[MPlayer-dev-eng] GIF help needed

[Roberto Togni]

On 2003.01.22 21:47 Joey Parrish wrote:
> Hello,
> 
> I submitted a patch before to add GIF demux/decode support to MPlayer.
> It was rejected because it made the decoder dependant on the demuxer
> and it didn't really decode so much as colormap and blit.
> 
> On Arpi's suggestion, I made another patch where GIF demuxer colormaps
> it all into RGB24 and outputs raw RGB.  (Instead of sending indexed
> values to decoder and having decoder map them to RGB24.)
> 
> The problem is that so far, only the wrong way to do it actually
> works.
> The version that needs no vd_gif displays garbled colors.  I have the
> feeling that I'm doing something stupid, so I would really appreciate
> it
> if someone could look at the patches and help me find my problem.

Hi Joey.
I'm looking at your patch.
I tried the right_broken version, and it displays the first frame of 
the gif correctly for me. Then, the vd_raw decoder complains about 
frame being too small.
If i got your vd_gif right, the next frames can be subpictures of the 
first frame, overwriteing only a portion of the output picture (i'm 
talking about the gif->Image.Top and gif->Image.Left stuff).
If that's true, it won't work without the vd_gif module, unless you 
store the previous frame in some private area into the demuxer, update 
it, and pass the complete frame to the decoder, since the vd_raw module 
expects a full size frame (the same is true even if you use RGB8 
format).

I'll have a deeper look at it, but i don't think i'll be able to do it 
tonight.

Update: with the attached patch (copied the Top/Left stuff from vd_gif) 
i was able to play gifs that don't use partial update (mostly untested)

The code also have problems with some static gifs (progressive ones? 
i'll have to check).


Ciao,
  Roberto
-------------- next part --------------
--- demux_gif.c	Wed Jan 22 22:41:22 2003
+++ demux_gif.c.r	Wed Jan 22 23:54:28 2003
@@ -115,13 +115,22 @@
   if (effective_map == NULL) effective_map = gif->SColorMap;
 
   {
-    int x;
-    for (x = 0; x < len; x++) {
-      dp->buffer[(x * 3) + 0] = effective_map->Colors[buf[x]].Red;
-      dp->buffer[(x * 3) + 1] = effective_map->Colors[buf[x]].Green;
-      dp->buffer[(x * 3) + 2] = effective_map->Colors[buf[x]].Blue;
+    int x, y;
+    for (y = 0; y < gif->Image.Height; y++) {
+      unsigned char *drow = dp->buffer;
+      unsigned char *gbuf = buf + (y * gif->Image.Width);
+
+      drow += gif->Image.Width * (y + gif->Image.Top)*3;
+      drow += gif->Image.Left * 3;
+
+      for (x = 0; x < gif->Image.Width; x++) {
+        drow[(x * 3) + 0] = effective_map->Colors[gbuf[x]].Red;
+        drow[(x * 3) + 1] = effective_map->Colors[gbuf[x]].Green;
+        drow[(x * 3) + 2] = effective_map->Colors[gbuf[x]].Blue;
+      }
     }
   }
+  
 
   free(buf);