Change JPEG quality/subsampling map to produce meaningful compression ratios, as defined by the VirtualGL project study of rendered frames from SPECviewperf 9
git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@3666 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/common/rfb/TightEncoder.cxx b/common/rfb/TightEncoder.cxx
index 159ebbf..f9684b9 100644
--- a/common/rfb/TightEncoder.cxx
+++ b/common/rfb/TightEncoder.cxx
@@ -44,17 +44,35 @@
// FIXME: Is this comment obsolete?
//
+// NOTE: The JPEG quality and subsampling levels below were obtained
+// experimentally by the VirtualGL Project. They represent the approximate
+// average compression ratios listed below, as measured across the set of
+// every 10th frame in the SPECviewperf 9 benchmark suite.
+//
+// 9 = JPEG quality 100, no subsampling (ratio ~= 10:1)
+// [this should be lossless, except for round-off error]
+// 8 = JPEG quality 92, no subsampling (ratio ~= 20:1)
+// [this should be perceptually lossless, based on current research]
+// 7 = JPEG quality 86, no subsampling (ratio ~= 25:1)
+// 6 = JPEG quality 79, no subsampling (ratio ~= 30:1)
+// 5 = JPEG quality 77, 4:2:2 subsampling (ratio ~= 40:1)
+// 4 = JPEG quality 62, 4:2:2 subsampling (ratio ~= 50:1)
+// 3 = JPEG quality 42, 4:2:2 subsampling (ratio ~= 60:1)
+// 2 = JPEG quality 41, 4:2:0 subsampling (ratio ~= 70:1)
+// 1 = JPEG quality 29, 4:2:0 subsampling (ratio ~= 80:1)
+// 0 = JPEG quality 15, 4:2:0 subsampling (ratio ~= 100:1)
+
const TIGHT_CONF TightEncoder::conf[10] = {
- { 512, 32, 6, 0, 0, 0, 4, 10, 1 }, // 0
- { 2048, 64, 6, 1, 1, 1, 8, 25, 1 }, // 1
- { 4096, 128, 8, 3, 3, 2, 24, 25, 0 }, // 2
- { 8192, 256, 12, 5, 5, 2, 32, 50, 1 }, // 3
- { 16384, 512, 12, 6, 7, 3, 32, 50, 0 }, // 4
- { 32768, 512, 12, 7, 8, 4, 32, 75, 1 }, // 5
- { 65536, 1024, 16, 7, 8, 5, 32, 75, 0 }, // 6
- { 65536, 1024, 16, 8, 9, 6, 64, 83, 0 }, // 7
- { 65536, 2048, 24, 9, 9, 7, 64, 92, 0 }, // 8
- { 65536, 2048, 32, 9, 9, 9, 96,100, 0 } // 9
+ { 512, 32, 6, 0, 0, 0, 4, 15, SUBSAMP_420 }, // 0
+ { 2048, 64, 6, 1, 1, 1, 8, 29, SUBSAMP_420 }, // 1
+ { 4096, 128, 8, 3, 3, 2, 24, 41, SUBSAMP_420 }, // 2
+ { 8192, 256, 12, 5, 5, 2, 32, 42, SUBSAMP_422 }, // 3
+ { 16384, 512, 12, 6, 7, 3, 32, 62, SUBSAMP_422 }, // 4
+ { 32768, 512, 12, 7, 8, 4, 32, 77, SUBSAMP_422 }, // 5
+ { 65536, 1024, 16, 7, 8, 5, 32, 79, SUBSAMP_NONE }, // 6
+ { 65536, 1024, 16, 8, 9, 6, 64, 86, SUBSAMP_NONE }, // 7
+ { 65536, 2048, 24, 9, 9, 7, 64, 92, SUBSAMP_NONE }, // 8
+ { 65536, 2048, 32, 9, 9, 9, 96,100, SUBSAMP_NONE } // 9
};
const int TightEncoder::defaultCompressLevel = 6;
diff --git a/common/rfb/TightEncoder.h b/common/rfb/TightEncoder.h
index 35f2f59..a36340f 100644
--- a/common/rfb/TightEncoder.h
+++ b/common/rfb/TightEncoder.h
@@ -30,12 +30,19 @@
namespace rfb {
+ enum subsampEnum {
+ SUBSAMP_NONE,
+ SUBSAMP_422,
+ SUBSAMP_420
+ };
+
struct TIGHT_CONF {
unsigned int maxRectSize, maxRectWidth;
unsigned int monoMinRectSize;
int idxZlibLevel, monoZlibLevel, rawZlibLevel;
int idxMaxColorsDivisor;
- int jpegQuality, jpegSubSample;
+ int jpegQuality;
+ subsampEnum jpegSubSample;
};
//
diff --git a/common/rfb/tightEncode.h b/common/rfb/tightEncode.h
index f2192bb..bf27453 100644
--- a/common/rfb/tightEncode.h
+++ b/common/rfb/tightEncode.h
@@ -537,10 +537,17 @@
jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, s_pjconf->jpegQuality, TRUE);
- if (s_pjconf->jpegSubSample) {
+
+ switch (s_pjconf->jpegSubSample) {
+ case SUBSAMP_420:
cinfo.comp_info[0].h_samp_factor = 2;
cinfo.comp_info[0].v_samp_factor = 2;
- } else {
+ break;
+ case SUBSAMP_422:
+ cinfo.comp_info[0].h_samp_factor = 2;
+ cinfo.comp_info[0].v_samp_factor = 1;
+ break;
+ default:
cinfo.comp_info[0].h_samp_factor = 1;
cinfo.comp_info[0].v_samp_factor = 1;
}