[FFmpeg-trac] #4926(undetermined:new): Visual artifacts while scaling PNG(rgba) -> PNG(rgba)

FFmpeg trac at avcodec.org
Wed Oct 14 13:01:56 CEST 2015


#4926: Visual artifacts while scaling PNG(rgba) -> PNG(rgba)
-------------------------------------+-------------------------------------
             Reporter:  pszemus      |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 Visual artifacts while scaling PNG(rgba) -> PNG(rgba)

 How to reproduce:
 {{{
 $ ~/ffmpeg/ffmpeg -y -v debug -i
 http://storage2.sportowefakty.pl.sds.o2.pl/tags/5611842b1f09f2_20295212.png
 -s 34x44 /tmp/tmp.png
 ffmpeg version N-75978-g3da6c7e Copyright (c) 2000-2015 the FFmpeg
 developers
   built with gcc 4.8.3 (GCC) 20140911 (Red Hat 4.8.3-9)
   configuration: --prefix=/home/pszemus/ffmpeg/build --enable-pic
 --enable-pthreads --enable-libmp3lame --enable-version3 --enable-
 libopencore-amrnb --enable-libopencore-amrwb --enable-libfaac --enable-gpl
 --enable-nonfree --enable-libvpx --enable-libvorbis --enable-libx264
 --enable-protocol=https --enable-openssl --extra-
 cflags=-I/opt/WP/common.libs/include --extra-
 ldflags='-L/opt/WP/common.libs/lib -ldl'
   libavutil      55.  3.100 / 55.  3.100
   libavcodec     57.  5.100 / 57.  5.100
   libavformat    57.  3.100 / 57.  3.100
   libavdevice    57.  0.100 / 57.  0.100
   libavfilter     6. 11.100 /  6. 11.100
   libswscale      4.  0.100 /  4.  0.100
   libswresample   2.  0.100 /  2.  0.100
   libpostproc    54.  0.100 / 54.  0.100
 Splitting the commandline.
 Reading option '-y' ... matched as option 'y' (overwrite output files)
 with argument '1'.
 Reading option '-v' ... matched as option 'v' (set logging level) with
 argument 'debug'.
 Reading option '-i' ... matched as input file with argument
 'http://storage2.sportowefakty.pl.sds.o2.pl/tags/5611842b1f09f2_20295212.png'.
 Reading option '-s' ... matched as option 's' (set frame size (WxH or
 abbreviation)) with argument '34x44'.
 Reading option '/tmp/tmp.png' ... matched as output file.
 Finished splitting the commandline.
 Parsing a group of options: global .
 Applying option y (overwrite output files) with argument 1.
 Applying option v (set logging level) with argument debug.
 Successfully parsed a group of options.
 Parsing a group of options: input file
 http://storage2.sportowefakty.pl.sds.o2.pl/tags/5611842b1f09f2_20295212.png.
 Successfully parsed a group of options.
 Opening an input file:
 http://storage2.sportowefakty.pl.sds.o2.pl/tags/5611842b1f09f2_20295212.png.
 [http @ 0x24cdc80] request: GET /tags/5611842b1f09f2_20295212.png HTTP/1.1
 User-Agent: Lavf/57.3.100
 Accept: */*
 Range: bytes=0-
 Connection: close
 Host: storage2.sportowefakty.pl.sds.o2.pl
 Icy-MetaData: 1


 [png_pipe @ 0x24cd380] Format png_pipe probed with size=2048 and score=99
 [png_pipe @ 0x24cd380] Before avformat_find_stream_info() pos: 0 bytes
 read:2573 seeks:0
 [png_pipe @ 0x24cd380] After avformat_find_stream_info() pos: 191689 bytes
 read:191689 seeks:0 frames:1
 Input #0, png_pipe, from
 'http://storage2.sportowefakty.pl.sds.o2.pl/tags/5611842b1f09f2_20295212.png':
   Duration: N/A, bitrate: N/A
     Stream #0:0, 1, 1/25: Video: png, 1 reference frame, rgba(pc),
 2200x2827 (0x0), 1/25, 25 tbr, 25 tbn, 25 tbc
 Successfully opened the file.
 Parsing a group of options: output file /tmp/tmp.png.
 Applying option s (set frame size (WxH or abbreviation)) with argument
 34x44.
 Successfully parsed a group of options.
 Opening an output file: /tmp/tmp.png.
 Successfully opened the file.
 detected 2 logical cores
 [graph 0 input from stream 0:0 @ 0x24d1a40] Setting 'video_size' to value
 '2200x2827'
 [graph 0 input from stream 0:0 @ 0x24d1a40] Setting 'pix_fmt' to value
 '28'
 [graph 0 input from stream 0:0 @ 0x24d1a40] Setting 'time_base' to value
 '1/25'
 [graph 0 input from stream 0:0 @ 0x24d1a40] Setting 'pixel_aspect' to
 value '0/1'
 [graph 0 input from stream 0:0 @ 0x24d1a40] Setting 'sws_param' to value
 'flags=2'
 [graph 0 input from stream 0:0 @ 0x24d1a40] Setting 'frame_rate' to value
 '25/1'
 [graph 0 input from stream 0:0 @ 0x24d1a40] w:2200 h:2827 pixfmt:rgba
 tb:1/25 fr:25/1 sar:0/1 sws_param:flags=2
 [scaler for output stream 0:0 @ 0x24d6c60] Setting 'w' to value '34'
 [scaler for output stream 0:0 @ 0x24d6c60] Setting 'h' to value '44'
 [scaler for output stream 0:0 @ 0x24d6c60] Setting 'flags' to value
 'bicubic'
 [scaler for output stream 0:0 @ 0x24d6c60] w:34 h:44 flags:'bicubic'
 interl:0
 [format @ 0x24d7800] compat: called with
 args=[rgb24|rgba|rgb48be|rgba64be|pal8|gray|ya8|gray16be|ya16be|monob]
 [format @ 0x24d7800] Setting 'pix_fmts' to value
 'rgb24|rgba|rgb48be|rgba64be|pal8|gray|ya8|gray16be|ya16be|monob'
 [AVFilterGraph @ 0x24d6060] query_formats: 5 queried, 4 merged, 0 already
 done, 0 delayed
 [swscaler @ 0x24e14e0] Forcing full internal H chroma due to input having
 non subsampled chroma
 sws: initFilter failed
 [scaler for output stream 0:0 @ 0x24d6c60] w:2200 h:2827 fmt:rgba sar:0/1
 -> w:34 h:44 fmt:rgba sar:0/1 flags:0x4
 Output #0, image2, to '/tmp/tmp.png':
   Metadata:
     encoder         : Lavf57.3.100
     Stream #0:0, 0, 1/25: Video: png, 1 reference frame, rgba, 34x44,
 1/25, q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
     Metadata:
       encoder         : Lavc57.5.100 png
 Stream mapping:
   Stream #0:0 -> #0:0 (png (native) -> png (native))
 Press [q] to stop, [?] for help
 Cliping frame in rate conversion by 0.000008
 [AVIOContext @ 0x276b9e0] Statistics: 0 seeks, 1 writeouts
 [output stream 0:0 @ 0x24d7080] EOF on sink link output stream
 0:0:default.
 No more output streams to write to, finishing.
 frame=    1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A
 video:3kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: unknown
 Input file #0
 (http://storage2.sportowefakty.pl.sds.o2.pl/tags/5611842b1f09f2_20295212.png):
   Input stream #0:0 (video): 1 packets read (191689 bytes); 1 frames
 decoded;
   Total: 1 packets (191689 bytes) demuxed
 Output file #0 (/tmp/tmp.png):
   Output stream #0:0 (video): 1 frames encoded; 1 packets muxed (2577
 bytes);
   Total: 1 packets (2577 bytes) muxed
 1 frames successfully decoded, 0 decoding errors
 [AVIOContext @ 0x24d9400] Statistics: 191689 bytes read, 0 seeks
 }}}

 What's odd, scaling to 35x44 produces correct image (with alpha plane).

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4926>
FFmpeg <https://ffmpeg.org>
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