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  • Keeping control of your media in your hands

    13 avril 2011, par

    The vocabulary used on this site and around MediaSPIP in general, aims to avoid reference to Web 2.0 and the companies that profit from media-sharing.
    While using MediaSPIP, you are invited to avoid using words like "Brand", "Cloud" and "Market".
    MediaSPIP is designed to facilitate the sharing of creative media online, while allowing authors to retain complete control of their work.
    MediaSPIP aims to be accessible to as many people as possible and development is based on expanding the (...)

  • Use, discuss, criticize

    13 avril 2011, par

    Talk to people directly involved in MediaSPIP’s development, or to people around you who could use MediaSPIP to share, enhance or develop their creative projects.
    The bigger the community, the more MediaSPIP’s potential will be explored and the faster the software will evolve.
    A discussion list is available for all exchanges between users.

  • Installation en mode ferme

    4 février 2011, par

    Le mode ferme permet d’héberger plusieurs sites de type MediaSPIP en n’installant qu’une seule fois son noyau fonctionnel.
    C’est la méthode que nous utilisons sur cette même plateforme.
    L’utilisation en mode ferme nécessite de connaïtre un peu le mécanisme de SPIP contrairement à la version standalone qui ne nécessite pas réellement de connaissances spécifique puisque l’espace privé habituel de SPIP n’est plus utilisé.
    Dans un premier temps, vous devez avoir installé les mêmes fichiers que l’installation (...)

Sur d’autres sites (5803)

  • Revision 107161 : A priori la différence (qui fait des scrolls étonnants sur Spip ...

    25 octobre 2017, par marcimat@… — Log

    A priori la différence (qui fait des scrolls étonnants sur Spip Contrib) vient du fait que la nouvelle version
    de la librairie scroll automatiquement au chargement alors que ce n’était pas ce comportement auparavant.
    Et le scroll automatique ne tient pas compte du fait de savoir si l’ancre désirée est déjà visible ou non,
    et scoll du haut de la page vers l’ancre (même si on était déjà sur l’ancre !).
    Du coup, on annule ce scroll automatique au chargement.

  • difference between Alien-ffmpeg and ffmpeg

    15 octobre 2018, par jsor

    I want to record a video with perl i found the following 2 modules on cpan :

    Alien-ffmpeg (https://metacpan.org/pod/release/GETTY/Alien-ffmpeg-0.103/lib/Alien/ffmpeg.pm ) and ffmpeg https://metacpan.org/pod/FFmpeg

    what is the difference between those 2 modules , i see the Alien module don’t have a documentaiton but its more up to date than ffmpeg module , how can i use it ?

    are there also other recommeneded perl modules how to record mp4 file with Perl ?

  • Video frame difference with FFMPEG

    18 octobre 2018, par StepTNT

    I need to compute the frame differences between a source video and a compressed one.
    For now I’m using OpenCV with Java, by extracting each frame and doing a simple difference, but it’s quite slow (working a 0.5 fps, meaning that a 500 frames video will take more than 15 mins) so I was thinking to move to FFMPEG.

    FFMPEG feels a lot faster (everything’s done under 1 minute) but it has one big issue that makes the results useless : when compressing the source file, done with FFMPEG too, an extra gray frame is added at the beginning and this fakes the results because different frames are compared.

    This is what I’m doing now (knowing that the extra frame messes it all) :

    ffmpeg -y -i src.avi -i compressed.avi -filter_complex "blend=all_mode=difference,hue=s=0" -c:v libx264 -crf 18 -c:a copy difference.avi

    To fix the frame issue I was trying to remove the first frame by re-encoding the compressed video with this command

    ffmpeg -y -ss 0.02 -i compressed.mpg -an -f mpeg2video compressed-cut.mpg"

    (Note that -ss is 0.02 because it’s a 50 fps video, so I did 1/FPS as suggested here)

    But I get this response

    Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)

    So, finally, the question is : since extracting all the frames and then compute differences with OpenCV is really slow, how can I use FFMPEG to produce a video containing the difference between two sources while keeping in mind that one of them has an extra frame at the beginning ?

    EDIT : I wanted to avoid posting endless console outputs but since you asked for it, here we go.

    1) Encoding

    Input

    ffmpeg -i "720p50_mobcal_ter.avi" -an -f mpeg2video -y "720p50_mobcal_ter.mpg"

    Output

    ffmpeg version N-76684-g1fe82ab Copyright (c) 2000-2015 the FFmpeg developers
    
  built with gcc 5.2.0 (GCC)
    
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --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-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
    
  libavutil      55.  6.100 / 55.  6.100
    
  libavcodec     57. 15.100 / 57. 15.100
    
  libavformat    57. 14.100 / 57. 14.100
    
  libavdevice    57.  0.100 / 57.  0.100
    
  libavfilter     6. 15.100 /  6. 15.100
    
  libswscale      4.  0.100 /  4.  0.100
    
  libswresample   2.  0.101 /  2.  0.101
    
  libpostproc    54.  0.100 / 54.  0.100
    
Input #0, avi, from '720p50_mobcal_ter.avi':
    
  Metadata:
    
    encoder         : Lavf57.14.100
    
  Duration: 00:00:10.08, start: 0.000000, bitrate: 552974 kb/s
    
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 1280x720, 554059 kb/s, SAR 1:1 DAR 16:9, 50 fps, 50 tbr, 50 tbn, 50 tbc
    
Output #0, mpeg2video, to '720p50_mobcal_ter.mpg':
    
  Metadata:
    
    encoder         : Lavf57.14.100
    
    Stream #0:0: Video: mpeg2video, yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 50 fps, 50 tbn, 50 tbc
    
    Metadata:
    
      encoder         : Lavc57.15.100 mpeg2video
    
Stream mapping:
    
  Stream #0:0 -> #0:0 (rawvideo (native) -> mpeg2video (native))
    
Press [q] to stop, [?] for help
    
frame=   41 fps=0.0 q=31.0 size=     984kB time=00:00:00.78 bitrate=10330.5kbits/frame=   80 fps= 78 q=31.0 size=    1323kB time=00:00:01.56 bitrate=6948.1kbits/frame=  124 fps= 80 q=31.0 size=    1725kB time=00:00:02.44 bitrate=5790.0kbits/frame=  168 fps= 81 q=31.0 size=    2084kB time=00:00:03.32 bitrate=5142.8kbits/frame=  212 fps= 81 q=31.0 size=    2482kB time=00:00:04.20 bitrate=4841.4kbits/frame=  255 fps= 82 q=31.0 size=    2840kB time=00:00:05.06 bitrate=4597.2kbits/frame=  296 fps= 82 q=31.0 size=    3133kB time=00:00:05.88 bitrate=4364.5kbits/frame=  338 fps= 82 q=24.8 size=    3453kB time=00:00:06.72 bitrate=4209.2kbits/frame=  382 fps= 82 q=31.0 size=    3723kB time=00:00:07.60 bitrate=4013.4kbits/frame=  426 fps= 83 q=31.0 size=    4005kB time=00:00:08.48 bitrate=3869.1kbits/frame=  470 fps= 83 q=24.8 size=    4276kB time=00:00:09.36 bitrate=3742.5kbits/frame=  504 fps= 83 q=31.0 Lsize=    4469kB time=00:00:10.06 bitrate=3639.3kbits/s
    
video:4469kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%

    This adds the extra grey frame at the beginning, it just duplicates the first one

    2) Removing first frame

    Input

    ffmpeg -y -i "720p50_mobcal_ter.mpg" -an -f mpeg2video -vf select=gte(n\,1) "CUT-720p50_mobcal_ter.mpg"

    Output

    ffmpeg version N-76684-g1fe82ab Copyright (c) 2000-2015 the FFmpeg developers
    
  built with gcc 5.2.0 (GCC)
    
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --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-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
    
  libavutil      55.  6.100 / 55.  6.100
    
  libavcodec     57. 15.100 / 57. 15.100
    
  libavformat    57. 14.100 / 57. 14.100
    
  libavdevice    57.  0.100 / 57.  0.100
    
  libavfilter     6. 15.100 /  6. 15.100
    
  libswscale      4.  0.100 /  4.  0.100
    
  libswresample   2.  0.101 /  2.  0.101
    
  libpostproc    54.  0.100 / 54.  0.100
    
Input #0, mpegvideo, from '720p50_mobcal_ter.mpg':
    
  Duration: N/A, bitrate: N/A
    
    Stream #0:0: Video: mpeg2video (Main), yuv420p(tv), 1280x720 [SAR 1:1 DAR 16:9], max. 104857 kb/s, 50 fps, 50 tbr, 1200k tbn, 100 tbc
    
Output #0, mpeg2video, to 'CUT-720p50_mobcal_ter.mpg':
    
  Metadata:
    
    encoder         : Lavf57.14.100
    
    Stream #0:0: Video: mpeg2video, yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 50 fps, 50 tbn, 50 tbc
    
    Metadata:
    
      encoder         : Lavc57.15.100 mpeg2video
    
Stream mapping:
    
  Stream #0:0 -> #0:0 (mpeg2video (native) -> mpeg2video (native))
    
Press [q] to stop, [?] for help
    
frame=  255 fps=0.0 q=31.0 size=    2781kB time=00:00:05.10 bitrate=4467.3kbits/frame=  503 fps=0.0 q=31.0 Lsize=    4415kB time=00:00:10.08 bitrate=3588.5kbits/s
    
video:4415kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%

    3) Frame difference

    Input

    ffmpeg -y -i "720p50_mobcal_ter.avi" -i "CUT-720p50_mobcal_ter.mpg" -filter_complex "blend=all_mode=difference,hue=s=0" -c:v libx264 -crf 18 -c:a copy "DIFF-720p50_mobcal_ter.mpg"

    Output

    ffmpeg version N-76684-g1fe82ab Copyright (c) 2000-2015 the FFmpeg developers
    
  built with gcc 5.2.0 (GCC)
    
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --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-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
    
  libavutil      55.  6.100 / 55.  6.100
    
  libavcodec     57. 15.100 / 57. 15.100
    
  libavformat    57. 14.100 / 57. 14.100
    
  libavdevice    57.  0.100 / 57.  0.100
    
  libavfilter     6. 15.100 /  6. 15.100
    
  libswscale      4.  0.100 /  4.  0.100
    
  libswresample   2.  0.101 /  2.  0.101
    
  libpostproc    54.  0.100 / 54.  0.100
    
Input #0, avi, from '720p50_mobcal_ter.avi':
    
  Metadata:
    
    encoder         : Lavf57.14.100
    
  Duration: 00:00:10.08, start: 0.000000, bitrate: 552974 kb/s
    
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 1280x720, 554059 kb/s, SAR 1:1 DAR 16:9, 50 fps, 50 tbr, 50 tbn, 50 tbc
    
Input #1, mpegvideo, from 'CUT-720p50_mobcal_ter.mpg':
    
  Duration: N/A, bitrate: N/A
    
    Stream #1:0: Video: mpeg2video (Main), yuv420p(tv), 1280x720 [SAR 1:1 DAR 16:9], max. 104857 kb/s, 50 fps, 50 tbr, 1200k tbn, 100 tbc
    
[libx264 @ 000002784dbeb980] using SAR=1/1
    
[libx264 @ 000002784dbeb980] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
    
[libx264 @ 000002784dbeb980] profile High, level 3.2
    
[mpeg @ 000002784dbeaf20] VBV buffer size not set, using default size of 130KB
    
If you want the mpeg file to be compliant to some specification
    
Like DVD, VCD or others, make sure you set the correct buffer size
    
Output #0, mpeg, to 'D:\DOWNLOADS\TMP\Video TDI\AVI\DIFF-720p50_mobcal_ter.mpg':
    
  Metadata:
    
    encoder         : Lavf57.14.100
    
    Stream #0:0: Video: h264 (libx264), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 50 fps, 90k tbn, 50 tbc (default)
    
    Metadata:
    
      encoder         : Lavc57.15.100 libx264
    
Stream mapping:
    
  Stream #0:0 (rawvideo) -> blend:top
    
  Stream #1:0 (mpeg2video) -> blend:bottom
    
  hue -> Stream #0:0 (libx264)
    
Press [q] to stop, [?] for help
    
frame=  504 fps= 39 q=-1.0 Lsize=   32182kB time=00:00:10.04 bitrate=26258.5kbits/s
    
video:32061kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.377054%
    
[libx264 @ 000002784dbeb980] frame I:30    Avg QP:19.69  size:149974
    
[libx264 @ 000002784dbeb980] frame P:299   Avg QP:23.28  size: 69423
    
[libx264 @ 000002784dbeb980] frame B:175   Avg QP:24.48  size: 43280
    
[libx264 @ 000002784dbeb980] consecutive B-frames: 30.6% 69.4%  0.0%  0.0%
    
[libx264 @ 000002784dbeb980] mb I  I16..4: 18.3% 51.4% 30.4%
    
[libx264 @ 000002784dbeb980] mb P  I16..4:  0.6%  5.6%  2.4%  P16..4: 35.9% 22.9% 15.6%  0.0%  0.0%    skip:17.0%
    
[libx264 @ 000002784dbeb980] mb B  I16..4:  0.2%  0.5%  0.3%  B16..8: 49.5% 12.4%  5.6%  direct:15.5%  skip:16.1%  L0:47.8% L1:42.1% BI:10.1%
    
[libx264 @ 000002784dbeb980] 8x8 transform intra:57.5% inter:38.5%
    
[libx264 @ 000002784dbeb980] coded y,uvDC,uvAC intra: 90.7% 0.0% 0.0% inter: 50.3% 0.0% 0.0%
    
[libx264 @ 000002784dbeb980] i16 v,h,dc,p: 32% 23% 35% 10%
    
[libx264 @ 000002784dbeb980] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11% 11% 41%  7%  5%  6%  5%  6%  8%
    
[libx264 @ 000002784dbeb980] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 18% 14% 23%  8%  7%  7%  7%  7%  8%
    
[libx264 @ 000002784dbeb980] i8c dc,h,v,p: 100%  0%  0%  0%
    
[libx264 @ 000002784dbeb980] Weighted P-Frames: Y:33.8% UV:0.0%
    
[libx264 @ 000002784dbeb980] ref P L0: 58.1% 16.3% 14.2%  9.4%  2.0%
    
[libx264 @ 000002784dbeb980] ref B L0: 79.3% 20.7%
    
[libx264 @ 000002784dbeb980] kb/s:26056.02

    The second command made everything work while the second one in the first part didn’t (the one with the -ss option), so I could be quite happy about it but I’m not that sure if FFMPEG duplicates the first frame for every video or if it’s just related to the one I’m using now, so it could be better to start off with a compressed video that has the same frame count of the original one.

    So let’s get to one final question : why does FFMPEG add a duplicated first frame at the beginning of the compressed video and how can I avoid that ?

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