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La conservation du net art au musée. Les stratégies à l’œuvre
26 mai 2011
Mis à jour : Juillet 2013
Langue : français
Type : Texte
Autres articles (47)
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Participer à sa traduction
10 avril 2011Vous pouvez nous aider à améliorer les locutions utilisées dans le logiciel ou à traduire celui-ci dans n’importe qu’elle nouvelle langue permettant sa diffusion à de nouvelles communautés linguistiques.
Pour ce faire, on utilise l’interface de traduction de SPIP où l’ensemble des modules de langue de MediaSPIP sont à disposition. ll vous suffit de vous inscrire sur la liste de discussion des traducteurs pour demander plus d’informations.
Actuellement MediaSPIP n’est disponible qu’en français et (...) -
(Dés)Activation de fonctionnalités (plugins)
18 février 2011, parPour gérer l’ajout et la suppression de fonctionnalités supplémentaires (ou plugins), MediaSPIP utilise à partir de la version 0.2 SVP.
SVP permet l’activation facile de plugins depuis l’espace de configuration de MediaSPIP.
Pour y accéder, il suffit de se rendre dans l’espace de configuration puis de se rendre sur la page "Gestion des plugins".
MediaSPIP est fourni par défaut avec l’ensemble des plugins dits "compatibles", ils ont été testés et intégrés afin de fonctionner parfaitement avec chaque (...) -
Les statuts des instances de mutualisation
13 mars 2010, parPour des raisons de compatibilité générale du plugin de gestion de mutualisations avec les fonctions originales de SPIP, les statuts des instances sont les mêmes que pour tout autre objets (articles...), seuls leurs noms dans l’interface change quelque peu.
Les différents statuts possibles sont : prepa (demandé) qui correspond à une instance demandée par un utilisateur. Si le site a déjà été créé par le passé, il est passé en mode désactivé. publie (validé) qui correspond à une instance validée par un (...)
Sur d’autres sites (9237)
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ffmpeg create thumbnail image of multiple images from video
21 janvier 2018, par Michael YousefSo I want to create a thumbnail image that consists of multiple images from a single video. I’m looking to make them 4x8, and I want to spread out the images uniformly throughout the video.
Ideally the final product should show 32 image captures, all downscaled to a reasonable size so they can fit on screen at the same time. Also, I’d like to have the final product have some overhead text like the video title, and I’d like to put the timestamp in the images as well.
This is an example of what I want to do. The text at the top and the timestamp in the images. This one’s 6x4 and I want 4x8 but other than that it looks about what I want.
I think ffmpeg probably has something to do this but I can’t seem to figure it out. I can generate individual screens but not collapse them into one. It’s also slower than programs I’ve used to do this in the past, not sure how they can do it as fast as they do. If I can’t get ffmpeg to do this, I’m open to using Python to accomplish this.
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Merging audio channels by FFmpeg libraries C++
13 juin 2023, par ElijaC/C++ project. There are several audio tracks with an individual number of channels. Each is processed using a avresampler. The avresampler converts all tracks to the same format. At the output of the avresampler, we get a set of channels from all audio tracks. Do the FFmpeg libraries have any standard means to merge all these audio channels into another set of audio channels using AVFrame::ch_layout to form a single audio track ? That is, no additional processing is required, except for copying channels buffers from several AVFrames of different audio tracks to new positions of one AVFrame according to the new layout and aligning the timestamps of different audio tracks, since different audio tracks can have audio frames of different sizes with different timestamps.


For example, 1 audio track with 2 channels and 2 audio tracks with 6 channels will be merged into 16 channels with silence in the "missing" channels. Or 4 audio tracks with 2 channels merged into 8 channels. Etc...


Is there a way to use a avresampler for this ? Or a avfilter ? Or something else ?


Any source code or any reading source that can help me is welcome.


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Ffmpeg input seeking - "Invalid NAL unit size"
30 janvier 2024, par DimitrisI'm trying to use ffmpeg to get a 10-second clip from the middle of a video. The execution time of the command is important, that's why I've decided to use combined input & output seeking (as illustrated here).
The input video file is a CMAF with fragmented MP4, duration of 10 minutes.


I'm testing on a Mac, Ffmpeg version is 6.1.1.


This is the command that I'm using :


ffmpeg -nostdin -y -ss 290 -copyts -start_at_zero -i https://devcdn.flowplayer.com/5f07362e-c358-41d0-857a-c64302a3fcc9/cmaf/17bdb16d-71d1-414c-a291-a028bd45b9ec/playlist_360.m3u8 -ss 300.0 -t 10 -vcodec libwebp -lossless 0 -quality 60 -compression_level 2 -loop 0 -an -sn output.webp



Result : no output file is created.


From what I understand it fails to seek position "290" in the video, probably due to "Invalid NAL unit size" errors.


Here's the output :


ffmpeg version N-106797-g580fb6a8c9-tessus Copyright (c) 2000-2022 the FFmpeg developersbuilt with Apple clang version 11.0.0 (clang-1100.0.33.17)configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --extra-version=tessus --enable-avisynth --enable-fontconfig --enable-gpl --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libmysofa --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvmaf --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-version3 --pkg-config-flags=--static --disable-ffplaylibavutil 57. 24.101 / 57. 24.101libavcodec 59. 27.100 / 59. 27.100libavformat 59. 23.100 / 59. 23.100libavdevice 59. 6.100 / 59. 6.100libavfilter 8. 37.100 / 8. 37.100libswscale 6. 6.100 / 6. 6.100libswresample 4. 6.100 / 4. 6.100libpostproc 56. 5.100 / 56. 5.100Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'https://devcdn.flowplayer.com/5f07362e-c358-41d0-857a-c64302a3fcc9/cmaf/17bdb16d-71d1-414c-a291-a028bd45b9ec/playlist_360.cmfv':Metadata:major_brand : isomminor_version : 1compatible_brands: isomavc1dashcmfccreation_time : 2024-01-30T07:41:03.000000ZDuration: 00:09:56.54, start: 0.083333, bitrate: 458 kb/sStream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 640x360 [SAR 1:1 DAR 16:9], 1 kb/s, 24 fps, 24 tbr, 90k tbn (default)Metadata:creation_time : 2024-01-30T07:41:03.000000Zhandler_name : ETI ISO Video Media Handlervendor_id : [0][0][0]ffmpeg version 6.1.1-tessus https://evermeet.cx/ffmpeg/ Copyright (c) 2000-2023 the FFmpeg developers
 built with Apple clang version 11.0.0 (clang-1100.0.33.17)
 configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --extra-version=tessus --enable-avisynth --enable-fontconfig --enable-gpl --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libmysofa --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvmaf --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxml2 --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-version3 --pkg-config-flags=--static --disable-ffplay
 libavutil 58. 29.100 / 58. 29.100
 libavcodec 60. 31.102 / 60. 31.102
 libavformat 60. 16.100 / 60. 16.100
 libavdevice 60. 3.100 / 60. 3.100
 libavfilter 9. 12.100 / 9. 12.100
 libswscale 7. 5.100 / 7. 5.100
 libswresample 4. 12.100 / 4. 12.100
 libpostproc 57. 3.100 / 57. 3.100
[hls @ 0x7fc7bb904280] Skip ('#EXT-X-VERSION:6')
[hls @ 0x7fc7bb904280] Opening 'https://devcdn.flowplayer.com/5f07362e-c358-41d0-857a-c64302a3fcc9/cmaf/17bdb16d-71d1-414c-a291-a028bd45b9ec/playlist_360.cmfv' for reading
 Last message repeated 2 times
Input #0, hls, from '[**]/playlist_360.m3u8':
 Duration: 00:09:56.46, start: 0.083333, bitrate: 0 kb/s
 Program 0 
 Metadata:
 variant_bitrate : 0
 Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 640x360 [SAR 1:1 DAR 16:9], 1 kb/s, 24 fps, 24 tbr, 90k tbn (default)
 Metadata:
 variant_bitrate : 0
 compatible_brands: isomavc1dashcmfc
 handler_name : ETI ISO Video Media Handler
 vendor_id : [0][0][0][0]
 encoder : Elemental H.264
 major_brand : isom
 minor_version : 1
 creation_time : 2024-01-30T07:41:03.000000Z
Stream mapping:
 Stream #0:0 -> #0:0 (h264 (native) -> webp (libwebp))
[hls @ 0x7fc7bb904280] Opening 'https://devcdn.flowplayer.com/5f07362e-c358-41d0-857a-c64302a3fcc9/cmaf/17bdb16d-71d1-414c-a291-a028bd45b9ec/playlist_360.cmfv' for reading
 Last message repeated 2 times
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (1772342253 > 1534).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 1538
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-1977545460 > 1481).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 1485
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (1694403391 > 1582).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 1586
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-1404850266 > 1661).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 1665
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (703351242 > 1680).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 1684
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-836978648 > 1751).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 1755
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (752797651 > 1867).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 1871
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-1831058223 > 1833).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 1837
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-1238958831 > 2067).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2071
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (435683248 > 2090).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2094
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (2136335178 > 2229).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2233
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-1468707300 > 2203).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2207
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (482758774 > 2402).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2406
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-1079612217 > 2417).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2421
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-608087491 > 2546).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2550
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-1457748625 > 2527).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2531
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (1933919710 > 2734).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2738
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (1004643870 > 2803).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2807
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-207765435 > 2988).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2992
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-196888537 > 2306).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2310
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (1118966683 > 2620).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2624
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (1325583054 > 2715).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2719
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-2003602869 > 2906).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2910
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (1666330272 > 3085).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 3089
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (-742329993 > 2593).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2597
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (1326266794 > 2347).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2351
[NULL @ 0x7fc7bb804f40] Invalid NAL unit size (2459776 > 2155).
[NULL @ 0x7fc7bb804f40] missing picture in access unit with size 2159
[https @ 0x7fc7ba022a00] Opening 'https://devcdn.flowplayer.com/5f07362e-c358-41d0-857a-c64302a3fcc9/cmaf/17bdb16d-71d1-414c-a291-a028bd45b9ec/playlist_360.cmfv' for reading
[...]
[vost#0:0/libwebp @ 0x7fc7bbb05780] No filtered frames for output stream, trying to initialize anyway.
Output #0, webp, to 'output.webp':
 Metadata:
 encoder : Lavf60.16.100
 Stream #0:0(und): Video: webp, yuv420p(progressive), 640x360 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 24 fps, 1k tbn (default)
 Metadata:
 variant_bitrate : 0
 compatible_brands: isomavc1dashcmfc
 handler_name : ETI ISO Video Media Handler
 vendor_id : [0][0][0][0]
 creation_time : 2024-01-30T07:41:03.000000Z
 major_brand : isom
 minor_version : 1
 encoder : Lavc60.31.102 libwebp
[out#0/webp @ 0x7fc7bbb04900] video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
[out#0/webp @ 0x7fc7bbb04900] Output file is empty, nothing was encoded(check -ss / -t / -frames parameters if used)
frame= 0 fps=0.0 q=0.0 Lsize= 0kB time=N/A bitrate=N/A speed=N/A 



What I've tried so far :


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Downloaded the input file to a local directory and used it as input to ffmpeg - same results.


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Used the mp4 file from the playlist directly as an input to ffmpeg - worked but execution time is very slow


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Emmited the input seeking part (-ss 290 -copyts -start_at_zero) from the command - worked but also very slow in terms of execution time










Any ideas on why I'm getting "Invalid NAL unit size" and how to make the command work with input seeking ?


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