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Médias (91)
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Richard Stallman et le logiciel libre
19 octobre 2011, par
Mis à jour : Mai 2013
Langue : français
Type : Texte
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Stereo master soundtrack
17 octobre 2011, par
Mis à jour : Octobre 2011
Langue : English
Type : Audio
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Elephants Dream - Cover of the soundtrack
17 octobre 2011, par
Mis à jour : Octobre 2011
Langue : English
Type : Image
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#7 Ambience
16 octobre 2011, par
Mis à jour : Juin 2015
Langue : English
Type : Audio
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#6 Teaser Music
16 octobre 2011, par
Mis à jour : Février 2013
Langue : English
Type : Audio
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#5 End Title
16 octobre 2011, par
Mis à jour : Février 2013
Langue : English
Type : Audio
Autres articles (72)
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Le profil des utilisateurs
12 avril 2011, parChaque utilisateur dispose d’une page de profil lui permettant de modifier ses informations personnelle. Dans le menu de haut de page par défaut, un élément de menu est automatiquement créé à l’initialisation de MediaSPIP, visible uniquement si le visiteur est identifié sur le site.
L’utilisateur a accès à la modification de profil depuis sa page auteur, un lien dans la navigation "Modifier votre profil" est (...) -
Configurer la prise en compte des langues
15 novembre 2010, parAccéder à la configuration et ajouter des langues prises en compte
Afin de configurer la prise en compte de nouvelles langues, il est nécessaire de se rendre dans la partie "Administrer" du site.
De là, dans le menu de navigation, vous pouvez accéder à une partie "Gestion des langues" permettant d’activer la prise en compte de nouvelles langues.
Chaque nouvelle langue ajoutée reste désactivable tant qu’aucun objet n’est créé dans cette langue. Dans ce cas, elle devient grisée dans la configuration et (...) -
Sélection de projets utilisant MediaSPIP
29 avril 2011, parLes exemples cités ci-dessous sont des éléments représentatifs d’usages spécifiques de MediaSPIP pour certains projets.
Vous pensez avoir un site "remarquable" réalisé avec MediaSPIP ? Faites le nous savoir ici.
Ferme MediaSPIP @ Infini
L’Association Infini développe des activités d’accueil, de point d’accès internet, de formation, de conduite de projets innovants dans le domaine des Technologies de l’Information et de la Communication, et l’hébergement de sites. Elle joue en la matière un rôle unique (...)
Sur d’autres sites (9886)
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How to route FFMPEG screen capture output to Python for OpenCV processing ?
16 décembre 2016, par BitaniI am trying to capture the screen of a Mac, specifically game windows, and process them in real-time using OpenCV. I currently have it working with pyscreenshot and a conversion to a numpy array, but the max framerate of this method, on any system, appears to be around 10 FPS.
Obviously with games it would be very beneficial to be able to process 30+ FPS, and so I found that FFMPEG could record the screen using this command :
ffmpeg -y -f avfoundation -capture_cursor 1 -i "1" -pix_fmt yuv420p -vf scale=1024:-1 -r 30 out.mp4
That will write the screen to a file, out.mp4, with a width of 1024 and a frame rate of 30 FPS. Works perfectly ! But now I’ve searched and searched and searched for a method to route FFMPEG’s output to Python and.. no luck.
If anybody knows of a way to do this I would be greatly appreciative, as I’ve been trying to solve this for quite a while !
Thanks, and happy holidays !
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FFMPEG and DirectX Capture in C++
13 décembre 2016, par tankyxI have a system that allows me to capture a window and save it as a mp4, using ffmpeg. I use gdigrab to capture the frame, but it is fairly slow (60ms per av_read_frame calls)
I know I can capture a game using the DirectX API, but I don’t know how to convert the resulting BMP to an AVFrame.
The following code is the DirectX code I use to capture the frame
extern void* pBits;
extern IDirect3DDevice9* g_pd3dDevice;
IDirect3DSurface9* pSurface;
g_pd3dDevice->CreateOffscreenPlainSurface(ScreenWidth, ScreenHeight,
D3DFMT_A8R8G8B8, D3DPOOL_SCRATCH,
&pSurface, NULL);
g_pd3dDevice->GetFrontBufferData(0, pSurface);
D3DLOCKED_RECT lockedRect;
pSurface->LockRect(&lockedRect,NULL,
D3DLOCK_NO_DIRTY_UPDATE|
D3DLOCK_NOSYSLOCK|D3DLOCK_READONLY)));
for( int i=0 ; i < ScreenHeight ; i++)
{
memcpy( (BYTE*) pBits + i * ScreenWidth * BITSPERPIXEL / 8 ,
(BYTE*) lockedRect.pBits + i* lockedRect.Pitch ,
ScreenWidth * BITSPERPIXEL / 8);
}
g_pSurface->UnlockRect();
pSurface->Release();And here is my read loop :
{
while (1) {
if (av_read_frame(pFormatCtx, &packet) < 0 || exit)
break;
if (packet.stream_index == videoindex) {
// Decode video frame
av_packet_rescale_ts(&packet, { 1, std::stoi(pParser->GetVal("video-fps")) }, pCodecCtx->time_base);
avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
if (frameFinished) {
pFrame->pts = i;
i++;
sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
pFrameRGB->pts = pFrame->pts;
enc.encodeFrame(pFrameRGB);
}
// Free the packet that was allocated by av_read_frame
av_free_packet(&packet);
}How can I create an AVFrame using the bmp I have, without using the av_read_frame ?
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Emscripten and Web Audio API
29 avril 2015, par Multimedia Mike — HTML5Ha ! They said it couldn’t be done ! Well, to be fair, I said it couldn’t be done. Or maybe that I just didn’t have any plans to do it. But I did it– I used Emscripten to cross-compile a CPU-intensive C/C++ codebase (Game Music Emu) to JavaScript. Then I leveraged the Web Audio API to output audio and visualize the audio using an HTML5 canvas.
Want to see it in action ? Here’s a demonstration. Perhaps I will be able to expand the reach of my Game Music site when I can drop the odd Native Client plugin. This JS-based player works great on Chrome, Firefox, and Safari across desktop operating systems.
But this endeavor was not without its challenges.
Programmatically Generating Audio
First, I needed to figure out the proper method for procedurally generating audio and making it available to output. Generally, there are 2 approaches for audio output :- Sit in a loop and generate audio, writing it out via a blocking audio call
- Implement a callback that the audio system can invoke in order to generate more audio when needed
Option #1 is not a good idea for an event-driven language like JavaScript. So I hunted through the rather flexible Web Audio API for a method that allowed something like approach #2. Callbacks are everywhere, after all.
I eventually found what I was looking for with the ScriptProcessorNode. It seems to be intended to apply post-processing effects to audio streams. A program registers a callback which is passed configurable chunks of audio for processing. I subverted this by simply overwriting the input buffers with the audio generated by the Emscripten-compiled library.
The ScriptProcessorNode interface is fairly well documented and works across multiple browsers. However, it is already marked as deprecated :
Note : As of the August 29 2014 Web Audio API spec publication, this feature has been marked as deprecated, and is soon to be replaced by Audio Workers.
Despite being marked as deprecated for 8 months as of this writing, there exists no appreciable amount of documentation for the successor API, these so-called Audio Workers.
Vive la web standards !
Visualize This
The next problem was visualization. The Web Audio API provides the AnalyzerNode API for accessing both time and frequency domain data from a running audio stream (and fetching the data as both unsigned bytes or floating-point numbers, depending on what the application needs). This is a pretty neat idea. I just wish I could make the API work. The simple demos I could find worked well enough. But when I wired up a prototype to fetch and visualize the time-domain wave, all I got were center-point samples (an array of values that were all 128).Even if the API did work, I’m not sure if it would have been that useful. Per my reading of the AnalyserNode API, it only returns data as a single channel. Why would I want that ? My application supports audio with 2 channels. I want 2 channels of data for visualization.
How To Synchronize
So I rolled my own visualization solution by maintaining a circular buffer of audio when samples were being generated. Then, requestAnimationFrame() provided the rendering callbacks. The next problem was audio-visual sync. But that certainly is not unique to this situation– maintaining proper A/V sync is a perennial puzzle in real-time multimedia programming. I was able to glean enough timing information from the environment to achieve reasonable A/V sync (verify for yourself).Pause/Resume
The next problem I encountered with the Web Audio API was pause/resume facilities, or the lack thereof. For all its bells and whistles, the API’s omission of such facilities seems most unusual, as if the design philosophy was, “Once the user starts playing audio, they will never, ever have cause to pause the audio.”Then again, I must understand that mine is not a use case that the design committee considered and I’m subverting the API in ways the designers didn’t intend. Typical use cases for this API seem to include such workloads as :
- Downloading, decoding, and playing back a compressed audio stream via the network, applying effects, and visualizing the result
- Accessing microphone input, applying effects, visualizing, encoding and sending the data across the network
- Firing sound effects in a gaming application
- MIDI playback via JavaScript (this honestly amazes me)
What they did not seem to have in mind was what I am trying to do– synthesize audio in real time.
I implemented pause/resume in a sub-par manner : pausing has the effect of generating 0 values when the ScriptProcessorNode callback is invoked, while also canceling any animation callbacks. Thus, audio output is technically still occurring, it’s just that the audio is pure silence. It’s not a great solution because CPU is still being used.
Future Work
I have a lot more player libraries to port to this new system. But I think I have a good framework set up.