[MPlayer-users] MPEG/DVD crashing when taking screenshot

Roberto Togni rxt at rtogni.it
Mon Sep 21 22:42:28 CEST 2015


On Mon, 21 Sep 2015 01:05:59 -0400
Josh <joshf87 at live.com> wrote:

> On 9/14/2015 17:40, Roberto Togni wrote:
> > On Mon, 14 Sep 2015 20:59:46 +0200
> > Roberto Togni <rxt at rtogni.it> wrote:
> >
> >> On Sun, 13 Sep 2015 00:26:42 -0400
> >> Josh <joshf87 at live.com> wrote:
> >>
> >>> I compiled r37524 with a newer FFmpeg and got different but still
> >>> seemingly useless results from gdb so I ran Dr Memory, both logs are
> >>> included in the tar.xz. The logs themselves will get me queued for
> >>> moderation for being too big:
> >>>
> >>> http://sourceforge.net/projects/mplayerwin/files/Misc/mpl-bin-r37524-debug-2.tar.xz/download
> >>
> >> Hi,
> >>   just to keep you updated, I was able to reproduce it with your sample
> >>   and get a valid backtrace on linux.
> >>
> >> ...
> >> sending VFCTRL_SCREENSHOT!
> >>
> >> Program received signal SIGSEGV, Segmentation fault.
> >> 0x0000555555f68625 in yuv2rgb_X_c_template (hasAlpha=0,
> >>      target=AV_PIX_FMT_RGB24, y=13, dstW=2386, dest=0x555558be4680 "",
> >>      alpSrc=0x0, chrFilterSize=4, chrVSrc=0x5555572d9a48,
> >>      chrUSrc=0x55555711f128, chrFilter=0x5555572d76c8, lumFilterSize=1,
> >>      lumSrc=0x55555712c5e8, lumFilter=0x55555711e8ba, c=<optimized out>)
> >>      at libswscale/output.c:1340
> >> 1340	            Y1 += lumSrc[j][i * 2]     * lumFilter[j];
> >> (gdb) bt
> >> #0  0x0000555555f68625 in yuv2rgb_X_c_template (hasAlpha=0,
> >>      target=AV_PIX_FMT_RGB24, y=13, dstW=2386, dest=0x555558be4680 "",
> >>      alpSrc=0x0, chrFilterSize=4, chrVSrc=0x5555572d9a48,
> >>      chrUSrc=0x55555711f128, chrFilter=0x5555572d76c8, lumFilterSize=1,
> >>      lumSrc=0x55555712c5e8, lumFilter=0x55555711e8ba, c=<optimized out>)
> >>      at libswscale/output.c:1340
> >> #1  yuv2rgb24_X_c (c=0x555557223520, lumFilter=0x55555711e8ba,
> >>      lumSrc=0x55555712c5e8, lumFilterSize=1, chrFilter=0x5555572d76c8,
> >>      chrUSrc=0x55555711f128, chrVSrc=0x5555572d9a48, chrFilterSize=4,
> >>      alpSrc=0x0, dest=0x555558be4680 "", dstW=2386, y=13)
> >>      at libswscale/output.c:1515
> >> #2  0x0000555555f4dc9e in packed_vscale (c=<optimized out>,
> >>      desc=<optimized out>, sliceY=13, sliceH=<optimized out>)
> >>      at libswscale/vscale.c:129
> >> #3  0x0000555555f3dc81 in swscale (c=0x5555572b12c0,
> >> src=0x55555711e8a0, srcStride=0x1000, srcSliceY=1460470520,
> >> srcSliceH=1460470480, dst=0x55555711f128, dstStride=0x7fffffffca80) at
> >> libswscale/swscale.c:682 #4  0x0000555555f3ef4b in sws_scale
> >> (c=0x5555572b12c0, srcSlice=0x7fffffffca90, srcStride=0x55555712c5e8,
> >> srcSliceY=1, srcSliceH=1462597320, dst=0x7fffffffcab0,
> >> dstStride=0x5555570f4c60) at libswscale/swscale.c:1263
> >> #5  0x00005555558295da in draw_slice (vf=0x5555570f53b0,
> >> src=0x7fffffffcb90, stride=0x7fffffffcb80, w=1920, h=16, x=1460791456,
> >> y=16)
> >>      at libmpcodecs/vf_screenshot.c:64
> >> #6  0x0000555555826021 in draw_slice (s=<optimized out>, src=<optimized
> >> out>, offset=<optimized out>, y=<optimized out>, type=<optimized out>,
> >>      height=<optimized out>) at libmpcodecs/vd_ffmpeg.c:588
> >> #7  0x0000555555eb48e4 in ff_draw_horiz_band (avctx=0x5555570f69a0,
> >>      cur=<optimized out>, last=<optimized out>, y=16, h=16,
> >>      picture_structure=3, first_field=0, low_delay=0)
> >>      at libavcodec/mpegutils.c:77
> >> #8  0x0000555555b95135 in ff_mpeg_draw_horiz_band
> >> (s=s at entry=0x5555570f6e40, y=<optimized out>, h=<optimized out>) at
> >> libavcodec/mpegvideo.c:2720 #9  0x0000555555b60db5 in mpeg_decode_slice
> >> (s=s at entry=0x5555570f6e40, mb_y=mb_y at entry=1,
> >> buf=buf at entry=0x7fffffffcdd8, buf_size=buf_size at entry=2077) at
> >> libavcodec/mpeg12dec.c:1927 #10 0x0000555555b63b35 in decode_chunks
> >> (avctx=avctx at entry=0x5555570f69a0,
> >> picture=picture at entry=0x5555570f6760,
> >> got_output=got_output at entry=0x7fffffffcf60, buf=0x555556f088c0 "",
> >> buf_size=2111) at libavcodec/mpeg12dec.c:2759 #11 0x0000555555b645ab in
> >> mpeg_decode_frame (avctx=0x5555570f69a0, data=0x5555570f6760,
> >> got_output=0x7fffffffcf60, avpkt=<optimized out>) at
> >> libavcodec/mpeg12dec.c:2836 #12 0x0000555555c6762e in
> >> avcodec_decode_video2 (avctx=0x5555570f69a0, picture=0x5555570f6760,
> >> got_picture_ptr=0x7fffffffcf60, avpkt=0x7fffffffcf90) at
> >> libavcodec/utils.c:2096 ---Type <return> to continue, or q <return> to
> >> quit--- #13 0x0000555555826e5f in decode (sh=0x555556edc410,
> >> data=0x1000, len=1460848104, flags=-12400) at
> >> libmpcodecs/vd_ffmpeg.c:949 #14 0x0000555555775f4f in decode_video
> >> (sh_video=0x555556edc410, start=0x555556f088c0 "", in_size=2111,
> >> drop_frame=0, pts=1.083922266960144, full_frame=0x7fffffffd0b0)
> >>      at libmpcodecs/dec_video.c:398
> >> #15 0x00005555556dd772 in update_video (blit_frame=0x7fffffffd158)
> >>      at mplayer.c:2484
> >> #16 0x00005555556d0980 in main (argc=5, argv=0x7fffffffe288) at
> >> mplayer.c:3811
> >>
> >>
> >> You're probably right with the commit that broke it, I'm checking if
> >> swscale needs to be called differently now.
> >>
> >>
> > May be a problem in ffmpeg, see https://trac.ffmpeg.org/ticket/4850
> >
> > I can get a crash with similar backtrace with
> > ffmpeg -i mpeg_crash_screenshot.mpg -dsth 1096 -c png -f null /dev/null
> >
> >
> > Program received signal SIGSEGV, Segmentation fault.
> > 0x0000000000de5a57 in yuv2rgb_write (hasAlpha=0,
> > target=AV_PIX_FMT_RGB24,
> >      y=1088, _b=0x1e0f266, _g=0x1e0f266, _r=0x1e0f266, A2=0, A1=0,
> >      Y2=<optimized out>, Y1=<optimized out>, i=<optimized out>,
> >      _dest=0x7fffcc7f8040 "") at libswscale/output.c:1246
> > 1246	        dest[i * 6 + 0] = r_b[Y1];
> > (gdb) bt
> > #0  0x0000000000de5a57 in yuv2rgb_write (hasAlpha=0,
> > target=AV_PIX_FMT_RGB24,
> >      y=1088, _b=0x1e0f266, _g=0x1e0f266, _r=0x1e0f266, A2=0, A1=0,
> >      Y2=<optimized out>, Y1=<optimized out>, i=<optimized out>,
> >      _dest=0x7fffcc7f8040 "") at libswscale/output.c:1246
> > #1  yuv2rgb_X_c_template (hasAlpha=0, target=AV_PIX_FMT_RGB24, y=1088,
> >      dstW=1920, dest=0x7fffcc7f8040 "", alpSrc=0x0, chrFilterSize=4,
> >      chrVSrc=0x1b4dd30, chrUSrc=0x1b44c70, chrFilter=0x1b6e0c0,
> >      lumFilterSize=4, lumSrc=0x1b4e4f8, lumFilter=0x1b67440,
> > c=<optimized out>)
> >      at libswscale/output.c:1370
> > #2  yuv2rgb24_X_c (c=0x1ba75c0, lumFilter=0x1b67440, lumSrc=0x1b4e4f8,
> >      lumFilterSize=4, chrFilter=0x1b6e0c0, chrUSrc=0x1b44c70,
> >      chrVSrc=0x1b4dd30, chrFilterSize=4, alpSrc=0x0, dest=0x7fffcc7f8040
> > "",
> >      dstW=1920, y=1088) at libswscale/output.c:1515
> > #3  0x0000000000dca58e in packed_vscale (c=<optimized out>,
> >      desc=<optimized out>, sliceY=1088, sliceH=<optimized out>)
> >      at libswscale/vscale.c:129
> > #4  0x0000000000dc5d31 in swscale (c=0x1b4e980, src=0x1e0f266,
> > srcStride=0x0,
> >      srcSliceY=28632888, srcSliceH=28632848, dst=0x1b44c70,
> >      dstStride=0x7fffffffd6f0) at libswscale/swscale.c:682
> > #5  0x0000000000dc70ba in sws_scale (c=0x1b4e980,
> > srcSlice=0x7fffffffd700,
> >      srcStride=0x1b4e4f8, srcSliceY=4, srcSliceH=28762304,
> > dst=0x7fffffffd720,
> >      dstStride=0x7fffffffd7d0) at libswscale/swscale.c:1263
> > #6  0x000000000050a088 in scale_slice (y=<optimized out>,
> >      link=<optimized out>, field=<optimized out>, mul=<optimized out>,
> >      h=<optimized out>, sws=<optimized out>, cur_pic=<optimized out>,
> >      out_buf=<optimized out>) at libavfilter/vf_scale.c:477
> > #7  filter_frame (link=0x1b44520, in=0x1e0ecc0) at
> > libavfilter/vf_scale.c:579
> > #8  0x000000000049f1df in ff_filter_frame_framed (link=0x1b44520,
> >      frame=0x1e0ecc0) at libavfilter/avfilter.c:1089
> > #9  0x00000000004a1299 in ff_filter_frame (link=0x1b44520,
> > frame=0x1e0ecc0)
> >      at libavfilter/avfilter.c:1173
> > #10 0x000000000049f1df in ff_filter_frame_framed (link=0x1b44b20,
> >      frame=0x1e0ecc0) at libavfilter/avfilter.c:1089
> > #11 0x00000000004a1299 in ff_filter_frame (link=0x1b44b20,
> > frame=0x1e0ecc0)
> >      at libavfilter/avfilter.c:1173
> > #12 0x00000000004a53a2 in request_frame (link=0x1b44b20)
> >      at libavfilter/buffersrc.c:378
> > #13 0x00000000004a50d4 in av_buffersrc_add_frame_internal (
> >      ctx=ctx at entry=0x1b455e0, frame=frame at entry=0x1cca620,
> > flags=flags at entry=4)
> >      at libavfilter/buffersrc.c:180
> > #14 0x00000000004a55cd in av_buffersrc_add_frame_flags (ctx=0x1b455e0,
> >      frame=frame at entry=0x1cca620, flags=flags at entry=4)
> >      at libavfilter/buffersrc.c:105
> > #15 0x0000000000487272 in decode_video (ist=0x1b3ca00, pkt=<optimized
> > out>,
> >      got_output=<optimized out>) at ffmpeg.c:2179
> > #16 0x00000000004715d3 in process_input_packet (pkt=<optimized out>,
> >      ist=<optimized out>) at ffmpeg.c:2327
> > #17 process_input (file_index=<optimized out>) at ffmpeg.c:3833
> > #18 transcode_step () at ffmpeg.c:3921
> > #19 transcode () at ffmpeg.c:3974
> > #20 main (argc=28559872, argv=0x7fffffffe010) at ffmpeg.c:4157
> > (gdb)
> >
> >
> > Seems that the problem is related to slices, in MPlayer it works for the
> > first slice but fails for the 2nd (slice height is 16; offset 0 is ok,
> > offset 16 crashes).
> >
> >
> > The attached workaroud fixes the crash, but produces a wrong picture;
> > unless I missed some stupid detail, it should be equivalent to the old
> > code.
> >
> >
> > Ciao,
> >   Roberto
> >
> >
> >
> > _______________________________________________
> > MPlayer-users mailing list
> > MPlayer-users at mplayerhq.hu
> > https://lists.mplayerhq.hu/mailman/listinfo/mplayer-users
> >
> 
> I compiled the latest MPlayer trunk/FFmpeg master that has a fix for 
> FFmpeg #4850 and without your patch.
> 
> There is no crash but it simply quits (no screenshot saved) after 
> 'sending VFCTRL_SCREENSHOT!' when slices are enabled, with the exception 
> of mpeg_crash_ss_beetlejuice.mpg it quits slices or noslices.
Fix for #4850 did not stop the crash for me too.

What I found out is that if I force FFmpeg to use the old scaler
filters, everything works fine.

I was still unable to find out if something changed in the way you need
to use swscaler (I don't think so), if there is a bug in the new
swscaler, or if we always used it in the wrong way and we were just
lucky up to now.

I'm not much worried about vf_screenshot, but about all other uses of
the scaler code in the mail player.

If you want to test it, just comment out #define NEW_FILTER at the end
of ffmpeg/libswscale/swscale_internal.h and recompile everything.

This is a possible workaround for people using the internal ffmpeg copy
of MPlayer, it will not help if you use a system-wide install of ffmpeg.


Ciao,
 Roberto


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