[FFmpeg-devel] [PATCH] libavfilter-soc: Fix a buffer reuse bug in the movie filter

[Vitor Sessak]

Martin Storsj? wrote:
> Hi,
> 
> There's a slight bug in the movie source filter in libavfilter; it hands 
> out a buffer pointing to the codec internal frame buffer, which the 
> receiving filter may store. This can lead to bugs where a stored frame 
> reference changes content without further warning.
> 
> This doesn't seem to be visible with most videos, but I encountered it 
> with the following movie:
> http://movies.apple.com/movies/sony_pictures/casino_royale/casino_royale-tlr1_h640w.mov
> 
> To trigger the bug, run the following command:
> ./ffplay casino_royale-tlr1_h640w.mov -vfilters "movie=0:mov:casino_royale-tlr1_h640w.mov [over1], [in] [over1] overlay=100:100 [out]"
> 
> In this case, frames are displayed a bit too soon/too late.
> 
> If a scale filter is plugged between the movie and overlay filters, this 
> effect disappears.
> 
> The attached patch corrects this bug, by marking the output video buffer 
> with the correct permission flags (in the same way as in the buffer video 
> source filter).

Looks correct to me, applied.

-Vitor