bugGnash - The GNU Flash player - Bugs: bug #24299, SWF8: unsupported blend modes


bug #24299: SWF8: unsupported blend modes

Submitter:  Benjamin Wolsey <bwy>
Submitted:  Thu 18 Sep 2008 04:20:42 PM UTC
Category:  renderer Severity:  3 - Normal
Release:  None Status:  Confirmed
Privacy:  Public Assigned to:  None
Open/Closed:  Open
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Mon 06 Oct 2008 11:18:52 AM UTC, comment #5: 

The swf is at


which does sort of play in gnash but with audio/video out of sync.


lesshaste <lesshaste>
Mon 06 Oct 2008 10:50:27 AM UTC, comment #4: 

I have a video with a related looking problem.  Here is the full log

11537] 11:37:42: UNIMPLEMENTED: SWF8 is not fully supported, trying anyway but don't expect it to work
11537] 11:37:42: UNIMPLEMENTED: FileAttributes tag in the SWF requests that network access is not granted to this movie (or application?) when loaded from the filesystem. Anyway Gnash won't care; use white/black listing in your .gnashrc instead
11537] 11:37:43: UNIMPLEMENTED: Button blend mode
11537] 11:37:43: UNIMPLEMENTED: DefineFontAlignZoneTag
11537] 11:37:43: TRACE: 692
11537] 11:37:44: TRACE: 1280
11537] 11:37:45: TRACE: 2080
11537] 11:37:45: UNIMPLEMENTED:   FIXME: tagtype = 74
11537] 11:37:45: TRACE: 2622

gnash 0.8.2 plays the opening screen but then seems to stop.

I have put the .flv file up at



lesshaste <lesshaste>
Thu 18 Sep 2008 04:44:17 PM UTC, comment #3: 

My other case for this:

These are good examples of why using proprietary tools
to produce SWF isn't a good idea. Use of blend modes
for doing these kind of things is completely dumb, but
prevents free players to play your stuff :/

Sandro Santilli <strk>
Group Member
Thu 18 Sep 2008 04:41:14 PM UTC, comment #2: 


Last time I had this issue the blend mode was 'erase'
which meant the character should have been rendered
as a kind of mask.

Blend mode and Bitmap filters are the big feature missing
for full SWF8 support. I'd start from renderers in trying
to design interfaces for the core (which currently parses
but doesn't even store those info).

With bastiaan busy on GST and Udo busy with something else
I don't know who could be looking at this.

Want to have fun bwy ? :)

Sandro Santilli <strk>
Group Member
Thu 18 Sep 2008 04:39:20 PM UTC, comment #1: 

Looks like the bug might be blend mode.

Benjamin Wolsey <bwy>
Group Member
Thu 18 Sep 2008 04:20:42 PM UTC, original submission:  

The video mentioned in bug #21284 plays perfectly well, but Gnash draws a rectangle on top of it so that nothing in the SWF plays.

The object is a DefineShape, id 1, set to be the full size of the SWF and with a solid fill (FillStyle 1).

Interestingly, if you make it coloured (e.g. cyan), the pp makes the visible background cyan, whereas Gnash seems just to draw a cyan strip across the top.

Not sure whether the parsing is incorrect or the display.

Benjamin Wolsey <bwy>
Group Member


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    Follow 5 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2008-09-18 strk SummaryGnash puts rectangle on top of entire SWF. SWF8: unsupported blend modes
    2008-09-18 strk CategoryNone renderer
        StatusNone Confirmed
        Carbon-Copy- Added udog
        Carbon-Copy- Added bjacques

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