I'm trying to split a video by detecting the presence of a marker (an image) in the frames. I've gone over the documentation and I see removelogo but not detectlogo.
Does anyone know how this could be achieved? I know what the logo is and the region it will be on.
I'm thinking I can extract all frames to png's and then analyse them one by one (or n by n) but it might be a lengthy process...
Any pointers?
ffmpeg doesn't have any such ability natively. The delogo filter simply works by taking a rectangular region in its parameters and interpolating that region based on its surroundings. It doesn't care what the region contained previously; it'll fill in the region regardless of what it previously contained.
If you need to detect the presence of a logo, that's a totally different task. You'll need to create it yourself; if you're serious about this, I'd recommend that you start familiarizing yourself with the ffmpeg filter API and get ready to get your hands dirty. If the logo has a distinctive color, that might be a good way to detect it.
Since what you're after is probably going to just be outputting information on which frames contain (or don't contain) the logo, one filter to look at as a model will be the blackframe filter (which searches for all-black frames).
You can write a detect-logo module, Decode the video(YUV 420P FORMAT), feed the raw frame to this module, Do a SAD(Sum of Absolute Difference) on the region where you expect a logo,if SAD is negligible its a match, record the frame number. You can split the videos at these frames.
SAD is done only on Y(luma) frames. To save processing you can scale the video to a lower resolution before decoding it.
I have successfully detect logo using a rpi and coral ai accelerator in conjunction with ffmeg to to extract the jpegs. Crop the image to just the logo then apply to your trained model. Even then you will need to sample a minute or so of video to determine the actual logos identity.
Related
I'm new to stack overflow, but I've been researching how to do this for a couple weeks to no avail. I'm hoping perhaps one of you has some knowledge I haven't seen online yet.
Here is a crude illustration of what I hope to accomplish. I have a video wall of eight monitors - four each of two different sizes. The way it's set up now, all eight monitors are treated together as one big monitor displaying an oddly shaped cutout of a desktop.
Eventually I need each individual monitor to display a separate RTSP stream for about thirty seconds, then have the entire display - all eight monitors in conjunction - to fade out into a large logo.
My problem right now is that I don't know of a way to mask an rtsp stream so it looks like this rather than this, let alone how to arrange them into a weirdly spaced, oddly angled, multiple aspect-ratio mosaic like in the original illustration.
Thank you all for your time. I'm just an intern here without insane technical knowhow, but I'll try to clarify as much as I can.
-J
I believe -filter-complex is one of the ffmpeg CLI flags that you need. You can find many examples online, but here are a few links of interest:
Here's an ffmpeg wiki on creating a mosaic https://trac.ffmpeg.org/wiki/Create%20a%20mosaic%20out%20of%20several%20input%20videos
FFMpeg - Combine multiple filter_complex and overlay functions
That should get you started, but you will probably need to add customization depending on frame size and formats.
I'm trying to want to know the P-frame at mpeg.
I have a query about reference image.
Why not we use original image instead decoded image to make P-frame?
I-frame, B-frame and P-frame allows to compress the video.
Indeed, in a video you have a lot of redundant information.
Think about a car moving across the screen: all the pixels in the background do not change from a picture to another, only those around the car are "moving". With the I-B-P frame truck, you give the code of the background and then, you just signalling slight changes (the car moving) through vectors.
This way you have to carry less information than if you have to repeat the entire picture each time.
See also:
Video compression
https://stackoverflow.com/a/24084121/3194340
Assuming a simple product demo e.g. the one found on http://www.sublimetext.com/
i.e. something this isn't traditional high res video and could be reasonable accomplished with:
animated gif
video (can be embedded youtube, custom html5 player, whatever is most competitive)
canvas
The question is, which performs better for the user? Both in terms of:
The size of the files the user must be downloaded to view the 'product demo'
The requirements in terms of processing power to display the 'product demo'
If you feel that there's a superior technology to accomplish this or another metric to judge its usefulness, let me know and I'll adjust accordingly.
I know it's already answered, but as you specifically referred to the Sublime Text animation I assume you're wanting to create something similar?
If that's the case then here is a post explaining how it was created by the Sublime Text author, himself:
http://www.sublimetext.com/~jps/animated_gifs_the_hard_way.html
The interesting part of the article is how he reduces the file size - which I believe is your question.
With a simple animation such as the one at the link you're referring to, with a very low frame rate, a simple animated-PNG of animated GIF will probably be the best solution.
However, you need to consider band-width factor in this. If the final size of the GIF or the PNG is large then probably a buffered video is probably better.
This is because the whole gif/png file needs to be downloaded before it shows (I am not sure how interleaved PNGs works when they contain animation though).
A video may be larger in file size, but as it is typically buffered you will be able to show the animation almost right away.
Using external hosts such as YouTube or others can be beneficial to your site as well as the band-width is drawn from those site and not from your server (in case you use a provider that limits or charge for this in various ways).
For more information on animated PNGs or APNG (as this is not so well-known):
https://en.wikipedia.org/wiki/APNG
The canvas in this is only a displaying device and not really necessary (an image container does the same job and can also animate the GIF/PNG whereas a canvas cannot).
If you use a lot of vectors then canvas can be considered.
CSS3 animation is also an option for things such as presentation slides.
Using ffmpeg I can take a number of still images and turn them into a video. I would like to do this to decrease the total size of all my timelapse photos. But I would also like to extract the still images for use at a later date.
In order to use this method:
- I will need to correlate the original still image against a frame number in the video.
- And I will need to extract a thumbnail of a given frame number in a
video.
But before I go down this rabbit hole, I want to know if the requirements are possible using ffmpeg, and if so any hints on how to accomplish the task.
note: The still images are timelapse from a single camera over a day, so temporal compression will be measurable compared to a stack of jpegs.
When you use ffmpeg to create a video from a sequence of images, the images aren't affected in any way. You should still be able to use them for what you're trying to do, unless I'm misunderstanding your question.
Edit: You can use ffmpeg to create images from an existing video. I'm not sure how well it will work for your purposes, but the images are pretty high quality, if not the same as the originals. You'd have to play around with it to make sure the extracted images are exactly the same as the input images as far as sequential order and naming, but if you take fps into account, it should work.
The command to do this (from the ffmpeg documentation) is as follows:
ffmpeg -i movie.mpg movie%d.jpg
Is there a tool that would reveal whether an image contains a watermark and read, alter or remove a watermark if used by someone who is not the creator of the watermark?
Edit to try to reflect Kerzin's intent, as indicated in the comments: This is not for the purpose of knowing how to do it, but whether it can be done by others to remove watermarks from created images, and how it can be made more difficult.
In general:
to detect a watermark that is not visible to the naked eye you need to have some idea of the encoding scheme
it is possible to come up with a watermarking scheme that yields a watermark one cannot read or definitively confirm the presence of without knowing a secret, however in general that is not the purpose of a watermark
a watermark that does not distort the image sufficiently to be obvious to the naked eye should in general be removable by manipulations that similarly do not degrade the signal sufficiently to be obvious to the naked eye; however, coming up with the required manipulations may be hard and will certainly require specific knowledge of the watermarking scheme.
It depends on the type of watermark you're creating. I'm assuming you're talking about an opaque or semitransparent logo or text that is usually placed in a corner of the image.
There is a balancing act here. If the watermark is small enough, users can always just crop it out. But if you make it too large, you make the image unusable. Sometimes this is the intent (for example, look at iStockPhoto.com: they use big watermarks over the center of the image so that you can't use the image without buying it). Other times, you don't want to do this (say you're posting a wallpaper to DeviantArt: you still want people to use the image, but no one's going to use it if the watermark takes up a third of the screen).
If the watermark covers a part of the image that is not too detailed, users who know what they're doing can use the clone brush or other tools to photoshop it out of the image. (The same way I once removed ugly power lines from an otherwise beautiful sunset photo.)
Also, if the watermark is in the same place on all images, and it is transparent enough, sophisticated users can build a filter based on the common pixels from several of your images. In the right circumstances, such a filter can work like magic. (But usually it won't.)
Most of the time you won't be able to remove the watermark. Not even manually.
Unless it is a real simple and/or badplaced watermark and the image itself is easy to reconstruct too.
There are a few tools that claim to be able to remove watermarks but I don't know of any which really are up to the task