libv4l: improve mr97310a decompression

Bring mr97310a decompression in line with the latest gphoto code, resulting
in a much better picure

Priority: normal

Signed-off-by: Theodore Kilgore <kilgota@banach.math.auburn.edu>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/lib/ChangeLog b/lib/ChangeLog
index 58191b3..82da375 100644 (file)
--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,3 +1,8 @@
+libv4l-0.6.3
+------------
+* Add more laptop models to the upside down devices table
+* Improved mr97310a decompression
+
 libv4l-0.6.2
 ------------
 * Add more laptop models to the upside down devices table

diff --git a/lib/libv4lconvert/mr97310a.c b/lib/libv4lconvert/mr97310a.c
index e6ce94b..3b7afee 100644 (file)
--- a/lib/libv4lconvert/mr97310a.c
+++ b/lib/libv4lconvert/mr97310a.c
@@ -55,19 +55,19 @@ static void init_mr97310a_decoder(void)
                        len = 3;
                } else if ((i & 0xf0) == 0x80) {
                        /* code 1000 */
-                       val = +7;
+                       val = +8;
                        len = 4;
                } else if ((i & 0xf0) == 0x90) {
                        /* code 1001 */
-                       val = -7;
+                       val = -8;
                        len = 4;
                } else if ((i & 0xf0) == 0xf0) {
                        /* code 1111 */
-                       val = -15;
+                       val = -20;
                        len = 4;
                } else if ((i & 0xf8) == 0xe0) {
                        /* code 11100 */
-                       val = +15;
+                       val = +20;
                        len = 5;
                } else if ((i & 0xf8) == 0xe8) {
                        /* code 11101xxxxx */
@@ -152,14 +152,17 @@ void v4lconvert_decode_mr97310a(const unsigned char *inp, unsigned char *outp,
                                } else if (col < 2) {
                                        /* left column: relative to top pixel */
                                        /* initial estimate */
-                                       val += (2*tp + 2*trp + 1)/4;
+                                       val += (tp + trp)/2;
                                } else if (col > width - 3) {
                                        /* left column: relative to top pixel */
-                                       val += (2*tp + 2*tlp + 1)/4;
-                               /* main area: average of left and top pixel */
+                                       val += (tp + lp + tlp + 1)/3;
+                               /* main area: weighted average of tlp, trp,
+                                * lp, and tp */
                                } else {
+                                       tlp>>=1;
+                                       trp>>=1;
                                        /* initial estimate for predictor */
-                                       val += (2*lp + tp + trp + 1)/4;
+                                       val += (lp + tp + tlp + trp + 1)/3;
                                }
                        }
                        /* store pixel */
@@ -167,6 +170,5 @@ void v4lconvert_decode_mr97310a(const unsigned char *inp, unsigned char *outp,
                        ++col;
                }
        }
-
        return;
 }