Recherche avancée

Sur d’autres sites (11133)

• Encode video of powerpoint presentation for HTML5 playback

  17 avril 2013, par user2291446

  We have a number of powerpoint presentations that have been converted to 16:9
  aspect ratio and then converted into mp4 "master videos" with an "apple TV" 720p
  profile. These powerpoint presentations are voice annotated. So in essence, we
  show a slide and then let the annotation sound play for a while, then go to the
  next slide, and so on. The resulting mp4 master video is somewhere around 900MB
  on average.

  Here is an example of the master video

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4' :
  Metadata :
      major_brand : isom
      minor_version : 512
      compatible_brands : isomiso2avc1mp41
      creation_time : 1970-01-01 00:00:00
      encoder : Lavf52.104.0
    Duration : 02:00:57.65, start : 0.000000, bitrate : 970 kb/s
      Stream #0:0(und) : Video : h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 836 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc
      Metadata :
        creation_time : 1970-01-01 00:00:00
        handler_name : VideoHandler
      Stream #0:1(und) : Audio : aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s
      Metadata :
        creation_time : 1970-01-01 00:00:00
        handler_name : SoundHandler
  

  We are trying to get these presentations to play on the web on as many
  devices/browsers as possible including some that don't do HTML5 (IE7/IE8). We
  have narrowed down our player of choice which is mediaElement and have extracted
  some "cue points" from the powerpoint presentation that mark where the slides
  are changing. We have also captured thumbnails for those cuepoints such that we
  now have a nice list of thumbnails for each slide and an associated cuepoint in
  the video where the particular slide begins.

  Here comes the problem...due to the large size of the master video it is not
  practical for us to use the master video with our mediaElement player. We do
  need to transcode the master video to mp4 and ogv in order to get decent
  device/browser coverage.

  We do not seem to be able to find a suitable transcoding strategy to reduce the
  size of the video. We have played with numerous ffmpeg settings and were able to
  reduce the size but when we do so we compromise the ability to jump to specific
  cue points.

  It works well for browsers that do HTML5 video natively (Chrome and Firefox) but
  not for the flash fallback of mediaElement (IE7/IE8) which uses the mp4 file and
  seemingly is very tied to the number and frequency of key frames in the video in
  order to allow for clean seeking and skipping using the cue points.

  Seeing that we are talking about a video that has only slides (practically 90
  static images per presentation) and some sound we imagine it must be possible to
  transcode as such that the keyframes fall at the cue points or near the
  cuepoints, and that the size of the video could be drastically reduced while
  still allowing for smooth seeking and skipping.

• ffmpeg converts .flv video to .gif with awful quality [migrated]

  22 février 2013, par Kamil Hismatullin

  I'm converting .flv movie to .gif file with ffmpeg.

  ffmpeg -i input.flv -ss 00:00:00.000 -pix_fmt rgb24 -r 10 -s 320x240 -t 00:00:10.000  output.gif

  It works great, but output gif file has a very law quality.

  Any ideas how can I improve quality of converted gif ?

  Output of command :

  $ ffmpeg -i input.flv -ss 00:00:00.000 -pix_fmt rgb24 -r 10 -s 320x240 -t 00:00:10.000  output.gif 
  
  
  
  ffmpeg version 0.8.5-6:0.8.5-0ubuntu0.12.10.1, Copyright (c) 2000-2012 the Libav developers
  
    built on Jan 24 2013 14:52:53 with gcc 4.7.2
  
  *** THIS PROGRAM IS DEPRECATED ***
  
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.flv':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2013-02-14 04:00:07
  
    Duration: 00:00:18.85, start: 0.000000, bitrate: 3098 kb/s
  
      Stream #0.0(und): Video: h264 (High), yuv420p, 1280x720, 2905 kb/s, 25 fps, 25 tbr, 50 tbn, 50 tbc
  
      Metadata:
  
        creation_time   : 1970-01-01 00:00:00
  
      Stream #0.1(und): Audio: aac, 44100 Hz, stereo, s16, 192 kb/s
  
      Metadata:
  
        creation_time   : 2013-02-14 04:00:07
  
  [buffer @ 0x92a8ea0] w:1280 h:720 pixfmt:yuv420p
  
  [scale @ 0x9215100] w:1280 h:720 fmt:yuv420p -> w:320 h:240 fmt:rgb24 flags:0x4
  
  Output #0, gif, to 'output.gif':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2013-02-14 04:00:07
  
      encoder         : Lavf53.21.1
  
      Stream #0.0(und): Video: rawvideo, rgb24, 320x240, q=2-31, 200 kb/s, 90k tbn, 10 tbc
  
      Metadata:
  
        creation_time   : 1970-01-01 00:00:00
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press ctrl-c to stop encoding
  
  frame=  101 fps= 32 q=0.0 Lsize=    8686kB time=10.10 bitrate=7045.0kbits/s dup=0 drop=149    
  
  video:22725kB audio:0kB global headers:0kB muxing overhead -61.778676%

  Thanks.

• ffmpeg to convert mov to flv

  27 octobre 2014, par jeet

  I’m trying to convert a mov video to flv, but keep getting these errors below.
  There are 2 commands I used, both are below.

  ffmpeg -y -i video.mov -deinterlace -acodec copy -r 25 -qmin 3 -qmax 6 video.flv
  
  
  
  
  
  FFmpeg version SVN-r16573, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  
  configuration: --extra-cflags=-fno-common --enable-memalign-hack --enable-pthreads --enable-libmp3lame --enable-libxvid --enable-libvorbis --enable-libtheora --enable-libspeex --enable-libfaac --enable-libgsm --enable-libx264 --enable-libschroedinger --enable-avisynth --enable-swscale --enable-gpl
  
  libavutil     49.12. 0 / 49.12. 0
  
  libavcodec    52.10. 0 / 52.10. 0
  
  libavformat   52.23. 1 / 52.23. 1
  
  libavdevice   52. 1. 0 / 52. 1. 0
  
  libswscale     0. 6. 1 /  0. 6. 1
  
  built on Jan 13 2009 02:57:09, gcc: 4.2.4
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'vid\video.mov':
  
  Duration: 00:03:16.00, start: 0.000000, bitrate: 398 kb/s
  
  Stream #0.0(eng): Video: mpeg4, yuv420p, 800x600 [PAR 1:1 DAR 4:3], 30.00 tb(r)
  
  Stream #0.1(eng): Audio: pcm_u8, 8000 Hz, mono, s16, 64 kb/s
  
  Output #0, flv, to 'vid\video.flv':
  
  Stream #0.0(eng): Video: flv, yuv420p, 800x600 [PAR 1:1 DAR 4:3], q=3-6, 200 kb/s, 25.00 tb(c)
  
  Stream #0.1(eng): Audio: pcm_u8, 8000 Hz, mono, s16, 64 kb/s
  
  Stream mapping:
  
  Stream #0.0 -> #0.0
  
  Stream #0.1 -> #0.1
  
  [NULL @ 0x1714390]codec not compatible with flv
  
  Could not write header for output file #0 (incorrect codec parameters ?)

  Second command :

  ffmpeg -y -i video.mov -deinterlace -ar 44100 -r 25 -qmin 3 -qmax 6 video.flv

  Audio resampler only works with 16 bits per sample, patch welcome.

  With a newer version of ffmpeg :

  ffmpeg version N-49610-gc2dd5a1 Copyright (c) 2000-2013 the FFmpeg developers
  
  built on Feb  5 2013 13:20:59 with gcc 4.7.2 (GCC)
  
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  
    libavutil      52. 17.101 / 52. 17.101
  
    libavcodec     54. 91.100 / 54. 91.100
  
    libavformat    54. 61.104 / 54. 61.104
  
    libavdevice    54.  3.103 / 54.  3.103
  
    libavfilter     3. 35.101 /  3. 35.101
  
    libswscale      2.  2.100 /  2.  2.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  2.100 / 52.  2.100
  
  Guessed Channel Layout for  Input Stream #0.1 : mono
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'vid\video.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 512
  
      compatible_brands: qt  
  
      creation_time   : 1970-01-01 00:00:00
  
    Duration: 00:02:50.39, start: 0.000000, bitrate: 370 kb/s
  
      Stream #0:0(eng): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 1366x768 [SAR 1:1 DAR 683:384], 308 kb/s, 11.50 fps, 11.50 tbr, 23 tbn, 23 tbc
  
      Metadata:
  
        creation_time   : 1970-01-01 00:00:00
  
        handler_name    : DataHandler
  
      Stream #0:1(eng): Audio: pcm_u8 (raw  / 0x20776172), 8000 Hz, mono, u8, 64 kb/s
  
      Metadata:
  
        creation_time   : 1970-01-01 00:00:00
  
        handler_name    : DataHandler
  
  [flv @ 026347a0] FLV does not support sample rate 8000, choose from (44100, 22050, 11025)
  
  Output #0, flv, to 'vid\video.flv':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 512
  
  compatible_brands: qt  
  
      encoder         : Lavf54.61.104
  
      Stream #0:0(eng): Video: flv1 ([2][0][0][0] / 0x0002), yuv420p, 1366x768 [SAR 1:1 DAR 683:384], q=2-31, 200 kb/s, 1k tbn, 11.50 tbc
  
      Metadata:
  
        creation_time   : 1970-01-01 00:00:00
  
        handler_name    : DataHandler
  
      Stream #0:1(eng): Audio: mp3 ([2][0][0][0] / 0x0002), 8000 Hz, mono, s16p
  
      Metadata:
  
        creation_time   : 1970-01-01 00:00:00
  
        handler_name    : DataHandler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mpeg4 -> flv)
  
    Stream #0:1 -> #0:1 (pcm_u8 -> libmp3lame)
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid data found when processing input

  1 more thing please :
  If I use this newer version of ffmpeg to create a video with the below command, I get a video with a very hazy display.
  It’s like a few black dots on a blank screen :

  ffmpeg -i img%d.png -i audio.wav -acodec copy output.mov

  what could be the reason for this display ?