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authorCameron Esfahani <dirty@apple.com>2020-01-20 21:00:52 -0800
committerGerd Hoffmann <kraxel@redhat.com>2020-01-21 07:29:03 +0100
commit557ba0e57200014bd4f453f6516f02b61bdfc782 (patch)
treede3705821464e65fbef38cb3b6abc9b2ab502508
parent0780ec7be82dd4781e9fd216b5d99a125882ff5a (diff)
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vnc: prioritize ZRLE compression over ZLIB
In my investigation, ZRLE always compresses better than ZLIB so prioritize ZRLE over ZLIB, even if the client hints that ZLIB is preferred. zlib buffer is always reset in zrle_compress_data(), so using offset to calculate next_out and avail_out is useless. Signed-off-by: Cameron Esfahani <dirty@apple.com> Message-Id: <b5d129895d08a90d0a2a6183b95875bacfa998b8.1579582674.git.dirty@apple.com> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
-rw-r--r--ui/vnc-enc-zrle.c4
-rw-r--r--ui/vnc.c11
2 files changed, 11 insertions, 4 deletions
diff --git a/ui/vnc-enc-zrle.c b/ui/vnc-enc-zrle.c
index 17fd28a..b4f71e3 100644
--- a/ui/vnc-enc-zrle.c
+++ b/ui/vnc-enc-zrle.c
@@ -98,8 +98,8 @@ static int zrle_compress_data(VncState *vs, int level)
/* set pointers */
zstream->next_in = vs->zrle->zrle.buffer;
zstream->avail_in = vs->zrle->zrle.offset;
- zstream->next_out = vs->zrle->zlib.buffer + vs->zrle->zlib.offset;
- zstream->avail_out = vs->zrle->zlib.capacity - vs->zrle->zlib.offset;
+ zstream->next_out = vs->zrle->zlib.buffer;
+ zstream->avail_out = vs->zrle->zlib.capacity;
zstream->data_type = Z_BINARY;
/* start encoding */
diff --git a/ui/vnc.c b/ui/vnc.c
index 3e8d1f1..1d7138a 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -2071,8 +2071,15 @@ static void set_encodings(VncState *vs, int32_t *encodings, size_t n_encodings)
break;
#endif
case VNC_ENCODING_ZLIB:
- vs->features |= VNC_FEATURE_ZLIB_MASK;
- vs->vnc_encoding = enc;
+ /*
+ * VNC_ENCODING_ZRLE compresses better than VNC_ENCODING_ZLIB.
+ * So prioritize ZRLE, even if the client hints that it prefers
+ * ZLIB.
+ */
+ if ((vs->features & VNC_FEATURE_ZRLE_MASK) == 0) {
+ vs->features |= VNC_FEATURE_ZLIB_MASK;
+ vs->vnc_encoding = enc;
+ }
break;
case VNC_ENCODING_ZRLE:
vs->features |= VNC_FEATURE_ZRLE_MASK;