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• Convert FLV video with alpha channel to PNGs with transparency

  8 octobre 2012, par AZAR

  I have some FLV videos with alpha channels, and I want to convert each of them to PNG images using ffmpeg but keep the transparency.

  So far, I've tried this :

  ffmpeg -i input.flv -an -y %d.png

  But this outputs the PNG files with black background.

  Is there any way to do this ?

  Alternate acceptable solution : If I can output the images and give the alpha channel a certain color of my choice. I can then remove it later via imagemagick and convert that color to transparency.

• .mov conversion to .mp4 using ffmpeg doesn't convert the entire video

  5 février 2013, par user504879

  I am trying to convert a mov file which I got from saving my powerpoint presentation to a movie file. However only a part of the presentation is converted not the entire one and also running qt-start doesn't make the exported mp4 to stream over rtmp. Is there something which I am missing ?

  I am attaching the output which i get when I am trying to convert the file using ffmpeg

  $ export LD_LIBRARY_PATH=/usr/local/lib; /usr/local/bin/ffmpeg -y -i /data/tmp/vialogues_prez.mov -r 20 -g 40 -acodec libfaac -ar 44100  -ab 96k -vcodec libx264 -s 640x480 -vpre medium /data/videos/vialogues_prez.mp4
  
  
  
  FFmpeg version 0.6.1, Copyright (c) 2000-2010 the FFmpeg developers
  
    built on Feb 19 2011 19:03:56 with gcc 4.4.5
  
    configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-x11grab
  
    libavutil     50.15. 1 / 50.15. 1
  
    libavcodec    52.72. 2 / 52.72. 2
  
    libavformat   52.64. 2 / 52.64. 2
  
    libavdevice   52. 2. 0 / 52. 2. 0
  
    libswscale     0.11. 0 /  0.11. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x186f460]max_analyze_duration reached
  
  
  
  Seems stream 0 codec frame rate differs from container frame rate: 600.00 (600/1) -> 0.08 (1/12)
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/data/tmp/vialogues_prez.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      comment         : Microsoft PowerPoint Movie
  
      comment-eng     : Microsoft PowerPoint Movie
  
    Duration: 00:04:47.00, start: 0.000000, bitrate: 22 kb/s
  
      Stream #0.0(eng): Video: qtrle, bgra, 640x480, 21 kb/s, 0.01 fps, 0.08 tbr, 600 tbn, 600 tbc
  
      Stream #0.1(eng): Video: 0x0000, 600 tbr, 600 tbn, 600 tbc
  
      Stream #0.2(eng): Video: 0x0000, 600 tbr, 600 tbn, 600 tbc
  
  [libx264 @ 0x1873b50]using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.1 Cache64
  
  [libx264 @ 0x1873b50]profile High, level 3.0
  
  [libx264 @ 0x1873b50]264 - core 114 - H.264/MPEG-4 AVC codec - Copyleft 2003-2011 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=abr mbtree=1 bitrate=200 ratetol=20.0 qcomp=0.60 qpmin=10 qpmax=51 qpstep=4 ip_ratio=1.41 aq=1:1.00
  
  Output #0, mp4, to '/data/videos/vialogues_prez.mp4':
  
    Metadata:
  
      encoder         : Lavf52.64.2
  
      Stream #0.0(eng): Video: libx264, yuv420p, 640x480, q=10-51, 200 kb/s, 20 tbn, 20 tbc
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press [q] to stop encoding
  
  frame=    4 fps=  0 q=32766.0 Lsize=      50kB time=45.05 bitrate=   9.0kbits/s    
  
  video:49kB audio:0kB global headers:0kB muxing overhead 1.740573%
  
  [libx264 @ 0x1873b50]frame I:1     Avg QP:32.73  size:  8427
  
  [libx264 @ 0x1873b50]frame P:3     Avg QP:20.68  size: 13640
  
  [libx264 @ 0x1873b50]mb I  I16..4: 60.8% 14.6% 24.7%
  
  [libx264 @ 0x1873b50]mb P  I16..4: 28.7%  7.2% 15.4%  P16..4:  2.0%  1.3%  1.4%  0.0%  0.0%    skip:43.9%
  
  [libx264 @ 0x1873b50]final ratefactor: -16.67
  
  [libx264 @ 0x1873b50]8x8 transform intra:14.2% inter:5.0%
  
  [libx264 @ 0x1873b50]coded y,uvDC,uvAC intra: 25.2% 18.4% 13.0% inter: 5.3% 7.4% 7.2%
  
  [libx264 @ 0x1873b50]i16 v,h,dc,p: 63% 34%  1%  2%
  
  [libx264 @ 0x1873b50]i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 19% 41% 31%  1%  1%  1%  1%  1%  4%
  
  [libx264 @ 0x1873b50]i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 29% 33% 19%  2%  3%  3%  4%  3%  4%
  
  [libx264 @ 0x1873b50]i8c dc,h,v,p: 75% 20%  4%  1%
  
  [libx264 @ 0x1873b50]Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264 @ 0x1873b50]ref P L0: 57.0% 12.2% 26.2%  4.7%
  
  [libx264 @ 0x1873b50]kb/s:1.14

  any help is appreciated.

• How do I reduce the video size captured by the default camera using FFMPEG in Android ?

  12 octobre 2011, par Krishnendu

  I am trying to reduce the video size captured by the default camera (it's generating high resolution video) in Android. Does FFMPEG have a property to encode a video with given resolution ? I tried to Google, but all examples are using command line mode for FFMPEG.

  My questions are :

  1. Can we use ffmpeg command line in Android ?
  2. If not then how we will achieve it ?
  3. Can we able record a video directly using ffmpeg in Android ?
  4. Is there any other solution for this ?