[FFmpeg-trac] #814(undetermined:new): rgb24 -> yuv420p conversion is not precise?

FFmpeg trac at avcodec.org
Wed Dec 21 19:24:51 CET 2011


#814: rgb24 -> yuv420p conversion is not precise?
-------------------------------------+-------------------------------------
             Reporter:  ami_stuff    |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 I don't know if this is a bug (or it should be like it is), but when you
 convert the attached rgb24 sample to yuv420p then for example the red line
 in the picture will be not smooth anymore

 {{{
 C:\>ffmpeg -i tetest.tif -pix_fmt yuv420p out.tif
 ffmpeg version N-35966-g1d0ae92, Copyright (c) 2000-2011 the FFmpeg
 developers
   built on Dec 19 2011 13:01:15 with gcc 4.6.2
   configuration: --enable-gpl --enable-version3 --disable-w32threads
 --enable-ru
 ntime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-
 libope
 ncore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-
 libgsm --en
 able-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-
 libschroedinger -
 -enable-libspeex --enable-libtheora --enable-libvo-aacenc --enable-libvo-
 amrwben
 c --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs
 --enable-
 libxvid --enable-zlib
   libavutil    51. 32. 0 / 51. 32. 0
   libavcodec   53. 46. 1 / 53. 46. 1
   libavformat  53. 27. 0 / 53. 27. 0
   libavdevice  53.  4. 0 / 53.  4. 0
   libavfilter   2. 53. 0 /  2. 53. 0
   libswscale    2.  1. 0 /  2.  1. 0
   libpostproc  51.  2. 0 / 51.  2. 0
 Input #0, image2, from 'tetest.tif':
   Duration: 00:00:00.04, start: 0.000000, bitrate: N/A
     Stream #0:0: Video: tiff, rgb24, 1024x768, 25 tbr, 25 tbn, 25 tbc
 [buffer @ 020E1200] w:1024 h:768 pixfmt:rgb24 tb:1/1000000 sar:0/1
 sws_param:
 [buffersink @ 020E1480] auto-inserting filter 'auto-inserted scale 0'
 between th
 e filter 'src' and the filter 'out'
 [scale @ 020E1880] w:1024 h:768 fmt:rgb24 -> w:1024 h:768 fmt:yuv420p
 flags:0x4
 Output #0, image2, to 'out.tif':
   Metadata:
     encoder         : Lavf53.27.0
     Stream #0:0: Video: tiff, yuv420p, 1024x768, q=2-31, 200 kb/s, 90k
 tbn, 25 t
 bc
 Stream mapping:
   Stream #0:0 -> #0:0 (tiff -> tiff)
 Press [q] to stop, [?] for help
 frame=    1 fps=  0 q=0.0 Lsize=       0kB time=00:00:00.04 bitrate=
 0.0kbits/
 s
 video:1158kB audio:0kB global headers:0kB muxing overhead -100.000000%
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/814>
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