diff --git a/src/lib/crypto.cc b/src/lib/crypto.cc
index c67fc27fa..494924daa 100644
--- a/src/lib/crypto.cc
+++ b/src/lib/crypto.cc
@@ -34,39 +34,39 @@ using namespace dcpomatic;
 /** The cipher that this code uses */
 #define CIPHER EVP_aes_256_cbc()
 
-dcp::Data
+dcp::ArrayData
 dcpomatic::random_iv ()
 {
 	EVP_CIPHER const * cipher = CIPHER;
-	dcp::Data iv (EVP_CIPHER_iv_length(cipher));
-	RAND_bytes (iv.data().get(), iv.size());
+	dcp::ArrayData iv (EVP_CIPHER_iv_length(cipher));
+	RAND_bytes (iv.data(), iv.size());
 	return iv;
 }
 
-dcp::Data
-dcpomatic::encrypt (string plaintext, dcp::Data key, dcp::Data iv)
+dcp::ArrayData
+dcpomatic::encrypt (string plaintext, dcp::ArrayData key, dcp::ArrayData iv)
 {
 	EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new ();
 	if (!ctx) {
 		throw CryptoError ("could not create cipher context");
 	}
 
-	int r = EVP_EncryptInit_ex (ctx, CIPHER, 0, key.data().get(), iv.data().get());
+	int r = EVP_EncryptInit_ex (ctx, CIPHER, 0, key.data(), iv.data());
 	if (r != 1) {
 		throw CryptoError ("could not initialise cipher context for encryption");
 	}
 
-	dcp::Data ciphertext (plaintext.size() * 2);
+	dcp::ArrayData ciphertext (plaintext.size() * 2);
 
 	int len;
-	r = EVP_EncryptUpdate (ctx, ciphertext.data().get(), &len, (uint8_t const *) plaintext.c_str(), plaintext.size());
+	r = EVP_EncryptUpdate (ctx, ciphertext.data(), &len, (uint8_t const *) plaintext.c_str(), plaintext.size());
 	if (r != 1) {
 		throw CryptoError ("could not encrypt data");
 	}
 
 	int ciphertext_len = len;
 
-	r = EVP_EncryptFinal_ex (ctx, ciphertext.data().get() + len, &len);
+	r = EVP_EncryptFinal_ex (ctx, ciphertext.data() + len, &len);
 	if (r != 1) {
 		throw CryptoError ("could not finish encryption");
 	}
@@ -79,40 +79,40 @@ dcpomatic::encrypt (string plaintext, dcp::Data key, dcp::Data iv)
 }
 
 string
-dcpomatic::decrypt (dcp::Data ciphertext, dcp::Data key, dcp::Data iv)
+dcpomatic::decrypt (dcp::ArrayData ciphertext, dcp::ArrayData key, dcp::ArrayData iv)
 {
 	EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new ();
 	if (!ctx) {
 		throw CryptoError ("could not create cipher context");
 	}
 
-	int r = EVP_DecryptInit_ex (ctx, CIPHER, 0, key.data().get(), iv.data().get());
+	int r = EVP_DecryptInit_ex (ctx, CIPHER, 0, key.data(), iv.data());
 	if (r != 1) {
 		throw CryptoError ("could not initialise cipher context for decryption");
 	}
 
-	dcp::Data plaintext (ciphertext.size() * 2);
+	dcp::ArrayData plaintext (ciphertext.size() * 2);
 
 	int len;
-	r = EVP_DecryptUpdate (ctx, plaintext.data().get(), &len, ciphertext.data().get(), ciphertext.size());
+	r = EVP_DecryptUpdate (ctx, plaintext.data(), &len, ciphertext.data(), ciphertext.size());
 	if (r != 1) {
 		throw CryptoError ("could not decrypt data");
 	}
 
 	int plaintext_len = len;
 
-	r = EVP_DecryptFinal_ex (ctx, plaintext.data().get() + len, &len);
+	r = EVP_DecryptFinal_ex (ctx, plaintext.data() + len, &len);
 	if (r != 1) {
 		throw CryptoError ("could not finish decryption");
 	}
 
 	plaintext_len += len;
 	plaintext.set_size (plaintext_len + 1);
-	plaintext.data().get()[plaintext_len] = '\0';
+	plaintext.data()[plaintext_len] = '\0';
 
 	EVP_CIPHER_CTX_free (ctx);
 
-	return string ((char *) plaintext.data().get());
+	return string ((char *) plaintext.data());
 }
 
 int
diff --git a/src/lib/crypto.h b/src/lib/crypto.h
index e450d4db1..ee0ff9b55 100644
--- a/src/lib/crypto.h
+++ b/src/lib/crypto.h
@@ -18,14 +18,14 @@
 
 */
 
-#include <dcp/data.h>
+#include <dcp/array_data.h>
 
 namespace dcpomatic {
-	
-dcp::Data random_iv ();
-dcp::Data encrypt (std::string plaintext, dcp::Data key, dcp::Data iv);
-std::string decrypt (dcp::Data ciphertext, dcp::Data key, dcp::Data iv);
-int crypto_key_length ();	
+
+dcp::ArrayData random_iv ();
+dcp::ArrayData encrypt (std::string plaintext, dcp::ArrayData key, dcp::ArrayData iv);
+std::string decrypt (dcp::ArrayData ciphertext, dcp::ArrayData key, dcp::ArrayData iv);
+int crypto_key_length ();
 
 }
 
diff --git a/src/lib/dcp_video.cc b/src/lib/dcp_video.cc
index 36928b3fc..b3461e569 100644
--- a/src/lib/dcp_video.cc
+++ b/src/lib/dcp_video.cc
@@ -60,7 +60,7 @@ using std::string;
 using std::cout;
 using boost::shared_ptr;
 using dcp::Size;
-using dcp::Data;
+using dcp::ArrayData;
 using dcp::raw_convert;
 #if BOOST_VERSION >= 106100
 using namespace boost::placeholders;
@@ -118,12 +118,12 @@ DCPVideo::convert_to_xyz (shared_ptr<const PlayerVideo> frame, dcp::NoteHandler
 /** J2K-encode this frame on the local host.
  *  @return Encoded data.
  */
-Data
+ArrayData
 DCPVideo::encode_locally ()
 {
 	string const comment = Config::instance()->dcp_j2k_comment();
 
-	Data enc = dcp::compress_j2k (
+	ArrayData enc = dcp::compress_j2k (
 		convert_to_xyz (_frame, boost::bind(&Log::dcp_log, dcpomatic_log.get(), _1, _2)),
 		_j2k_bandwidth,
 		_frames_per_second,
@@ -154,7 +154,7 @@ DCPVideo::encode_locally ()
  *  @param timeout timeout in seconds.
  *  @return Encoded data.
  */
-Data
+ArrayData
 DCPVideo::encode_remotely (EncodeServerDescription serv, int timeout)
 {
 	boost::asio::io_service io_service;
@@ -192,9 +192,9 @@ DCPVideo::encode_remotely (EncodeServerDescription serv, int timeout)
 	*/
 	Socket::ReadDigestScope ds (socket);
 	LOG_TIMING("start-remote-encode thread=%1", thread_id ());
-	Data e (socket->read_uint32 ());
+	ArrayData e (socket->read_uint32 ());
 	LOG_TIMING("start-remote-receive thread=%1", thread_id ());
-	socket->read (e.data().get(), e.size());
+	socket->read (e.data(), e.size());
 	LOG_TIMING("finish-remote-receive thread=%1", thread_id ());
 	if (!ds.check()) {
 		throw NetworkError ("Checksums do not match");
diff --git a/src/lib/dcp_video.h b/src/lib/dcp_video.h
index 81ddc4470..aa11d7d3c 100644
--- a/src/lib/dcp_video.h
+++ b/src/lib/dcp_video.h
@@ -21,7 +21,7 @@
 #include "types.h"
 #include "encode_server_description.h"
 #include <libcxml/cxml.h>
-#include <dcp/data.h>
+#include <dcp/array_data.h>
 
 /** @file  src/dcp_video_frame.h
  *  @brief A single frame of video destined for a DCP.
@@ -45,8 +45,8 @@ public:
 	DCPVideo (boost::shared_ptr<const PlayerVideo>, int, int, int, Resolution);
 	DCPVideo (boost::shared_ptr<const PlayerVideo>, cxml::ConstNodePtr);
 
-	dcp::Data encode_locally ();
-	dcp::Data encode_remotely (EncodeServerDescription, int timeout = 30);
+	dcp::ArrayData encode_locally ();
+	dcp::ArrayData encode_remotely (EncodeServerDescription, int timeout = 30);
 
 	int index () const {
 		return _index;
diff --git a/src/lib/emailer.cc b/src/lib/emailer.cc
index dc216e90c..6fe537eb1 100644
--- a/src/lib/emailer.cc
+++ b/src/lib/emailer.cc
@@ -35,7 +35,7 @@ using std::list;
 using std::cout;
 using std::pair;
 using boost::shared_ptr;
-using dcp::Data;
+using dcp::ArrayData;
 
 Emailer::Emailer (string from, list<string> to, string subject, string body)
 	: _from (from)
@@ -155,8 +155,8 @@ Emailer::send (string server, int port, EmailProtocol protocol, string user, str
 		BIO* bio = BIO_new (BIO_s_mem());
 		bio = BIO_push (b64, bio);
 
-		Data data (i.file);
-		BIO_write (bio, data.data().get(), data.size());
+		ArrayData data (i.file);
+		BIO_write (bio, data.data(), data.size());
 		(void) BIO_flush (bio);
 
 		char* out;
diff --git a/src/lib/encode_server.cc b/src/lib/encode_server.cc
index f4224798b..9e096fdfa 100644
--- a/src/lib/encode_server.cc
+++ b/src/lib/encode_server.cc
@@ -65,8 +65,8 @@ using boost::thread;
 using boost::bind;
 using boost::scoped_array;
 using boost::optional;
+using dcp::ArrayData;
 using dcp::Size;
-using dcp::Data;
 using dcp::raw_convert;
 
 EncodeServer::EncodeServer (bool verbose, int num_threads)
@@ -145,14 +145,14 @@ EncodeServer::process (shared_ptr<Socket> socket, struct timeval& after_read, st
 
 	gettimeofday (&after_read, 0);
 
-	Data encoded = dcp_video_frame.encode_locally ();
+	ArrayData encoded = dcp_video_frame.encode_locally ();
 
 	gettimeofday (&after_encode, 0);
 
 	try {
 		Socket::WriteDigestScope ds (socket);
 		socket->write (encoded.size());
-		socket->write (encoded.data().get(), encoded.size());
+		socket->write (encoded.data(), encoded.size());
 	} catch (std::exception& e) {
 		cerr << "Send failed; frame " << dcp_video_frame.index() << "\n";
 		LOG_ERROR ("Send failed; frame %1", dcp_video_frame.index());
diff --git a/src/lib/ffmpeg_image_proxy.cc b/src/lib/ffmpeg_image_proxy.cc
index f2b72059b..602185bb8 100644
--- a/src/lib/ffmpeg_image_proxy.cc
+++ b/src/lib/ffmpeg_image_proxy.cc
@@ -56,7 +56,7 @@ FFmpegImageProxy::FFmpegImageProxy (boost::filesystem::path path)
 
 }
 
-FFmpegImageProxy::FFmpegImageProxy (dcp::Data data)
+FFmpegImageProxy::FFmpegImageProxy (dcp::ArrayData data)
 	: _data (data)
 	, _pos (0)
 {
@@ -67,8 +67,8 @@ FFmpegImageProxy::FFmpegImageProxy (shared_ptr<cxml::Node>, shared_ptr<Socket> s
 	: _pos (0)
 {
 	uint32_t const size = socket->read_uint32 ();
-	_data = dcp::Data (size);
-	socket->read (_data.data().get(), size);
+	_data = dcp::ArrayData (size);
+	socket->read (_data.data(), size);
 }
 
 static int
@@ -90,7 +90,7 @@ FFmpegImageProxy::avio_read (uint8_t* buffer, int const amount)
 	if (to_do == 0) {
 		return AVERROR_EOF;
 	}
-	memcpy (buffer, _data.data().get() + _pos, to_do);
+	memcpy (buffer, _data.data() + _pos, to_do);
 	_pos += to_do;
 	return to_do;
 }
@@ -212,7 +212,7 @@ void
 FFmpegImageProxy::write_to_socket (shared_ptr<Socket> socket) const
 {
 	socket->write (_data.size());
-	socket->write (_data.data().get(), _data.size());
+	socket->write (_data.data(), _data.size());
 }
 
 bool
@@ -223,11 +223,7 @@ FFmpegImageProxy::same (shared_ptr<const ImageProxy> other) const
 		return false;
 	}
 
-	if (_data.size() != mp->_data.size()) {
-		return false;
-	}
-
-	return memcmp (_data.data().get(), mp->_data.data().get(), _data.size()) == 0;
+	return _data == mp->_data;
 }
 
 size_t
diff --git a/src/lib/ffmpeg_image_proxy.h b/src/lib/ffmpeg_image_proxy.h
index aa77003a4..62b99d280 100644
--- a/src/lib/ffmpeg_image_proxy.h
+++ b/src/lib/ffmpeg_image_proxy.h
@@ -19,7 +19,7 @@
 */
 
 #include "image_proxy.h"
-#include <dcp/data.h>
+#include <dcp/array_data.h>
 #include <boost/thread/mutex.hpp>
 #include <boost/filesystem.hpp>
 
@@ -27,7 +27,7 @@ class FFmpegImageProxy : public ImageProxy
 {
 public:
 	explicit FFmpegImageProxy (boost::filesystem::path);
-	explicit FFmpegImageProxy (dcp::Data);
+	explicit FFmpegImageProxy (dcp::ArrayData);
 	FFmpegImageProxy (boost::shared_ptr<cxml::Node> xml, boost::shared_ptr<Socket> socket);
 
 	Result image (
@@ -43,7 +43,7 @@ public:
 	int64_t avio_seek (int64_t const pos, int whence);
 
 private:
-	dcp::Data _data;
+	dcp::ArrayData _data;
 	mutable int64_t _pos;
 	/** Path of a file that this image came from, if applicable; stored so that
 	    failed-decode errors can give more detail.
diff --git a/src/lib/image.cc b/src/lib/image.cc
index 002c7df9a..03f1bf6dc 100644
--- a/src/lib/image.cc
+++ b/src/lib/image.cc
@@ -1278,7 +1278,7 @@ Image::png_error (char const * message)
 	throw EncodeError (String::compose ("Error during PNG write: %1", message));
 }
 
-dcp::Data
+dcp::ArrayData
 Image::as_png () const
 {
 	DCPOMATIC_ASSERT (bytes_per_pixel(0) == 4);
@@ -1317,5 +1317,5 @@ Image::as_png () const
 	png_destroy_write_struct (&png_ptr, &info_ptr);
 	png_free (png_ptr, row_pointers);
 
-	return dcp::Data (state.data, state.size);
+	return dcp::ArrayData (state.data, state.size);
 }
diff --git a/src/lib/image.h b/src/lib/image.h
index eab71c2b1..ab9b3c78a 100644
--- a/src/lib/image.h
+++ b/src/lib/image.h
@@ -31,6 +31,7 @@
 extern "C" {
 #include <libavutil/pixfmt.h>
 }
+#include <dcp/array_data.h>
 #include <dcp/colour_conversion.h>
 #include <boost/shared_ptr.hpp>
 #include <boost/enable_shared_from_this.hpp>
@@ -83,7 +84,7 @@ public:
 
 	size_t memory_used () const;
 
-	dcp::Data as_png () const;
+	dcp::ArrayData as_png () const;
 
 	void png_error (char const * message);
 
diff --git a/src/lib/j2k_encoder.cc b/src/lib/j2k_encoder.cc
index 64cd38147..18bb27645 100644
--- a/src/lib/j2k_encoder.cc
+++ b/src/lib/j2k_encoder.cc
@@ -127,7 +127,7 @@ J2KEncoder::end ()
 		LOG_GENERAL (N_("Encode left-over frame %1"), (*i)->index ());
 		try {
 			_writer->write (
-				(*i)->encode_locally(),
+				shared_ptr<dcp::Data>(new dcp::ArrayData((*i)->encode_locally())),
 				(*i)->index(),
 				(*i)->eyes()
 				);
@@ -296,12 +296,12 @@ try
 
 			lock.unlock ();
 
-			optional<Data> encoded;
+			shared_ptr<Data> encoded;
 
 			/* We need to encode this input */
 			if (server) {
 				try {
-					encoded = vf->encode_remotely (server.get ());
+					encoded.reset(new dcp::ArrayData(vf->encode_remotely(server.get())));
 
 					if (remote_backoff > 0) {
 						LOG_GENERAL ("%1 was lost, but now she is found; removing backoff", server->host_name ());
@@ -324,7 +324,7 @@ try
 			} else {
 				try {
 					LOG_TIMING ("start-local-encode thread=%1 frame=%2", thread_id(), vf->index());
-					encoded = vf->encode_locally ();
+					encoded.reset(new dcp::ArrayData(vf->encode_locally()));
 					LOG_TIMING ("finish-local-encode thread=%1 frame=%2", thread_id(), vf->index());
 				} catch (std::exception& e) {
 					/* This is very bad, so don't cope with it, just pass it on */
@@ -334,7 +334,7 @@ try
 			}
 
 			if (encoded) {
-				_writer->write (encoded.get(), vf->index (), vf->eyes ());
+				_writer->write (encoded, vf->index(), vf->eyes());
 				frame_done ();
 			} else {
 				lock.lock ();
diff --git a/src/lib/j2k_image_proxy.cc b/src/lib/j2k_image_proxy.cc
index 08ebc343c..064bbec7b 100644
--- a/src/lib/j2k_image_proxy.cc
+++ b/src/lib/j2k_image_proxy.cc
@@ -46,12 +46,12 @@ using std::make_pair;
 using boost::shared_ptr;
 using boost::optional;
 using boost::dynamic_pointer_cast;
-using dcp::Data;
+using dcp::ArrayData;
 using dcp::raw_convert;
 
 /** Construct a J2KImageProxy from a JPEG2000 file */
 J2KImageProxy::J2KImageProxy (boost::filesystem::path path, dcp::Size size, AVPixelFormat pixel_format)
-	: _data (path)
+	: _data (new dcp::ArrayData(path))
 	, _size (size)
 	, _pixel_format (pixel_format)
 	, _error (false)
@@ -60,13 +60,14 @@ J2KImageProxy::J2KImageProxy (boost::filesystem::path path, dcp::Size size, AVPi
 	DCPOMATIC_ASSERT (_pixel_format == AV_PIX_FMT_RGB48 || _pixel_format == AV_PIX_FMT_XYZ12LE);
 }
 
+
 J2KImageProxy::J2KImageProxy (
 	shared_ptr<const dcp::MonoPictureFrame> frame,
 	dcp::Size size,
 	AVPixelFormat pixel_format,
 	optional<int> forced_reduction
 	)
-	: _data (frame->j2k_size ())
+	: _data (frame)
 	, _size (size)
 	, _pixel_format (pixel_format)
 	, _forced_reduction (forced_reduction)
@@ -74,9 +75,9 @@ J2KImageProxy::J2KImageProxy (
 {
 	/* ::image assumes 16bpp */
 	DCPOMATIC_ASSERT (_pixel_format == AV_PIX_FMT_RGB48 || _pixel_format == AV_PIX_FMT_XYZ12LE);
-	memcpy (_data.data().get(), frame->j2k_data(), _data.size ());
 }
 
+
 J2KImageProxy::J2KImageProxy (
 	shared_ptr<const dcp::StereoPictureFrame> frame,
 	dcp::Size size,
@@ -84,7 +85,8 @@ J2KImageProxy::J2KImageProxy (
 	AVPixelFormat pixel_format,
 	optional<int> forced_reduction
 	)
-	: _size (size)
+	: _data (eye ? frame->left() : frame->right())
+	, _size (size)
 	, _eye (eye)
 	, _pixel_format (pixel_format)
 	, _forced_reduction (forced_reduction)
@@ -92,18 +94,9 @@ J2KImageProxy::J2KImageProxy (
 {
 	/* ::image assumes 16bpp */
 	DCPOMATIC_ASSERT (_pixel_format == AV_PIX_FMT_RGB48 || _pixel_format == AV_PIX_FMT_XYZ12LE);
-	switch (eye) {
-	case dcp::EYE_LEFT:
-		_data = Data (frame->left_j2k_size ());
-		memcpy (_data.data().get(), frame->left_j2k_data(), _data.size ());
-		break;
-	case dcp::EYE_RIGHT:
-		_data = Data (frame->right_j2k_size ());
-		memcpy (_data.data().get(), frame->right_j2k_data(), _data.size ());
-		break;
-	}
 }
 
+
 J2KImageProxy::J2KImageProxy (shared_ptr<cxml::Node> xml, shared_ptr<Socket> socket)
 	: _error (false)
 {
@@ -111,13 +104,14 @@ J2KImageProxy::J2KImageProxy (shared_ptr<cxml::Node> xml, shared_ptr<Socket> soc
 	if (xml->optional_number_child<int> ("Eye")) {
 		_eye = static_cast<dcp::Eye> (xml->number_child<int> ("Eye"));
 	}
-	_data = Data (xml->number_child<int> ("Size"));
+	shared_ptr<ArrayData> data(new ArrayData(xml->number_child<int>("Size")));
 	/* This only matters when we are using J2KImageProxy for the preview, which
 	   will never use this constructor (which is only used for passing data to
 	   encode servers).  So we can put anything in here.  It's a bit of a hack.
 	*/
 	_pixel_format = AV_PIX_FMT_XYZ12LE;
-	socket->read (_data.data().get (), _data.size ());
+	socket->read (data->data(), data->size());
+	_data = data;
 }
 
 int
@@ -144,7 +138,8 @@ J2KImageProxy::prepare (optional<dcp::Size> target_size) const
 	}
 
 	try {
-		shared_ptr<dcp::OpenJPEGImage> decompressed = dcp::decompress_j2k (const_cast<uint8_t*> (_data.data().get()), _data.size (), reduce);
+		/* XXX: should check that potentially trashing _data here doesn't matter */
+		shared_ptr<dcp::OpenJPEGImage> decompressed = dcp::decompress_j2k (const_cast<uint8_t*>(_data->data()), _data->size(), reduce);
 		_image.reset (new Image (_pixel_format, decompressed->size(), true));
 
 		int const shift = 16 - decompressed->precision (0);
@@ -202,13 +197,13 @@ J2KImageProxy::add_metadata (xmlpp::Node* node) const
 	if (_eye) {
 		node->add_child("Eye")->add_child_text (raw_convert<string> (static_cast<int> (_eye.get ())));
 	}
-	node->add_child("Size")->add_child_text (raw_convert<string> (_data.size ()));
+	node->add_child("Size")->add_child_text (raw_convert<string>(_data->size()));
 }
 
 void
 J2KImageProxy::write_to_socket (shared_ptr<Socket> socket) const
 {
-	socket->write (_data.data().get(), _data.size());
+	socket->write (_data->data(), _data->size());
 }
 
 bool
@@ -219,15 +214,11 @@ J2KImageProxy::same (shared_ptr<const ImageProxy> other) const
 		return false;
 	}
 
-	if (_data.size() != jp->_data.size()) {
-		return false;
-	}
-
-	return memcmp (_data.data().get(), jp->_data.data().get(), _data.size()) == 0;
+	return *_data == *jp->_data;
 }
 
-J2KImageProxy::J2KImageProxy (Data data, dcp::Size size, AVPixelFormat pixel_format)
-	: _data (data)
+J2KImageProxy::J2KImageProxy (ArrayData data, dcp::Size size, AVPixelFormat pixel_format)
+	: _data (new ArrayData(data))
 	, _size (size)
 	, _pixel_format (pixel_format)
 {
@@ -238,7 +229,7 @@ J2KImageProxy::J2KImageProxy (Data data, dcp::Size size, AVPixelFormat pixel_for
 size_t
 J2KImageProxy::memory_used () const
 {
-	size_t m = _data.size();
+	size_t m = _data->size();
 	if (_image) {
 		/* 3 components, 16-bits per pixel */
 		m += 3 * 2 * _image->size().width * _image->size().height;
diff --git a/src/lib/j2k_image_proxy.h b/src/lib/j2k_image_proxy.h
index 71bcffb2c..3eccc213d 100644
--- a/src/lib/j2k_image_proxy.h
+++ b/src/lib/j2k_image_proxy.h
@@ -19,8 +19,8 @@
 */
 
 #include "image_proxy.h"
+#include <dcp/array_data.h>
 #include <dcp/util.h>
-#include <dcp/data.h>
 #include <boost/thread/mutex.hpp>
 
 namespace dcp {
@@ -60,7 +60,7 @@ public:
 	bool same (boost::shared_ptr<const ImageProxy>) const;
 	int prepare (boost::optional<dcp::Size> = boost::optional<dcp::Size>()) const;
 
-	dcp::Data j2k () const {
+	boost::shared_ptr<const dcp::Data> j2k () const {
 		return _data;
 	}
 
@@ -74,9 +74,9 @@ private:
 	friend struct client_server_test_j2k;
 
 	/* For tests */
-	J2KImageProxy (dcp::Data data, dcp::Size size, AVPixelFormat pixel_format);
+	J2KImageProxy (dcp::ArrayData data, dcp::Size size, AVPixelFormat pixel_format);
 
-	dcp::Data _data;
+	boost::shared_ptr<const dcp::Data> _data;
 	dcp::Size _size;
 	boost::optional<dcp::Eye> _eye;
 	mutable boost::shared_ptr<Image> _image;
diff --git a/src/lib/player_video.cc b/src/lib/player_video.cc
index 10e798ed5..620245781 100644
--- a/src/lib/player_video.cc
+++ b/src/lib/player_video.cc
@@ -232,7 +232,7 @@ PlayerVideo::has_j2k () const
 	return _crop == Crop () && _out_size == j2k->size() && !_text && !_fade && !_colour_conversion;
 }
 
-Data
+shared_ptr<const dcp::Data>
 PlayerVideo::j2k () const
 {
 	shared_ptr<const J2KImageProxy> j2k = dynamic_pointer_cast<const J2KImageProxy> (_in);
diff --git a/src/lib/player_video.h b/src/lib/player_video.h
index 1a4a01d58..6043632c2 100644
--- a/src/lib/player_video.h
+++ b/src/lib/player_video.h
@@ -79,7 +79,7 @@ public:
 	bool reset_metadata (boost::shared_ptr<const Film> film, dcp::Size video_container_size, dcp::Size film_frame_size);
 
 	bool has_j2k () const;
-	dcp::Data j2k () const;
+	boost::shared_ptr<const dcp::Data> j2k () const;
 
 	Eyes eyes () const {
 		return _eyes;
diff --git a/src/lib/reel_writer.cc b/src/lib/reel_writer.cc
index a42c6182a..7ed79d818 100644
--- a/src/lib/reel_writer.cc
+++ b/src/lib/reel_writer.cc
@@ -67,6 +67,7 @@ using boost::dynamic_pointer_cast;
 #if BOOST_VERSION >= 106100
 using namespace boost::placeholders;
 #endif
+using dcp::ArrayData;
 using dcp::Data;
 using dcp::raw_convert;
 using namespace dcpomatic;
@@ -289,14 +290,14 @@ ReelWriter::check_existing_picture_asset (boost::filesystem::path asset)
 }
 
 void
-ReelWriter::write (optional<Data> encoded, Frame frame, Eyes eyes)
+ReelWriter::write (shared_ptr<const Data> encoded, Frame frame, Eyes eyes)
 {
 	if (!_picture_asset_writer) {
 		/* We're not writing any data */
 		return;
 	}
 
-	dcp::FrameInfo fin = _picture_asset_writer->write (encoded->data().get (), encoded->size());
+	dcp::FrameInfo fin = _picture_asset_writer->write (encoded->data(), encoded->size());
 	write_frame_info (frame, eyes, fin);
 	_last_written[eyes] = encoded;
 }
@@ -338,7 +339,7 @@ ReelWriter::repeat_write (Frame frame, Eyes eyes)
 	}
 
 	dcp::FrameInfo fin = _picture_asset_writer->write (
-		_last_written[eyes]->data().get(),
+		_last_written[eyes]->data(),
 		_last_written[eyes]->size()
 		);
 	write_frame_info (frame, eyes, fin);
@@ -762,15 +763,15 @@ ReelWriter::existing_picture_frame_ok (FILE* asset_file, shared_ptr<InfoFileHand
 
 	/* Read the data from the asset and hash it */
 	dcpomatic_fseek (asset_file, info.offset, SEEK_SET);
-	Data data (info.size);
-	size_t const read = fread (data.data().get(), 1, data.size(), asset_file);
+	ArrayData data (info.size);
+	size_t const read = fread (data.data(), 1, data.size(), asset_file);
 	LOG_GENERAL ("Read %1 bytes of asset data; wanted %2", read, info.size);
 	if (read != static_cast<size_t> (data.size ())) {
 		LOG_GENERAL ("Existing frame %1 is incomplete", frame);
 		ok = false;
 	} else {
 		Digester digester;
-		digester.add (data.data().get(), data.size());
+		digester.add (data.data(), data.size());
 		LOG_GENERAL ("Hash %1 vs %2", digester.get(), info.hash);
 		if (digester.get() != info.hash) {
 			LOG_GENERAL ("Existing frame %1 failed hash check", frame);
diff --git a/src/lib/reel_writer.h b/src/lib/reel_writer.h
index 17bfc7ba2..09c29adae 100644
--- a/src/lib/reel_writer.h
+++ b/src/lib/reel_writer.h
@@ -66,7 +66,7 @@ public:
 		boost::optional<std::string> content_summary
 		);
 
-	void write (boost::optional<dcp::Data> encoded, Frame frame, Eyes eyes);
+	void write (boost::shared_ptr<const dcp::Data> encoded, Frame frame, Eyes eyes);
 	void fake_write (int size);
 	void repeat_write (Frame frame, Eyes eyes);
 	void write (boost::shared_ptr<const AudioBuffers> audio);
@@ -104,7 +104,7 @@ private:
 	/** the first picture frame index that does not already exist in our MXF */
 	int _first_nonexistant_frame;
 	/** the data of the last written frame, if there is one */
-	boost::optional<dcp::Data> _last_written[EYES_COUNT];
+	boost::shared_ptr<const dcp::Data> _last_written[EYES_COUNT];
 	/** index of this reel within the DCP (starting from 0) */
 	int _reel_index;
 	/** number of reels in the DCP */
diff --git a/src/lib/string_text_file.cc b/src/lib/string_text_file.cc
index d3c56832d..793619003 100644
--- a/src/lib/string_text_file.cc
+++ b/src/lib/string_text_file.cc
@@ -38,7 +38,7 @@ using std::string;
 using boost::shared_ptr;
 using boost::scoped_array;
 using boost::optional;
-using dcp::Data;
+using dcp::ArrayData;
 using namespace dcpomatic;
 
 StringTextFile::StringTextFile (shared_ptr<const StringTextFileContent> content)
@@ -64,11 +64,11 @@ StringTextFile::StringTextFile (shared_ptr<const StringTextFileContent> content)
 	} else {
 		/* Text-based file; sort out its character encoding before we try to parse it */
 
-		Data in (content->path (0));
+		ArrayData in (content->path (0));
 
 		UErrorCode status = U_ZERO_ERROR;
 		UCharsetDetector* detector = ucsdet_open (&status);
-		ucsdet_setText (detector, reinterpret_cast<const char *> (in.data().get()), in.size(), &status);
+		ucsdet_setText (detector, reinterpret_cast<const char *>(in.data()), in.size(), &status);
 
 		UCharsetMatch const * match = ucsdet_detect (detector, &status);
 		char const * in_charset = ucsdet_getName (match, &status);
@@ -78,7 +78,7 @@ StringTextFile::StringTextFile (shared_ptr<const StringTextFileContent> content)
 		scoped_array<uint16_t> utf16 (new uint16_t[in.size() * 2]);
 		int const utf16_len = ucnv_toUChars (
 				to_utf16, reinterpret_cast<UChar*>(utf16.get()), in.size() * 2,
-				reinterpret_cast<const char *> (in.data().get()), in.size(),
+				reinterpret_cast<const char *>(in.data()), in.size(),
 				&status
 				);
 
diff --git a/src/lib/writer.cc b/src/lib/writer.cc
index d3fdc5128..346cbb0c2 100644
--- a/src/lib/writer.cc
+++ b/src/lib/writer.cc
@@ -66,6 +66,7 @@ using boost::optional;
 using namespace boost::placeholders;
 #endif
 using dcp::Data;
+using dcp::ArrayData;
 using namespace dcpomatic;
 
 Writer::Writer (shared_ptr<const Film> film, weak_ptr<Job> j)
@@ -130,7 +131,7 @@ Writer::~Writer ()
  *  @param eyes Eyes that this frame image is for.
  */
 void
-Writer::write (Data encoded, Frame frame, Eyes eyes)
+Writer::write (shared_ptr<const Data> encoded, Frame frame, Eyes eyes)
 {
 	boost::mutex::scoped_lock lock (_state_mutex);
 
@@ -426,7 +427,7 @@ try
 			case QueueItem::FULL:
 				LOG_DEBUG_ENCODE (N_("Writer FULL-writes %1 (%2)"), qi.frame, (int) qi.eyes);
 				if (!qi.encoded) {
-					qi.encoded = Data (_film->j2c_path (qi.reel, qi.frame, qi.eyes, false));
+					qi.encoded.reset (new ArrayData(_film->j2c_path(qi.reel, qi.frame, qi.eyes, false)));
 				}
 				reel.write (qi.encoded, qi.frame, qi.eyes);
 				++_full_written;
diff --git a/src/lib/writer.h b/src/lib/writer.h
index 71e04df96..fd7db69db 100644
--- a/src/lib/writer.h
+++ b/src/lib/writer.h
@@ -35,7 +35,7 @@
 #include <list>
 
 namespace dcp {
-	class Data;
+	class ArrayData;
 }
 
 namespace dcpomatic {
@@ -70,7 +70,7 @@ public:
 	} type;
 
 	/** encoded data for FULL */
-	boost::optional<dcp::Data> encoded;
+	boost::shared_ptr<const dcp::Data> encoded;
 	/** size of data for FAKE */
 	int size;
 	/** reel index */
@@ -105,7 +105,7 @@ public:
 
 	bool can_fake_write (Frame) const;
 
-	void write (dcp::Data, Frame, Eyes);
+	void write (boost::shared_ptr<const dcp::Data>, Frame, Eyes);
 	void fake_write (Frame, Eyes);
 	bool can_repeat (Frame) const;
 	void repeat (Frame, Eyes);
diff --git a/src/tools/server_test.cc b/src/tools/server_test.cc
index 99a6b4caf..b64970f62 100644
--- a/src/tools/server_test.cc
+++ b/src/tools/server_test.cc
@@ -46,7 +46,7 @@ using boost::bind;
 #if BOOST_VERSION >= 106100
 using namespace boost::placeholders;
 #endif
-using dcp::Data;
+using dcp::ArrayData;
 
 static shared_ptr<Film> film;
 static EncodeServerDescription* server;
@@ -63,8 +63,8 @@ process_video (shared_ptr<PlayerVideo> pvf)
 
 	++frame_count;
 
-	Data local_encoded = local->encode_locally ();
-	Data remote_encoded;
+	ArrayData local_encoded = local->encode_locally ();
+	ArrayData remote_encoded;
 
 	string remote_error;
 	try {
@@ -83,8 +83,8 @@ process_video (shared_ptr<PlayerVideo> pvf)
 		return;
 	}
 
-	uint8_t* p = local_encoded.data().get ();
-	uint8_t* q = remote_encoded.data().get ();
+	uint8_t* p = local_encoded.data();
+	uint8_t* q = remote_encoded.data();
 	for (int i = 0; i < local_encoded.size(); ++i) {
 		if (*p++ != *q++) {
 			cout << "\033[0;31mdata differ\033[0m at byte " << i << "\n";
diff --git a/test/client_server_test.cc b/test/client_server_test.cc
index 75cee85b3..22eeedbab 100644
--- a/test/client_server_test.cc
+++ b/test/client_server_test.cc
@@ -46,16 +46,16 @@ using boost::shared_ptr;
 using boost::thread;
 using boost::optional;
 using boost::weak_ptr;
-using dcp::Data;
+using dcp::ArrayData;
 
 void
-do_remote_encode (shared_ptr<DCPVideo> frame, EncodeServerDescription description, Data locally_encoded)
+do_remote_encode (shared_ptr<DCPVideo> frame, EncodeServerDescription description, ArrayData locally_encoded)
 {
-	Data remotely_encoded;
+	ArrayData remotely_encoded;
 	BOOST_REQUIRE_NO_THROW (remotely_encoded = frame->encode_remotely (description, 1200));
 
 	BOOST_REQUIRE_EQUAL (locally_encoded.size(), remotely_encoded.size());
-	BOOST_CHECK_EQUAL (memcmp (locally_encoded.data().get(), remotely_encoded.data().get(), locally_encoded.size()), 0);
+	BOOST_CHECK_EQUAL (memcmp (locally_encoded.data(), remotely_encoded.data(), locally_encoded.size()), 0);
 }
 
 BOOST_AUTO_TEST_CASE (client_server_test_rgb)
@@ -117,7 +117,7 @@ BOOST_AUTO_TEST_CASE (client_server_test_rgb)
 			)
 		);
 
-	Data locally_encoded = frame->encode_locally ();
+	ArrayData locally_encoded = frame->encode_locally ();
 
 	EncodeServer* server = new EncodeServer (true, 2);
 
@@ -203,7 +203,7 @@ BOOST_AUTO_TEST_CASE (client_server_test_yuv)
 			)
 		);
 
-	Data locally_encoded = frame->encode_locally ();
+	ArrayData locally_encoded = frame->encode_locally ();
 
 	EncodeServer* server = new EncodeServer (true, 2);
 
@@ -274,7 +274,7 @@ BOOST_AUTO_TEST_CASE (client_server_test_j2k)
 			)
 		);
 
-	Data raw_locally_encoded = raw_frame->encode_locally ();
+	ArrayData raw_locally_encoded = raw_frame->encode_locally ();
 
 	shared_ptr<PlayerVideo> j2k_pvf (
 		new PlayerVideo (
@@ -303,7 +303,7 @@ BOOST_AUTO_TEST_CASE (client_server_test_j2k)
 			)
 		);
 
-	Data j2k_locally_encoded = j2k_frame->encode_locally ();
+	ArrayData j2k_locally_encoded = j2k_frame->encode_locally ();
 
 	EncodeServer* server = new EncodeServer (true, 2);
 
diff --git a/test/crypto_test.cc b/test/crypto_test.cc
index e1069b42f..26c6748b8 100644
--- a/test/crypto_test.cc
+++ b/test/crypto_test.cc
@@ -29,12 +29,12 @@ using std::list;
 
 BOOST_AUTO_TEST_CASE (crypto_test)
 {
-	dcp::Data key (dcpomatic::crypto_key_length());
-	dcp::Data iv = dcpomatic::random_iv ();
+	dcp::ArrayData key (dcpomatic::crypto_key_length());
+	dcp::ArrayData iv = dcpomatic::random_iv ();
 
-	RAND_bytes (key.data().get(), dcpomatic::crypto_key_length());
+	RAND_bytes (key.data(), dcpomatic::crypto_key_length());
 
-	dcp::Data ciphertext = dcpomatic::encrypt ("Can you see any fish?", key, iv);
+	dcp::ArrayData ciphertext = dcpomatic::encrypt ("Can you see any fish?", key, iv);
 	BOOST_REQUIRE_EQUAL (dcpomatic::decrypt (ciphertext, key, iv), "Can you see any fish?");
 
 	key.data()[5]++;
diff --git a/test/test.cc b/test/test.cc
index 03e8768f4..9ac202b80 100644
--- a/test/test.cc
+++ b/test/test.cc
@@ -687,7 +687,7 @@ write_image (shared_ptr<const Image> image, boost::filesystem::path file)
 	png_destroy_write_struct (&png_ptr, &info_ptr);
 	png_free (png_ptr, row_pointers);
 
-	dcp::Data(state.data, state.size).write(file);
+	dcp::ArrayData(state.data, state.size).write(file);
 }