On Mon, Nov 7, 2011 at 10:01 PM, Ronald S. Bultje <rsbul...@gmail.com> wrote: > Hi, > > On Mon, Nov 7, 2011 at 12:46 PM, Reinhard Tartler <siret...@tauware.de> wrote: >> On Mo, Nov 07, 2011 at 18:20:50 (CET), Måns Rullgård wrote: >> >>> Reinhard Tartler <siret...@tauware.de> writes: >>> >>>> tags 647824 upstream >>>> stop >>>> >>>> On So, Nov 06, 2011 at 17:53:30 (CET), Harald Dunkel wrote: >>>> >>>>> Package: libav >>>>> Version: 4:0.7.2-1 >>>>> >>>>> If I build the current xbmc snapshot, then it dies at runtime when >>>>> creating thumbnails for wmv files. See http://trac.xbmc.org/ticket/11789 >>>>> for more details >>>>> >>>>> http://article.gmane.org/gmane.comp.video.ffmpeg.devel/134444 >>>>> >>>>> provides a workaround. Do you think this could be included in the >>>>> libav and libav-extra packages? >>>>> >>>> >>>> That patch does not apply to Debian's libav package. In fact, it seems >>>> that this bug is still present in the master branch. >>>> >>>> I was able to reproduce the segmentation fault using the following >>>> command in libav *master* (inspired by >>>> https://ffmpeg.org/trac/ffmpeg/ticket/397): >>>> >>>> ./ffmpeg -v 9 -loglevel 99 -i >>>> /srv/scratch/fate-suite/amv/MTV_high_res_320x240_sample_Penguin_Joke_MTV_from_WMV.amv >>>> -sws_flags fast_bilinear -vf "scale=640:480" -vframes 1 -vcodec png >>>> output.png >>>> >>>> Unforutnately, this (adapted) patch does not seem to fix the >>>> segmentation fault: >>>> >>>> diff --git a/libswscale/x86/swscale_template.c >>>> b/libswscale/x86/swscale_template.c >>>> index 5e7df5c..51ea303 100644 >>>> --- a/libswscale/x86/swscale_template.c >>>> +++ b/libswscale/x86/swscale_template.c >>>> @@ -1657,6 +1657,11 @@ static void RENAME(hyscale_fast)(SwsContext *c, >>>> int16_t *dst, >>>> DECLARE_ALIGNED(8, uint64_t, ebxsave); >>>> #endif >>>> >>>> + // HACK: gcc 4.6 no longer decrements esp, >>>> + // use this to make it reserve space for the call >>>> + // return address >>>> + void *dummy; >>> >>> The real problem here comes from hiding a call inside inline asm. >> >> That sounds pretty plausible. >> >> To make matters more complicated, I've tried disabling the MMX2 version >> of hyscale_fast with this patch: >> >> diff --git a/libswscale/x86/swscale_template.c >> b/libswscale/x86/swscale_template.c >> index 5e7df5c..b7a75b1 100644 >> --- a/libswscale/x86/swscale_template.c >> +++ b/libswscale/x86/swscale_template.c >> @@ -1843,7 +1843,7 @@ static av_cold void >> RENAME(sws_init_swScale)(SwsContext *c) >> if (c->srcBpc == 8 && c->dstBpc <= 10) { >> // Use the new MMX scaler if the MMX2 one can't be used (it is faster >> than the x86 ASM one). >> #if COMPILE_TEMPLATE_MMX2 >> - if (c->flags & SWS_FAST_BILINEAR && c->canMMX2BeUsed) >> + if (c->flags & SWS_FAST_BILINEAR && c->canMMX2BeUsed && 0) >> { >> c->hyscale_fast = RENAME(hyscale_fast); >> c->hcscale_fast = RENAME(hcscale_fast); >> >> AFAIUI, this makes swscale fallback to the slower hyScale() function and >> avoid this buggy implementation. Unfortunately, I get another >> segmentation fault here: > > That's not right, scaling coefficients are different so you need to > account for that. > > I'll have a look at this... I'm not against removing hscale_fast > altogether, including the scale coefficient specialcase handling etc.
any news on this? did you have a chance to look at this? -- regards, Reinhard _______________________________________________ libav-devel mailing list libav-devel@libav.org https://lists.libav.org/mailman/listinfo/libav-devel
