[FFmpeg-trac] #8563(undetermined:new): overlay filter with simple PNG adds black fringe

[FFmpeg]

#8563: overlay filter with simple PNG adds black fringe
----------------------------------------+----------------------------------
             Reporter:  quasor          |                     Type:  defect
               Status:  new             |                 Priority:  normal
            Component:  undetermined    |                  Version:  4.2
             Keywords:  ffmpeg overlay  |               Blocked By:
             Blocking:                  |  Reproduced by developer:  0
Analyzed by developer:  0               |
----------------------------------------+----------------------------------
 Summary of the bug:
 How to reproduce:
 {{{
 ffmpeg -v verbose -y -i b.png -i a.png -filter_complex
 "[0:v]format=rgba[a];
     [1:v]format=rgba[b];
     [a][b]overlay,format=rgba"  out.png
 ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
   built with Apple clang version 11.0.0 (clang-1100.0.33.17)
   configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.2_2 --enable-shared
 --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-
 cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl
 --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus
 --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-
 libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-
 libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma
 --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-
 libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-
 libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-
 videotoolbox --disable-libjack --disable-indev=jack
   libavutil      56. 31.100 / 56. 31.100
   libavcodec     58. 54.100 / 58. 54.100
   libavformat    58. 29.100 / 58. 29.100
   libavdevice    58.  8.100 / 58.  8.100
   libavfilter     7. 57.100 /  7. 57.100
   libavresample   4.  0.  0 /  4.  0.  0
   libswscale      5.  5.100 /  5.  5.100
   libswresample   3.  5.100 /  3.  5.100
   libpostproc    55.  5.100 / 55.  5.100
 Input #0, png_pipe, from 'b.png':
   Duration: N/A, bitrate: N/A
     Stream #0:0: Video: png, 1 reference frame, rgba(pc), 100x100, 25 tbr,
 25 tbn, 25 tbc
 Input #1, png_pipe, from 'a.png':
   Duration: N/A, bitrate: N/A
     Stream #1:0: Video: png, 1 reference frame, rgba(pc), 100x100, 25 tbr,
 25 tbn, 25 tbc
 Stream mapping:
   Stream #0:0 (png) -> format
   Stream #1:0 (png) -> format
   format -> Stream #0:0 (png)
 Press [q] to stop, [?] for help
 [graph 0 input from stream 0:0 @ 0x7fa014c2f400] w:100 h:100 pixfmt:rgba
 tb:1/25 fr:25/1 sar:0/1 sws_param:flags=2
 [graph 0 input from stream 1:0 @ 0x7fa014c2f680] w:100 h:100 pixfmt:rgba
 tb:1/25 fr:25/1 sar:0/1 sws_param:flags=2
 [auto_scaler_0 @ 0x7fa014c30a80] w:iw h:ih flags:'bilinear' interl:0
 [Parsed_overlay_2 @ 0x7fa014c2e900] auto-inserting filter 'auto_scaler_0'
 between the filter 'Parsed_format_0' and the filter 'Parsed_overlay_2'
 [auto_scaler_1 @ 0x7fa014c31180] w:iw h:ih flags:'bilinear' interl:0
 [Parsed_overlay_2 @ 0x7fa014c2e900] auto-inserting filter 'auto_scaler_1'
 between the filter 'Parsed_format_1' and the filter 'Parsed_overlay_2'
 [auto_scaler_2 @ 0x7fa014c31640] w:iw h:ih flags:'bilinear' interl:0
 [Parsed_format_3 @ 0x7fa014c2f040] auto-inserting filter 'auto_scaler_2'
 between the filter 'Parsed_overlay_2' and the filter 'Parsed_format_3'
 [auto_scaler_0 @ 0x7fa014c30a80] w:100 h:100 fmt:rgba sar:0/1 -> w:100
 h:100 fmt:yuva420p sar:0/1 flags:0x2
 [auto_scaler_1 @ 0x7fa014c31180] w:100 h:100 fmt:rgba sar:0/1 -> w:100
 h:100 fmt:yuva420p sar:0/1 flags:0x2
 [Parsed_overlay_2 @ 0x7fa014c2e900] main w:100 h:100 fmt:yuva420p overlay
 w:100 h:100 fmt:yuva420p
 [Parsed_overlay_2 @ 0x7fa014c2e900] [framesync @ 0x7fa014c2ea28] Selected
 1/25 time base
 [Parsed_overlay_2 @ 0x7fa014c2e900] [framesync @ 0x7fa014c2ea28] Sync
 level 2
 [auto_scaler_2 @ 0x7fa014c31640] w:100 h:100 fmt:yuva420p sar:0/1 -> w:100
 h:100 fmt:rgba sar:0/1 flags:0x2
 Output #0, image2, to 'out.png':
   Metadata:
     encoder         : Lavf58.29.100
     Stream #0:0: Video: png, 1 reference frame, rgba, 100x100, q=2-31, 200
 kb/s, 25 fps, 25 tbn, 25 tbc (default)
     Metadata:
       encoder         : Lavc58.54.100 png
 [Parsed_overlay_2 @ 0x7fa014c2e900] [framesync @ 0x7fa014c2ea28] Sync
 level 1
 [Parsed_overlay_2 @ 0x7fa014c2e900] [framesync @ 0x7fa014c2ea28] Sync
 level 0
 No more output streams to write to, finishing.
 [AVIOContext @ 0x7fa014d12980] Statistics: 0 seeks, 1 writeouts
 frame=    1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A
 speed=7.36x
 video:3kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: unknown
 Input file #0 (b.png):
   Input stream #0:0 (video): 1 packets read (1151 bytes); 1 frames
 decoded;
   Total: 1 packets (1151 bytes) demuxed
 Input file #1 (a.png):
   Input stream #1:0 (video): 1 packets read (2244 bytes); 1 frames
 decoded;
   Total: 1 packets (2244 bytes) demuxed
 Output file #0 (out.png):
   Output stream #0:0 (video): 1 frames encoded; 1 packets muxed (3022
 bytes);
   Total: 1 packets (3022 bytes) muxed
 [AVIOContext @ 0x7fa014c26380] Statistics: 1151 bytes read, 0 seeks
 [AVIOContext @ 0x7fa014c26f00] Statistics: 2244 bytes read, 0 seeks
 }}}

 See attached expected and observed results

--
Ticket URL: <https://trac.ffmpeg.org/ticket/8563>
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