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• FFMPEG - Scale video filter not providing expected results

  11 novembre 2011, par dpassera

  Apologies if this question has been asked. I couldn't find it, but if it has, please let me know and I'll close this out.

  I'm attempting a simple scale of a video whose original dimensions are 480x360 and whose target dimensions are 400x300. The video starts as an FLV and eventually needs to end up as an MPEG. I'm using the following command line to do this :

  ffmpeg -i user.flv -vf "scale=400:300" user_scaled.mpg

  When I play the scaled video in MPEG Streamclip, the scale is correct and the video info shows that the dimensions are 400x300. However, when I play the scaled video in Quicktime, the video is scaled to 478x359. More importantly, FFMPEG, itself, treats the video as being 478x359, so any future commands (trimming, conversion, overlaying, etc) executed on it result in a video of 478x359.

  The initial workflow required an FLV to MPEG conversion, but I've tried this with several different in and out formats (FLV -> FLV, FLV -> MPEG, MPEG -> MPEG, etc) all with the same results. As long as I can end up with an MPEG, though, I can deal with however many steps and conversions it would take to get this scaling working.

  I'll paste the command-line output below, and a sample input video is also linked below, if you'd like it. Thank you very much for any help.

  http://www.monkeydriver.com/dpassera/stack_flv.zip

  Command-line output :

  ffmpeg -i user.flv -vf "scale=400:300" user_scaled.mpg
  
  
  
  ffmpeg version 0.7-rc1, Copyright (c) 2000-2011 the FFmpeg developers
  
    built on May 21 2011 22:13:19 with gcc 4.1.2 20080704 (Red Hat 4.1.2-50)
  
    configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 
  
   --mandir=/usr/share/man --incdir=/usr/include --disable-avisynth
  
   --extra-cflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions
  
   -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -fPIC'
  
   --enable-avfilter --enable-libdirac --enable-libgsm --enable-libmp3lame
  
   --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libx264
  
   --enable-gpl --enable-postproc --enable-pthreads --enable-shared
  
   --enable-swscale --enable-vdpau --enable-version3 --enable-x11grab
  
   --disable-yasm --enable-filters --enable-filter=movie
  
  
  
    libavutil    50. 40. 1 / 50. 40. 1
  
    libavcodec   52.120. 0 / 52.120. 0
  
    libavformat  52.108. 0 / 52.108. 0
  
    libavdevice  52.  4. 0 / 52.  4. 0
  
    libavfilter   1. 77. 0 /  1. 77. 0
  
    libswscale    0. 13. 0 /  0. 13. 0
  
    libpostproc  51.  2. 0 / 51.  2. 0
  
  
  
  [flv @ 0x11dd3b30] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, flv, from 'user.flv':
  
  
  
    Metadata:
  
      duration        : 5
  
      videocodecid    : 2
  
      audiocodecid    : 6
  
      canSeekToEnd    : true
  
      createdby       : FMS 4.0
  
      creationdate    : Mon Oct 31 11:43:44 2011
  
  
  
    Duration: 00:00:04.62, start: 0.000000, bitrate: N/A
  
      Stream #0.0: Video: flv, yuv420p, 640x480, 1k tbr, 1k tbn, 1k tbc
  
      Stream #0.1: Audio: nellymoser, 44100 Hz, mono, s16
  
  
  
  [buffer @ 0x11ddc950] w:640 h:480 pixfmt:yuv420p
  
  
  
  [scale @ 0x11dda610] w:640 h:480 fmt:yuv420p -> w:400 h:300 fmt:yuv420p flags:0xa0000004
  
  
  
  [mpeg @ 0x11dd6bd0] VBV buffer size not set, muxing may fail
  
  
  
  Output #0, mpeg, to 'user_scaled.mpg':
  
    Metadata:
  
      duration        : 5
  
      videocodecid    : 2
  
      audiocodecid    : 6
  
      canSeekToEnd    : true
  
      createdby       : FMS 4.0
  
      creationdate    : Mon Oct 31 11:43:44 2011
  
      encoder         : Lavf52.108.0
  
  
  
      Stream #0.0: Video: mpeg1video, yuv420p, 400x300, q=2-31, 200 kb/s, 90k tbn, 60 tbc
  
  
  
      Stream #0.1: Audio: mp2, 44100 Hz, mono, s16, 64 kb/s
  
  
  
  Stream mapping:
  
  Stream #0.0 -> #0.0
  
  Stream #0.1 -> #0.1
  
  
  
  Press [q] to stop encoding
  
  frame=  230 fps=  0 q=10.2 size=     366kB time=3.82 bitrate= 785.6kbits/s dup=175 drop=0 
  
  frame=  267 fps=  0 q=10.7 Lsize=     412kB time=4.43 bitrate= 761.3kbits/s dup=203 drop=0    
  
  
  
  video:370kB audio:36kB global headers:0kB muxing overhead 1.568959%

• Increase maximum encoding video buffer size.

  14 janvier 2012, par Carl Eugen Hoyos

  Increase maximum encoding video buffer size.

• ffmpeg c api for cutting video

  13 janvier 2012, par user1148080

  first thing sorry for my bad english, i'm making an android app that need to get part of a video, the idea is i need a method that get input a video file, start-time, end-time then cutting video from star-time to end-time and output to a new file, i get ffmpeg for android from http://bambuser.com/opensource and able to compile it, integrate with JNI, but now i dont know which ffmpeg's api to use for do the thing a need, any help, example are much appreciated.