[FFmpeg-trac] #5622(undetermined:new): Image overlay with straight alpha

[FFmpeg]

#5622: Image overlay with straight alpha
-------------------------------------+-------------------------------------
             Reporter:  jb_alvarado  |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 I have here png images with an alpha, rendered by Blackmagic Fusion. When
 I overly them on top of a video, I get dark boarders around the color.

 ffmpeg command:
 {{{
 ffmpeg -i "video.mp4" -i straight_alpha0001.png -filter_complex
 "[0:v][1:v]overlay[out]" -map '[out]' -f opengl "test"
 }}}

 ffmpeg output:
 {{{
 ffmpeg version git-2016-04-27-a2ba50b Copyright (c) 2000-2016 the FFmpeg
 developers
   built with Apple LLVM version 7.3.0 (clang-703.0.29)
   configuration: --arch=x86_64 --prefix=/Users/jb_/dev/compileTools/local
 --disable-debug --disable-shared --disable-doc --enable-gpl --enable-
 version3 --enable-runtime-cpudetect --enable-avfilter --enable-fontconfig
 --enable-libfreetype --enable-libmp3lame --enable-opengl --enable-libvpx
 --enable-libx264 --enable-libx265 --enable-decklink --extra-
 cflags='-I$LOCALDESTDIR/include/decklink' --extra-
 ldflags='-L$LOCALDESTDIR/include/decklink' --extra-
 cflags=-DLIBTWOLAME_STATIC --extra-libs='-lxml2 -llzma -lstdc++ -lpng -lm
 -lexpat -liconv' pkg_config='pkg-config --static'
   libavutil      55. 22.101 / 55. 22.101
   libavcodec     57. 38.100 / 57. 38.100
   libavformat    57. 34.103 / 57. 34.103
   libavdevice    57.  0.101 / 57.  0.101
   libavfilter     6. 44.100 /  6. 44.100
   libswscale      4.  1.100 /  4.  1.100
   libswresample   2.  0.101 /  2.  0.101
   libpostproc    54.  0.100 / 54.  0.100
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4':
   Metadata:
     major_brand     : mp42
     minor_version   : 0
     compatible_brands: isomiso2avc1mp41mp42
     encoder         : Lavf57.21.101
   Duration: 01:07:46.05, start: 0.000000, bitrate: 1789 kb/s
     Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p,
 1024x576 [SAR 1:1 DAR 16:9], 1511 kb/s, 25 fps, 25 tbr, 12800 tbn
 (default)
     Metadata:
       handler_name    : VideoHandler
     Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
 stereo, fltp, 192 kb/s (default)
     Metadata:
       handler_name    : SoundHandler
     Stream #0:2(und): Data: none (rtp  / 0x20707472), 68 kb/s (default)
     Metadata:
       creation_time   : 2016-02-26 14:01:33
       handler_name    : GPAC ISO Hint Handler
     Stream #0:3(und): Data: none (rtp  / 0x20707472), 11 kb/s (default)
     Metadata:
       creation_time   : 2016-02-26 14:01:34
       handler_name    : GPAC ISO Hint Handler
 Input #1, png_pipe, from
 '/Volumes/dev/scripts/shellScripts/snips/straight_alpha0004.png':
   Duration: N/A, bitrate: N/A
     Stream #1:0: Video: png, rgba(pc), 300x300, 25 tbr, 25 tbn
 [opengl @ 0x7fab4c800000] Using AVStream.codec to pass codec parameters to
 muxers is deprecated, use AVStream.codecpar instead.
 [opengl outdev @ 0x7fab4c100160] SDL driver: 'Quartz'.
 Output #0, opengl, to 'test':
   Metadata:
     major_brand     : mp42
     minor_version   : 0
     compatible_brands: isomiso2avc1mp41mp42
     encoder         : Lavf57.34.103
     Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 1024x576
 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 25 tbn (default)
     Metadata:
       encoder         : Lavc57.38.100 rawvideo
 Stream mapping:
   Stream #0:0 (h264) -> overlay:main
   Stream #1:0 (png) -> overlay:overlay
   overlay -> Stream #0:0 (rawvideo)
 Press [q] to stop, [?] for help
 frame=  396 fps= 60 q=-0.0 Lsize=N/A time=00:00:15.92 bitrate=N/A speed=
 2.4x
 video:342144kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: unknown
 }}}

 Theoretical I could fix this with an expression like:

 r/a, g/a, b/a, a

 But I don't found any way to apply this.

 Regards

 Jonathan

--
Ticket URL: <https://trac.ffmpeg.org/ticket/5622>
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