[Qemu-devel] [PATCH] Add JPEG encoding to VNC server

[Alexander Graf]

We know most of the tight protocol already, so implementing JPEG is rather
easy, especially considering that I had this implementation lying around
still anyways.

The big concern Anthony raised about JPEG compression is that as soon as you
use JPEG, CopyRect looks ugly for most use cases and most users probably don't
want it anyways.

So the road I went for this patch was to only enable JPEG encoding when it's
the only available choice. Allow any other protocols? You don't get JPEG then.

While this might sound like it renders the whole implementation useless, it
does make sense to implement it nevertheless. I have some ideas to implement
progressive encodings for video.

So when we'd detect that one region is updated a lot in a short about of time
with content that zlib can't really handle well, we'd just send a really low
quality JPEG first and then send the update after a timer if the region wasn't
updated within that timeframe.

But this is all ideas so far. For now the JPEG implementation is stand alone,
but would enable either me or someone else who'd like to do it worlds of
encoding fun :-).

Also, if you're daring, you can always see if JPEG performs good for your
specific VNC workload and at least have the chance to use it.

Signed-off-by: Alexander Graf <address@hidden>
---
 Makefile.target |    4 +
 configure       |   24 ++++++++
 vnc.c           |  178 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 vnc.h           |    9 +++
 4 files changed, 214 insertions(+), 1 deletions(-)

diff --git a/Makefile.target b/Makefile.target
index 49ba08d..f1dd54d 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -303,6 +303,10 @@ CPPFLAGS += $(VNC_SASL_CFLAGS)
 LIBS += $(VNC_SASL_LIBS)
 endif
 
+ifdef CONFIG_VNC_JPEG
+LIBS += $(CONFIG_VNC_JPEG_LIBS)
+endif
+
 ifdef CONFIG_BLUEZ
 LIBS += $(BLUEZ_LIBS)
 endif
diff --git a/configure b/configure
index 8160bed..67fe51a 100755
--- a/configure
+++ b/configure
@@ -175,6 +175,7 @@ fmod_inc=""
 oss_lib=""
 vnc_tls="yes"
 vnc_sasl="yes"
+vnc_jpeg="yes"
 bsd="no"
 linux="no"
 solaris="no"
@@ -428,6 +429,8 @@ for opt do
   ;;
   --disable-vnc-sasl) vnc_sasl="no"
   ;;
+  --disable-jpeg) vnc_jpeg="no"
+  ;;
   --disable-slirp) slirp="no"
   ;;
   --disable-vde) vde="no"
@@ -649,6 +652,7 @@ echo "  --disable-xen            disable xen backend driver 
support"
 echo "  --disable-brlapi         disable BrlAPI"
 echo "  --disable-vnc-tls        disable TLS encryption for VNC server"
 echo "  --disable-vnc-sasl       disable SASL encryption for VNC server"
+echo "  --disable-jpeg           disable JPEG compression for VNC server"
 echo "  --disable-curses         disable curses output"
 echo "  --disable-curl           disable curl connectivity"
 echo "  --disable-bluez          disable bluez stack connectivity"
@@ -994,6 +998,21 @@ if $cc $ARCH_CFLAGS -o $TMPE $TMPC > /dev/null 2> 
/dev/null ; then
 fi
 
 ##########################################
+# VNC JPEG detection
+if test "$vnc_jpeg" = "yes" ; then
+cat > $TMPC <<EOF
+#include <jpeglib.h>
+int main(void) { jpeg_compress_struct s; jpeg_create_compress(&s); return 0; }
+EOF
+    vnc_jpeg_libs="-ljpeg"
+    if $cc $ARCH_CFLAGS -o $TMPE ${OS_CFLAGS} $TMPC $vnc_jpeg_libs > /dev/null 
2> /dev/null ; then
+       :
+    else
+       vnc_tls="no"
+    fi
+fi
+
+##########################################
 # vde libraries probe
 if test "$vde" = "yes" ; then
   vde=no
@@ -1452,6 +1471,7 @@ if test "$vnc_sasl" = "yes" ; then
     echo "    SASL CFLAGS    $vnc_sasl_cflags"
     echo "    SASL LIBS      $vnc_sasl_libs"
 fi
+echo "VNC JPEG support  $vnc_jpeg"
 if test -n "$sparc_cpu"; then
     echo "Target Sparc Arch $sparc_cpu"
 fi
@@ -1604,6 +1624,10 @@ fi
 if test "$fnmatch" = "yes" ; then
   echo "CONFIG_FNMATCH=y" >> $config_host_mak
 fi
+if test "$vnc_jpeg" = "yes" ; then
+  echo "CONFIG_VNC_JPEG=y" >> $config_host_mak
+  echo "CONFIG_VNC_JPEG_LIBS=$vnc_jpeg_libs" >> $config_host_mak
+fi
 qemu_version=`head $source_path/VERSION`
 echo "VERSION=$qemu_version" >>$config_host_mak
 echo "PKGVERSION=$pkgversion" >>$config_host_mak
diff --git a/vnc.c b/vnc.c
index 903dd95..4e0c967 100644
--- a/vnc.c
+++ b/vnc.c
@@ -635,9 +635,171 @@ static void send_framebuffer_update_zlib(VncState *vs, 
int x, int y, int w, int
     vs->output.offset = new_offset;
 }
 
+#ifdef CONFIG_VNC_JPEG
+/* This is called once per encoding */
+static void jpeg_init_destination(j_compress_ptr cinfo)
+{
+    VncState *vs = (VncState*)cinfo->client_data;
+    Buffer *buffer = &vs->jpeg_buffer;
+
+    cinfo->dest->next_output_byte = (JOCTET *)buffer->buffer + buffer->offset;
+    cinfo->dest->free_in_buffer = (size_t)(buffer->capacity - buffer->offset);
+}
+
+/* This is called when we ran out of buffer (shouldn't happen!) */
+static boolean jpeg_empty_output_buffer(j_compress_ptr cinfo)
+{
+    VncState *vs = (VncState*)cinfo->client_data;
+    Buffer *buffer = &vs->jpeg_buffer;
+
+    buffer->offset = buffer->capacity;
+    buffer_reserve(buffer, 2048);
+    jpeg_init_destination(cinfo);
+    return TRUE;
+}
+
+/* This is called when we are done processing data */
+static void jpeg_term_destination(j_compress_ptr cinfo)
+{
+    VncState *vs = (VncState*)cinfo->client_data;
+    Buffer *buffer = &vs->jpeg_buffer;
+
+    buffer->offset = buffer->capacity - cinfo->dest->free_in_buffer;
+}
+
+
+static void vnc_send_compact_size(VncState *vs, int len) 
+{
+    char buf[3];
+    int lpc = 0;
+    int bytes = 0;
+
+    /* Adapted from SendCompressedData() in 
Xvnc/programs/Xserver/hw/vnc/tight.c */
+    buf[bytes++] = len & 0x7F;
+    if (len > 0x7F) {
+       buf[bytes-1] |= 0x80;
+       buf[bytes++] = len >> 7 & 0x7F;
+       if (len > 0x3FFF) {
+           buf[bytes-1] |= 0x80;
+           buf[bytes++] = len >> 14 & 0xFF;
+       }
+    }
+
+    for(lpc = 0; lpc < bytes; lpc++) {
+       vnc_write_u8(vs, buf[lpc]);
+    }
+}
+
+static void jpeg_row2pixel(VncState *vs, char *in, char *out, int len)
+{
+    char *pi = in;
+    char *po = out;
+    int depth = vs->server.ds->pf.bytes_per_pixel;
+    int i;
+
+    for (i = 0; i < len; i++) {
+        uint32_t v;
+        uint8_t r, g, b;
+        switch (depth) {
+            case 1:
+                po[0] = pi[0];
+                po[1] = pi[0];
+                po[2] = pi[0];
+                continue;
+                break;
+            case 2:
+                v = *((uint16_t*)pi);
+                break;
+            case 4:
+                v = *((uint32_t*)pi);
+                break;
+        }
+        r = ((((v & vs->server.ds->pf.rmask) >> vs->server.ds->pf.rshift)
+            << vs->clientds.pf.rbits) >> vs->server.ds->pf.rbits);
+        g = ((((v & vs->server.ds->pf.gmask) >> vs->server.ds->pf.gshift)
+            << vs->clientds.pf.gbits) >> vs->server.ds->pf.gbits);
+        b = ((((v & vs->server.ds->pf.bmask) >> vs->server.ds->pf.bshift)
+            << vs->clientds.pf.bbits) >> vs->server.ds->pf.bbits);
+
+        po[0] = r;
+        po[1] = g;
+        po[2] = b;
+
+        pi += depth;
+        po += 3; // RGB
+    }
+}
+
+static void send_framebuffer_update_tight(VncState *vs, int x, int y, int w, 
int h)
+{
+    struct jpeg_compress_struct cinfo;
+    struct jpeg_error_mgr jerr;
+    uint8_t *row = ds_get_data(vs->ds) +
+                   y * ds_get_linesize(vs->ds) +
+                   x * ds_get_bytes_per_pixel(vs->ds);
+    int dy;
+    JSAMPROW row_pointer[1];
+
+    if(vnc_has_feature(vs, VNC_FEATURE_HEXTILE) && (w * h) < 300) {
+       /* Below a certain size its actually more efficient to send hextiles
+        * Take a rough stab in the dark at 300 for text-based displays */
+        send_framebuffer_update_hextile(vs, x, y, w, h);
+        return;
+    }
+    
+    vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_TIGHT);
+
+    // XXX For now let's be stupid and always send JPEG data. Tight can do a 
lot more!
+
+    // Indicate its a Jpeg data stream
+    vnc_write_u8(vs, VNC_TIGHT_CCB_TYPE_JPEG);
+
+    // Compress data
+    cinfo.client_data = vs;
+    cinfo.err = jpeg_std_error(&jerr);
+    jpeg_create_compress(&cinfo);
+    cinfo.image_width = w;
+    cinfo.image_height = h;
+    cinfo.input_components = 3;
+    cinfo.in_color_space = JCS_RGB;
+
+    jpeg_set_defaults(&cinfo);
+    jpeg_set_quality(&cinfo, (vs->tight_quality+1) * 10, TRUE);
+
+    buffer_reserve(&vs->jpeg_buffer, 1024);
+    vs->jpeg_dst_manager.init_destination = jpeg_init_destination;
+    vs->jpeg_dst_manager.empty_output_buffer = jpeg_empty_output_buffer;
+    vs->jpeg_dst_manager.term_destination = jpeg_term_destination;
+    cinfo.dest = &vs->jpeg_dst_manager;
+
+    jpeg_start_compress(&cinfo, TRUE);
+
+    row_pointer[0] = qemu_malloc(3 * w);
+    for (dy = 0; dy < h; dy++) {
+        jpeg_row2pixel(vs, (char*)row, (char*)row_pointer[0], w);
+        jpeg_write_scanlines(&cinfo, row_pointer, 1);
+        row += ds_get_linesize(vs->ds);
+    }
+    qemu_free(row_pointer[0]);
+
+    jpeg_finish_compress(&cinfo);
+    jpeg_destroy_compress(&cinfo);
+
+    VNC_DEBUG("JPEG: Sending %d bytes of jpeg data\n", 
(int)vs->jpeg_buffer.offset);
+    vnc_send_compact_size(vs, vs->jpeg_buffer.offset);
+    vnc_write(vs, vs->jpeg_buffer.buffer, vs->jpeg_buffer.offset);
+    buffer_reset(&vs->jpeg_buffer);
+}
+#endif /* CONFIG_VNC_JPEG */
+
 static void send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
 {
     switch(vs->vnc_encoding) {
+#ifdef CONFIG_VNC_JPEG
+        case VNC_ENCODING_TIGHT:
+           send_framebuffer_update_tight(vs, x, y, w, h);
+           break;
+#endif /* CONFIG_VNC_JPEG */
         case VNC_ENCODING_ZLIB:
             send_framebuffer_update_zlib(vs, x, y, w, h);
             break;
@@ -1552,7 +1714,7 @@ static void set_encodings(VncState *vs, int32_t 
*encodings, size_t n_encodings)
 
     vnc_zlib_init(vs);
     vs->features = 0;
-    vs->vnc_encoding = 0;
+    vs->vnc_encoding = -1;
     vs->tight_compression = 9;
     vs->tight_quality = 9;
     vs->absolute = -1;
@@ -1574,6 +1736,17 @@ static void set_encodings(VncState *vs, int32_t 
*encodings, size_t n_encodings)
             vs->features |= VNC_FEATURE_ZLIB_MASK;
             vs->vnc_encoding = enc;
             break;
+        case VNC_ENCODING_TIGHT:
+#ifdef CONFIG_VNC_JPEG
+            buffer_reset(&vs->jpeg_buffer);
+#endif
+            vs->features |= VNC_FEATURE_TIGHT_MASK;
+
+            /* We don't want to do JPEG encoding by accident, so only
+             * enable it when it's the only choice. */
+            if (vs->vnc_encoding == -1)
+                vs->vnc_encoding = enc;
+            break;
         case VNC_ENCODING_DESKTOPRESIZE:
             vs->features |= VNC_FEATURE_RESIZE_MASK;
             break;
@@ -1601,6 +1774,9 @@ static void set_encodings(VncState *vs, int32_t 
*encodings, size_t n_encodings)
         }
     }
 
+    if (vs->vnc_encoding == -1)
+        vs->vnc_encoding = VNC_ENCODING_RAW;
+
     check_pointer_type_change(vs, kbd_mouse_is_absolute());
 }
 
diff --git a/vnc.h b/vnc.h
index 3ae95f3..b57081f 100644
--- a/vnc.h
+++ b/vnc.h
@@ -33,6 +33,10 @@
 #include "audio/audio.h"
 #include <zlib.h>
 
+#ifdef CONFIG_VNC_JPEG
+#include <jpeglib.h>
+#endif /* CONFIG_VNC_JPEG */
+
 #include "keymaps.h"
 
 // #define _VNC_DEBUG 1
@@ -161,6 +165,11 @@ struct VncState
     Buffer zlib_tmp;
     z_stream zlib_stream[4];
 
+#ifdef CONFIG_VNC_JPEG
+    Buffer jpeg_buffer;
+    struct jpeg_destination_mgr jpeg_dst_manager;
+#endif /* CONFIG_VNC_JPEG */
+
     VncState *next;
 };
 
-- 
1.6.0.2