Re: read beyond buffer

Thanks for the answer. Now I wonder what values I should use for padding.
Will zeros do or should I use a pattern like 0 0 1? I'm asking because in 
some places in the xvid code I see calls to method check_resync_marker and 
the rsync marker is 1.

Martin


Am Wednesday, 1. November 2006 18:39 schrieb Michael Militzer:
> Hello Martin,
>
> Xvid cvs head and 1.1.2 versions perform a cross check before accessing
> *(bs->tail+2) if XVID_SAFE_BS_TAIL is defined in bitstream.h. This check
> however costs performance. Hence, we recommend you should not use the
> XVID_SAFE_BS_TAIL flag but instead pad your input buffers to 8 bytes if
> any possible.
>
> Regards,
> Michael
>
> Quoting Martin Kuball <[email protected]>:
> > Hi!
> >
> > I'm writing an application that uses libxvid 1.1.0 to decode mpeg4
> > videos. I noticed that when calling
> >
> > 	frameStruct.bitstream = input_buffer;
> > 	frameStruct.length = length;  //length of input_buffer
> > 	xvid_decore(handle, XVID_DEC_DECODE, &frameStruct, &statusStruct);
> >
> > xvid is sometimes accesing bytes beyond input_buffer[length-1]. This
> > happens everytime a userdata frame is red and somethimes with vops,
> > too. I could not find any documentation saying that you need to
> > provide extra space at the end of the buffer. And actually if you
> > provide a length field in the API I consider it as a bug if it is not
> > honoured.
> >
> > So what is necessary to make it work reliably?
> >
> > By the way I could not check with version 1.1.1 because I was not able
> > to download it. Seems to be some broken links on the web page.
> >
> > Martin
> > _______________________________________________
> > XviD-users mailing list
> > [email protected]
> > http://list.xvid.org/mailman/listinfo/xvid-users
>
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