[FFmpeg-trac] #7230(avfilter:new): gradfun errors

[FFmpeg]

#7230: gradfun errors
----------------------------------+---------------------------------------
             Reporter:  shekh     |                     Type:  defect
               Status:  new       |                 Priority:  normal
            Component:  avfilter  |                  Version:  unspecified
             Keywords:  filter    |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
----------------------------------+---------------------------------------
 I see several issues.
 1. bad x86 asm
 Resulting images are obviously different with/without asm optimization.

 How to reproduce:
 {{{
 ffmpeg.exe -cpuflags 0 -i test.png -vf gradfun=40:28 test_c.png
 ffmpeg version N-91152-g7c333dc6a7 Copyright (c) 2000-2018 the FFmpeg
 developers
   built with gcc 7.3.0 (GCC)
   configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-
 bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass
 --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-
 libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
 --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr
 --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack
 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2
 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-
 libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa
 --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx
 --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-
 nvenc --enable-nvdec --enable-dxva2 --enable-avisynth
   libavutil      56. 18.102 / 56. 18.102
   libavcodec     58. 19.102 / 58. 19.102
   libavformat    58. 16.100 / 58. 16.100
   libavdevice    58.  4.100 / 58.  4.100
   libavfilter     7. 24.100 /  7. 24.100
   libswscale      5.  2.100 /  5.  2.100
   libswresample   3.  2.100 /  3.  2.100
   libpostproc    55.  2.100 / 55.  2.100
 Input #0, png_pipe, from 'test.png':
   Duration: N/A, bitrate: N/A
     Stream #0:0: Video: png, gray(pc), 400x200 [SAR 2835:2835 DAR 2:1], 25
 tbr, 25 tbn, 25 tbc
 File 'test_c.png' already exists. Overwrite ? [y/N] Stream mapping:
   Stream #0:0 -> #0:0 (png (native) -> png (native))
 Press [q] to stop, [?] for help
 Output #0, image2, to 'test_c.png':
   Metadata:
     encoder         : Lavf58.16.100
     Stream #0:0: Video: png, gray, 400x200 [SAR 2835:2835 DAR 2:1],
 q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
     Metadata:
       encoder         : Lavc58.19.102 png
 frame=    1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A
 speed=2.67x
 video:36kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: unknown
 }}}
 {{{
 ffmpeg.exe -i test.png -vf gradfun=40:28 test_mmx.png
 ffmpeg version N-91152-g7c333dc6a7 Copyright (c) 2000-2018 the FFmpeg
 developers
   built with gcc 7.3.0 (GCC)
   configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-
 bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass
 --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-
 libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
 --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr
 --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack
 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2
 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-
 libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa
 --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx
 --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-
 nvenc --enable-nvdec --enable-dxva2 --enable-avisynth
   libavutil      56. 18.102 / 56. 18.102
   libavcodec     58. 19.102 / 58. 19.102
   libavformat    58. 16.100 / 58. 16.100
   libavdevice    58.  4.100 / 58.  4.100
   libavfilter     7. 24.100 /  7. 24.100
   libswscale      5.  2.100 /  5.  2.100
   libswresample   3.  2.100 /  3.  2.100
   libpostproc    55.  2.100 / 55.  2.100
 Input #0, png_pipe, from 'test.png':
   Duration: N/A, bitrate: N/A
     Stream #0:0: Video: png, gray(pc), 400x200 [SAR 2835:2835 DAR 2:1], 25
 tbr, 25 tbn, 25 tbc
 Stream mapping:
   Stream #0:0 -> #0:0 (png (native) -> png (native))
 Press [q] to stop, [?] for help
 Output #0, image2, to 'test_mmx.png':
   Metadata:
     encoder         : Lavf58.16.100
     Stream #0:0: Video: png, gray, 400x200 [SAR 2835:2835 DAR 2:1],
 q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
     Metadata:
       encoder         : Lavc58.19.102 png
 frame=    1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A
 speed=2.67x
 video:36kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: unknown
 }}}

 2. Output is quantized in 2x2 blocks. This is far lower quality than even
 8-bit buffer would allow, but it is using 16-bit buffer. Something must be
 wrong.
 Visible on same test images.

 3. Out of bounds read, cannot provide test

 https://github.com/FFmpeg/FFmpeg/blob/7c333dc6a7fe1dc991f484c70ed7990d6ee62724/libavfilter/vf_gradfun.c#L95-L100
 {{{
         if (y < height - r) {
             int mod = ((y + r) / 2) % r;
             uint16_t *buf0 = buf + mod * bstride;
             uint16_t *buf1 = buf + (mod ? mod - 1 : r - 1) * bstride;
             int x, v;
             ctx->blur_line(dc, buf0, buf1, src + (y + r) * src_linesize,
 src_linesize, width / 2);
 ...
 }}}

 Looks like it should be
 {{{
 {{{
         if (y < height - r - 1) {
 ...
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/7230>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker