= msk;
+
+				/* go to next */
+				raw += msk & 1;
+				msk = (msk >> 1) | ((msk & 1) << 7);
+			}
+			if (width & 0x7) raw++;
+		}
+		break;
+
 	case g1m_pictureformat_1bit_packed:
 		msk = 0x80;
 		for (unsigned int y = 0; y < height; y++)
diff --git a/src/utils/version.c b/src/utils/version.c
index 883738d..ed5ea1b 100644
--- a/src/utils/version.c
+++ b/src/utils/version.c
@@ -45,3 +45,20 @@ int g1m_decode_version(const char *raw, g1m_version_t *version)
 	/* no error */
 	return (0);
 }
+
+/**
+ *	g1m_encode_version:
+ *	Encode a version into an 'MM.mm.ffff' formatted version string.
+ *
+ *	@arg	version	the version to encode.
+ *	@arg	the string to encode into.
+ *	@return			the error code (if any).
+ */
+
+int g1m_encode_version(const g1m_version_t *version, char *raw)
+{
+	char buf[11]; sprintf(buf, "%02u.%02u.%04u",
+		version->major, version->minor, version->revision);
+	memcpy(raw, buf, 10);
+	return (0);
+}