[FFmpeg-cvslog] pngdec: fix decoding of right column for 2/4bpp

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Thu Jan  3 23:40:22 2013 +0100| [9e36d9e4ed2a43c363a54d963eb399a6e9623365] | committer: Michael Niedermayer

pngdec: fix decoding of right column for 2/4bpp

Fixes Ticket1146

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9e36d9e4ed2a43c363a54d963eb399a6e9623365
---

 libavcodec/pngdec.c |   18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index eb6e1a6..21b742c 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -784,15 +784,22 @@ static int decode_frame(AVCodecContext *avctx,
         int i, j;
         uint8_t *pd = s->current_picture->data[0];
         for(j=0; j < s->height; j++) {
+            i = s->width/4;
             if (s->color_type == PNG_COLOR_TYPE_PALETTE){
-            for(i=s->width/4-1; i>=0; i--) {
+                if ((s->width&3) >= 3) pd[4*i+2]= (pd[i]>>2)&3;
+                if ((s->width&3) >= 2) pd[4*i+1]= (pd[i]>>4)&3;
+                if ((s->width&3) >= 1) pd[4*i+0]=  pd[i]>>6;
+                for(i--; i>=0; i--) {
                 pd[4*i+3]=  pd[i]    &3;
                 pd[4*i+2]= (pd[i]>>2)&3;
                 pd[4*i+1]= (pd[i]>>4)&3;
                 pd[4*i+0]=  pd[i]>>6;
             }
             } else {
-                for(i=s->width/4-1; i>=0; i--) {
+                if ((s->width&3) >= 3) pd[4*i+2]= ((pd[i]>>2)&3)*0x55;
+                if ((s->width&3) >= 2) pd[4*i+1]= ((pd[i]>>4)&3)*0x55;
+                if ((s->width&3) >= 1) pd[4*i+0]= ( pd[i]>>6   )*0x55;
+                for(i--; i>=0; i--) {
                     pd[4*i+3]= ( pd[i]    &3)*0x55;
                     pd[4*i+2]= ((pd[i]>>2)&3)*0x55;
                     pd[4*i+1]= ((pd[i]>>4)&3)*0x55;
@@ -806,13 +813,16 @@ static int decode_frame(AVCodecContext *avctx,
         int i, j;
         uint8_t *pd = s->current_picture->data[0];
         for(j=0; j < s->height; j++) {
+            i=s->width/2;
             if (s->color_type == PNG_COLOR_TYPE_PALETTE){
-            for(i=s->width/2-1; i>=0; i--) {
+                if (s->width&1) pd[2*i+0]= pd[i]>>4;
+                for(i--; i>=0; i--) {
                 pd[2*i+1]= pd[i]&15;
                 pd[2*i+0]= pd[i]>>4;
             }
             } else {
-                for(i=s->width/2-1; i>=0; i--) {
+                if (s->width&1) pd[2*i+0]= (pd[i]>>4)*0x11;
+                for(i--; i>=0; i--) {
                     pd[2*i+1]= (pd[i]&15)*0x11;
                     pd[2*i+0]= (pd[i]>>4)*0x11;
                 }