Re: [Ming-dev] Bug in display_list.c SWFDisplayList_writeBlocks()

[strk <st...@ke...>]

Alex, can you provide a testcase for the problem for inclusion
in the new testsuite ?

--strk;

On Wed, Nov 22, 2006 at 02:06:58PM -0800, Alex Curylo wrote:
> There's a bug in SWFDisplayList_writeBlocks() in displaylist.c which causes
> objects after a non-embedded video stream to not be written out. The
> problematic bit is
> 
>         /* for each videostream in movie add VideoFrame */
>          if(character && ((SWFBlock)character)->type ==
> SWF_DEFINEVIDEOSTREAM) {
>              SWFBlock video =
> SWFVideoStream_getVideoFrame((SWFVideoStream)character);
>              
>              if(!video)
>                  break;
>          
>              /* well it isn't really clear why we need the place-block here
>               * its not metioned in the flash-specs
>               * but its not working without */
>              if((item->flags & ITEM_NEW) == 0)
>              {
>                  frame =
> SWFVideoStream_getFrameNumber((SWFVideoFrame)video);
>                  placeVideo = newSWFPlaceObject2Block(item->depth);
>                  SWFPlaceObject2Block_setRatio(placeVideo, frame);
>                  SWFPlaceObject2Block_setMove(placeVideo);
>                  SWFBlockList_addBlock(blocklist, (SWFBlock)placeVideo);
>              }
>                  
>               
>              SWFBlockList_addBlock(blocklist, video);
>          }
> 
> What happens if you're using NetStream instead of including the video
> directly is that SWFVideoStream_getVideoFrame() returns NULL, and the
> consequent break stops anything after the video canvas getting added.
> 
> An easy fix is simply not breaking on NULL.
> 
>              if (NULL != video) // which it will be for streaming video
>              {
>                 /* well it isn't really clear why we need the place-block
> here
>                 * its not metioned in the flash-specs
>                 * but its not working without */
>                 if((item->flags & ITEM_NEW) == 0)
>                 {
>                     frame =
> SWFVideoStream_getFrameNumber((SWFVideoFrame)video);
>                     placeVideo = newSWFPlaceObject2Block(item->depth);
>                     SWFPlaceObject2Block_setRatio(placeVideo, frame);
>                     SWFPlaceObject2Block_setMove(placeVideo);
>                     SWFBlockList_addBlock(blocklist, (SWFBlock)placeVideo);
>                 }
>               
>                 SWFBlockList_addBlock(blocklist, video);
>              }
> 
> I presume a proper fix would involve figuring out whether the video stream
> is embedded or not to know if NULL is an expected return value, but it's not
> clear to me how to do that.
> 
> 
> 
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