[FFmpeg-user] ffplay at half size by means of a math function

[Jim Shupert, Jr.]

Friends,

I wish to be able to play a file with ffplay but have it play at 1/2 the
real size

with -x NUM  -y NUM
I can control play size with
ffplay -x 640 -y 360 -i dog.avi
this works as hoped

but what I would really like to do is do some math on the file and scale
it down


with something like
ffplay -vf=scale=iw/2:ih/2 -i /media/data/zzz-s/NASA_logo.mov

my Goal is to have a means of scaling down 1080p  to a size that fits
nicely on my vga

 ffplay -vf=scale=iw/2:ih/2 -i /media/data/zzz-s/NASA_logo.mov
ffplay version git-2013-10-16-586b8ea Copyright (c) 2003-2013 the FFmpeg
developers
  built on Oct 16 2013 13:38:00 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --prefix=/home/j/ffmpeg_build
--extra-cflags=-I/home/j/ffmpeg_build/include
--extra-ldflags=-L/home/j/ffmpeg_build/lib --bindir=/home/j/bin
--extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac
--enable-libmp3lame --enable-libopus --enable-libtheora
--enable-libvorbis --enable-libvpx --enable-libfreetype --enable-libx264
--enable-nonfree --enable-x11grab
  libavutil      52. 46.101 / 52. 46.101
  libavcodec     55. 37.100 / 55. 37.100
  libavformat    55. 19.102 / 55. 19.102
  libavdevice    55.  4.100 / 55.  4.100
  libavfilter     3. 88.101 /  3. 88.101
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.103 /  0. 17.103
  libpostproc    52.  3.100 / 52.  3.100
Failed to set value '-i' for option 'vf=scale=iw/2:ih/2': Option not found



with video_size

 ffplay -video_size 320x240-i /media/data/zzz-s/NASA_logo.mov
ffplay version git-2013-10-16-586b8ea Copyright (c) 2003-2013 the FFmpeg
developers
  built on Oct 16 2013 13:38:00 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --prefix=/home/j/ffmpeg_build
--extra-cflags=-I/home/j/ffmpeg_build/include
--extra-ldflags=-L/home/j/ffmpeg_build/lib --bindir=/home/j/bin
--extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac
--enable-libmp3lame --enable-libopus --enable-libtheora
--enable-libvorbis --enable-libvpx --enable-libfreetype --enable-libx264
--enable-nonfree --enable-x11grab
  libavutil      52. 46.101 / 52. 46.101
  libavcodec     55. 37.100 / 55. 37.100
  libavformat    55. 19.102 / 55. 19.102
  libavdevice    55.  4.100 / 55.  4.100
  libavfilter     3. 88.101 /  3. 88.101
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.103 /  0. 17.103
  libpostproc    52.  3.100 / 52.  3.100
Option video_size not found.aq=    0KB vq=    0KB sq=    0B f=0/0


Thanks

jim S