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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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Piwik PRO is hiring a Technical Support Specialist (Remote)
13 mars 2015, par Piwik Core Team — JobsAt Piwik and Piwik PRO we develop the leading open source web analytics platform, used by more than one million websites worldwide. Our vision is to build the best open alternative to Google Universal Analytics. We are growing and now looking for a Technical Support Specialist !
What will you be doing ?
- Supporting Piwik PRO clients on a daily basis – providing rapid responses via phone and email.
- Participating in calls with Piwik PRO clients analyzing requirements for enterprise customers.
- Onboarding clients – planning and coordinating the implementation with the dedicated technical team.
- Communicating complex problems to the dedicated technical team.
We can promise you :
- A competitive salary.
- The opportunity to develop your skills and gain more experience by working on exceptional projects.
- Access to a regularly updated resource library and the opportunity to contribute to it.
- Flexible working hours.
Desired Skills and Experience
You won’t make it without :
- A solid technical background and a familiarity with the IT sector.
- A receptive mind.
- Great English communication skills (speaking, reading, writing, and listening).
- Previous experience of working with corporate clients and a sixth sense for striking up relationships.
- Appropriately mixed abilities : solid communication skills, inquisitiveness and an analytical mind (have the ability to draw conclusions based on gathered data).
- Great self-organization skills.
About Piwik PRO
At Piwik and Piwik PRO we develop the leading open source web analytics platform, used by over 1.1M websites worldwide and is currently ranked the 7th most used web analytics tool in the world. Our vision is to build the best open alternative to Google Universal Analytics.
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Piwik PRO provides cloud hosting solutions and enterprise-level support and consultancy services. We’re in the process of expanding our US team and are currently seeking to hire a Technical Support Specialist who will focus on assisting our US clients.
Location
Ideally you will be located in the USA or Canada (Remote work).
Apply online
To apply for this position, please Apply online here. We look forward to receiving your applications !
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Piwik PRO is hiring a Technical Support Specialist (Remote)
13 mars 2015, par Piwik Core Team — JobsAt Piwik and Piwik PRO we develop the leading open source web analytics platform, used by more than one million websites worldwide. Our vision is to build the best open alternative to Google Universal Analytics. We are growing and now looking for a Technical Support Specialist !
What will you be doing ?
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- Participating in calls with Piwik PRO clients analyzing requirements for enterprise customers.
- Onboarding clients – planning and coordinating the implementation with the dedicated technical team.
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We can promise you :
- A competitive salary.
- The opportunity to develop your skills and gain more experience by working on exceptional projects.
- Access to a regularly updated resource library and the opportunity to contribute to it.
- Flexible working hours.
Desired Skills and Experience
You won’t make it without :
- A solid technical background and a familiarity with the IT sector.
- A receptive mind.
- Great English communication skills (speaking, reading, writing, and listening).
- Previous experience of working with corporate clients and a sixth sense for striking up relationships.
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- Great self-organization skills.
About Piwik PRO
At Piwik and Piwik PRO we develop the leading open source web analytics platform, used by over 1.1M websites worldwide and is currently ranked the 7th most used web analytics tool in the world. Our vision is to build the best open alternative to Google Universal Analytics.
The Piwik platform collects, stores and processes a lot of information : hundreds of millions of data points each month. We create intuitive, simple and beautiful reports that delight our users.
Piwik PRO provides cloud hosting solutions and enterprise-level support and consultancy services. We’re in the process of expanding our US team and are currently seeking to hire a Technical Support Specialist who will focus on assisting our US clients.
Location
Ideally you will be located in the USA or Canada (Remote work).
Apply online
To apply for this position, please Apply online here. We look forward to receiving your applications !
-
Overlaying a transparent webm on an MP4 freezes at the start sometimes
23 janvier 2021, par joshlat94I'm currently using the command

ffmpeg -i mainvideo.mp4 -vcodec libvpx -i myoverlay.webm -filter_complex "overlay = 5:5" done.mp4

To overlay a transparent webm on top of my main mp4. But for some reason the output video is frozen for the first 1 second but the audio is completely fine.

I've tried this command with other videos and it works sometimes but most of the time the first few frames seem frozen


Edit.
I have two main mp4 files, broken_source.mp4 and working_source.mp4. Putting the overlay on broken_source results in the output having the first 1 second of video frozen (audio completely fine) but putting the same overlay on working_source.mp4 is perfect and has no issues


Logs for putting the overlay on working_source :


ffmpeg -i working_source.mp4 -vcodec libvpx -i chat.webm -filter_complex "overlay = 0:0" working_complete.mp4
ffmpeg version 4.3.1-2021-01-01-full_build-www.gyan.dev Copyright (c) 2000-2021 the FFmpeg developers
 built with gcc 10.2.0 (Rev5, Built by MSYS2 project)
 configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-lzma --enable-libsnappy --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libzvbi --enable-librav1e --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
 libavutil 56. 51.100 / 56. 51.100
 libavcodec 58. 91.100 / 58. 91.100
 libavformat 58. 45.100 / 58. 45.100
 libavdevice 58. 10.100 / 58. 10.100
 libavfilter 7. 85.100 / 7. 85.100
 libswscale 5. 7.100 / 5. 7.100
 libswresample 3. 7.100 / 3. 7.100
 libpostproc 55. 7.100 / 55. 7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'working_source.mp4':
 Metadata:
 major_brand : isom
 minor_version : 512
 compatible_brands: isomiso2avc1mp41
 encoder : Lavf58.51.101
 Duration: 00:00:31.02, start: 0.000000, bitrate: 6176 kb/s
 Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 6035 kb/s, 60 fps, 60 tbr, 90k tbn, 120 tbc (default)
 Metadata:
 handler_name : VideoHandler
 Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
 Metadata:
 handler_name : SoundHandler
[libvpx @ 0000016fb5074a80] v1.9.0-128-g3a38edea2
 Last message repeated 1 times
Input #1, matroska,webm, from 'chat.webm':
 Metadata:
 ENCODER : Lavf58.51.101
 Duration: 00:00:31.00, start: 0.000000, bitrate: 449 kb/s
 Stream #1:0: Video: vp8, yuva420p(tv, progressive), 500x300, SAR 1:1 DAR 5:3, 60 fps, 60 tbr, 1k tbn, 1k tbc (default)
 Metadata:
 alpha_mode : 1
 ENCODER : Lavc58.101.101 libvpx
 DURATION : 00:00:31.000000000
[libvpx @ 0000016fb50761c0] v1.9.0-128-g3a38edea2
Stream mapping:
 Stream #0:0 (h264) -> overlay:main (graph 0)
 Stream #1:0 (libvpx) -> overlay:overlay (graph 0)
 overlay (graph 0) -> Stream #0:0 (libx264)
 Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libvpx @ 0000016fb50761c0] v1.9.0-128-g3a38edea2
[libx264 @ 0000016fb5072040] using SAR=1/1
[libx264 @ 0000016fb5072040] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0000016fb5072040] profile High, level 4.2, 4:2:0, 8-bit
[libx264 @ 0000016fb5072040] 264 - core 161 r3027 4121277 - H.264/MPEG-4 AVC codec - Copyleft 2003-2020 - 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=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=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=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'working_complete.mp4':
 Metadata:
 major_brand : isom
 minor_version : 512
 compatible_brands: isomiso2avc1mp41
 encoder : Lavf58.45.100
 Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 60 fps, 15360 tbn, 60 tbc (default)
 Metadata:
 encoder : Lavc58.91.100 libx264
 Side data:
 cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
 Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
 Metadata:
 handler_name : SoundHandler
 encoder : Lavc58.91.100 aac
frame= 1861 fps= 44 q=-1.0 Lsize= 20013kB time=00:00:31.01 bitrate=5285.3kbits/s speed=0.729x
video:19477kB audio:486kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.244893%
[libx264 @ 0000016fb5072040] frame I:8 Avg QP:19.04 size:240534
[libx264 @ 0000016fb5072040] frame P:538 Avg QP:23.76 size: 23836
[libx264 @ 0000016fb5072040] frame B:1315 Avg QP:31.66 size: 3951
[libx264 @ 0000016fb5072040] consecutive B-frames: 3.0% 3.5% 14.8% 78.7%
[libx264 @ 0000016fb5072040] mb I I16..4: 6.4% 47.4% 46.2%
[libx264 @ 0000016fb5072040] mb P I16..4: 1.2% 4.2% 1.9% P16..4: 21.4% 5.3% 2.9% 0.0% 0.0% skip:63.1%
[libx264 @ 0000016fb5072040] mb B I16..4: 0.1% 0.2% 0.1% B16..8: 12.6% 1.5% 0.5% direct: 0.4% skip:84.6% L0:35.9% L1:60.0% BI: 4.1%
[libx264 @ 0000016fb5072040] 8x8 transform intra:55.5% inter:60.0%
[libx264 @ 0000016fb5072040] coded y,uvDC,uvAC intra: 63.5% 77.4% 40.4% inter: 3.7% 4.6% 0.7%
[libx264 @ 0000016fb5072040] i16 v,h,dc,p: 19% 37% 15% 29%
[libx264 @ 0000016fb5072040] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 16% 18% 23% 7% 7% 7% 7% 6% 8%
[libx264 @ 0000016fb5072040] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 20% 22% 17% 7% 8% 7% 7% 6% 6%
[libx264 @ 0000016fb5072040] i8c dc,h,v,p: 45% 27% 18% 11%
[libx264 @ 0000016fb5072040] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0000016fb5072040] ref P L0: 74.5% 13.9% 9.1% 2.5%
[libx264 @ 0000016fb5072040] ref B L0: 91.9% 7.4% 0.7%
[libx264 @ 0000016fb5072040] ref B L1: 96.6% 3.4%
[libx264 @ 0000016fb5072040] kb/s:5144.05
[aac @ 0000016fb5026a80] Qavg: 193.230 



Logs for putting the overlay on broken_source :


ffmpeg -i broken_source.mp4 -vcodec libvpx -i chat.webm -filter_complex "overlay = 0:0" broken_complete.mp4
ffmpeg version 4.3.1-2021-01-01-full_build-www.gyan.dev Copyright (c) 2000-2021 the FFmpeg developers
 built with gcc 10.2.0 (Rev5, Built by MSYS2 project)
 configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-lzma --enable-libsnappy --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libzvbi --enable-librav1e --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
 libavutil 56. 51.100 / 56. 51.100
 libavcodec 58. 91.100 / 58. 91.100
 libavformat 58. 45.100 / 58. 45.100
 libavdevice 58. 10.100 / 58. 10.100
 libavfilter 7. 85.100 / 7. 85.100
 libswscale 5. 7.100 / 5. 7.100
 libswresample 3. 7.100 / 3. 7.100
 libpostproc 55. 7.100 / 55. 7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'broken_source.mp4':
 Metadata:
 major_brand : isom
 minor_version : 512
 compatible_brands: isomiso2avc1mp41
 encoder : Lavf58.26.101
 Duration: 00:00:45.02, start: 0.000000, bitrate: 5962 kb/s
 Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 5952 kb/s, 60 fps, 60 tbr, 90k tbn, 120 tbc (default)
 Metadata:
 handler_name : VideoHandler
 Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
 Metadata:
 handler_name : SoundHandler
[libvpx @ 0000021071f90280] v1.9.0-128-g3a38edea2
 Last message repeated 1 times
Input #1, matroska,webm, from 'chat.webm':
 Metadata:
 ENCODER : Lavf58.51.101
 Duration: 00:00:31.00, start: 0.000000, bitrate: 449 kb/s
 Stream #1:0: Video: vp8, yuva420p(tv, progressive), 500x300, SAR 1:1 DAR 5:3, 60 fps, 60 tbr, 1k tbn, 1k tbc (default)
 Metadata:
 alpha_mode : 1
 ENCODER : Lavc58.101.101 libvpx
 DURATION : 00:00:31.000000000
[libvpx @ 0000021072020dc0] v1.9.0-128-g3a38edea2
 Stream #0:0 (h264) -> overlay:main (graph 0)
 Stream #1:0 (libvpx) -> overlay:overlay (graph 0)
 overlay (graph 0) -> Stream #0:0 (libx264)
 Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libvpx @ 0000021072020dc0] v1.9.0-128-g3a38edea2
[libx264 @ 0000021072022980] using SAR=1/1
[libx264 @ 0000021072022980] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0000021072022980] profile High, level 4.2, 4:2:0, 8-bit
[libx264 @ 0000021072022980] 264 - core 161 r3027 4121277 - H.264/MPEG-4 AVC codec - Copyleft 2003-2020 - 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=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=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=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'broken_complete.mp4':
 Metadata:
 major_brand : isom
 minor_version : 512
 compatible_brands: isomiso2avc1mp41
 encoder : Lavf58.45.100
 Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 60 fps, 15360 tbn, 60 tbc (default)
 Metadata:
 encoder : Lavc58.91.100 libx264
 Side data:
 cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
 Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
 Metadata:
 handler_name : SoundHandler
 encoder : Lavc58.91.100 aac
frame= 2701 fps= 47 q=-1.0 Lsize= 23020kB time=00:00:45.01 bitrate=4189.5kbits/s dup=60 drop=0 speed=0.789x
video:22242kB audio:708kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.309473%
[libx264 @ 0000021072022980] frame I:11 Avg QP:18.82 size:210832
[libx264 @ 0000021072022980] frame P:742 Avg QP:23.14 size: 18106
[libx264 @ 0000021072022980] frame B:1948 Avg QP:31.16 size: 3604
[libx264 @ 0000021072022980] consecutive B-frames: 1.7% 4.2% 6.2% 87.8%
[libx264 @ 0000021072022980] mb I I16..4: 10.0% 46.2% 43.7%
[libx264 @ 0000021072022980] mb P I16..4: 1.6% 4.5% 1.5% P16..4: 16.5% 4.2% 2.4% 0.0% 0.0% skip:69.3%
[libx264 @ 0000021072022980] mb B I16..4: 0.1% 0.3% 0.1% B16..8: 11.3% 1.4% 0.4% direct: 0.4% skip:86.0% L0:36.5% L1:59.3% BI: 4.3%
[libx264 @ 0000021072022980] 8x8 transform intra:57.4% inter:64.8%
[libx264 @ 0000021072022980] coded y,uvDC,uvAC intra: 55.4% 42.1% 14.8% inter: 3.3% 2.1% 0.3%
[libx264 @ 0000021072022980] i16 v,h,dc,p: 21% 37% 15% 27%
[libx264 @ 0000021072022980] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 18% 18% 24% 6% 7% 6% 7% 6% 7%
[libx264 @ 0000021072022980] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 21% 22% 16% 7% 7% 7% 7% 6% 6%
[libx264 @ 0000021072022980] i8c dc,h,v,p: 58% 22% 15% 5%
[libx264 @ 0000021072022980] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0000021072022980] ref P L0: 68.9% 16.6% 10.8% 3.6%
[libx264 @ 0000021072022980] ref B L0: 91.6% 7.2% 1.2%
[libx264 @ 0000021072022980] ref B L1: 95.9% 4.1%
[libx264 @ 0000021072022980] kb/s:4047.35
[aac @ 0000021072024840] Qavg: 189.405