I just want some confirmation, because I have the sneaking suspicion that I wont be able to do what I want to do, given that I already ran into some errors about ffmpeg not being able to overwrite the input file. I still have some hope that what I want to do is some kind of exception, but I doubt it.
I already used ffmpeg to extract a specific frame into its own image file, I've set the thumbnail of a video with an existing image file, but I can't seem to figure out how to set a specific frame from the video as the thumbnail. I want to do this without having to extract the frame into a separate file and I don't want to create an output file, I want to edit the video directly and change the thumbnail using a frame from the video itself. Is that possible?
You're probably better off asking it in IRC zeronode #ffmpeg-devel.
I'd look at "-ss 33.5" or a more precise filter "-vf 'select=gte(n,1000)'" both will give same or very similar result at 30 fps video.
You can pipe the image out to your own process via pipe if you like of course without saving it : "ffmpeg ... -f jpeg -|..."
Related
I am using this PyLivestream library to stream files to youtube. the problem is that once it finishes each video the scren goes down for a second until the next video starts. because it's simply just creating ffmpeg command and running then directly in a subprocess for each media file.
Is it possible to configure an instance of ffmpeg that will always be streaming to the destination. It could just be a blank screen or an image. And it also has an input, so I can point PyLivestream to the repeater.
This way the repeater will create one long un-interupted stream experience, but I can still use PyLivestream to stream the individual files.
The mvhd atom or box of the original Quicktime MOV format supports a poster time variable for a timecode to use as a poster frame that can be used in preview scenarios as a thumbnail image or cover picture. As far as I can tell, the ISOBMFF-based MP4 format (.m4v) has inherited this feature, but I cannot find a way to set it using FFmpeg or MP4box or similar cross-platform CLI software. Edit: Actually, neither ISOBMFF nor MP4 imports this feature from MOV. Is there any other way to achieve this, e.g. using something like HEIFʼs derived images with a thmb (see Amendment 2) role?
The original Apple Quicktime (Pro) editor did have a menu option for doing just that. (Apple Compressor and Photos could do it, too).
To be clear, I do not want to attach a separate image file, which could possibly be a screenshot grabbed from a movie still, as a separate track to the multimedia container. I know how to do that:
Stackoverflow #54717175
Superuser #597945
I also know that some people used to copy the designated poster frame from its original position to the very first frame, but many automatically generated previews use a later time index, e.g. from 10 seconds, 30 seconds, 10% or 50% into the video stream.
I wish to add a frame to the end of a video just after it has been captured so I can make a timelapse video as the images are acquired.
So the idea is to take an image, use ffpmeg to make the video by adding each image just after it is aqcuired.
I've seen many questions about adding a set length of time of a logo type image or how to compile a whole bunch of single images to a video but not this.
Anyone got a good idea of what to try?
I have been looking for a way to convert a sequence of PNGs to a video. There are ways to do that using the CONCAT function within FFmpeg and using a script.
The problem is that I want to show certain images longer than others. And I need it to be accurate. I can set a duration (in seconds) in the script file. But I need it to be frame-accurate. So far I have not been successful.
This is what I want to make:
Quicktime video with transparancy (Prores4444 or other codec that supports transparancy + alpha channel)
25fps
This is what I have: [ TimecodeIn - TimecodeOut in destination video ]
img001.png [0:00:05:10 - 0:00:07:24]
img002.png [0:00:09:02 - 0:00:12:11]
img003.png [0:00:15:00 - 0:00:17:20]
...
img120.png [0:17:03:11 - 0:17:07:01]
Of course this is not the format of the script file. Just an idea about what kind of data I am dealing with. The PNG-imagefiles are subtitles I generate elsewhere in my application. I would like to be able to export the subtitles as a transparent movie that I can easily import in my video editing software.
I also have been thinking of using blank transparent images I will use as spacers, between the actual subtitle images.
After looking around I think this might help:
On the FFMPEG site they explain about making a timed slideshow
In the Concat demuxer section they talk about making a slideshow, based on a text file, with references to the image files and the duration of the image.
So, I create all the PNG images I need. These images have the subtitle text. Each image holds one subtitle page.
For the moments I want to hide the subtitle, I use a blank PNG.
I generate a text file as explained on the FFMPEG website.
This text file will reference to all the PNGs. For the duration I just calculate the outcue - incue. Easy... I think...
In what language can I write a quick program to take screenshots and also possibly emulate a keypress?
I have an animated/interactive flash movie that is a presentation. I want to take a screenshot after I press a particular key.
The end effect is a bunch of screenshots that I can print...basically captures the key moments in the flash presentation.
I've written this in C# without much hassle. Here's the bulk of the code:
using (Bitmap bitmap = new Bitmap(bitmapSize.Width, bitmapSize.Height, PixelFormat.Format24bppRgb))
using (Graphics graphics = Graphics.FromImage(bitmap))
{
graphics.CopyFromScreen(
new Point(0, 0),
new Point(0, 0),
bitmapSize);
bitmap.Save(filename, ImageFormat.Png);
}
I would recommend writing an app that hosts a browser control. Then you could have the browser control show the SWF and your app would know the exact coordinates of the part of the screen you need to capture. That way you can avoid having to capture a whole screen or whole window that you may have to crop later.
i am sure there are ways, but here's my idea. you can convert your movie frames to pictures using tools like ffmpeg . From the man page of ffmpeg
ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
This will extract one video frame per second from the video and will output them in files named foo-001.jpeg, foo-002.jpeg, etc.
Images will be rescaled to fit the new WxH values.
If you want to extract just a limited number of frames, you can use the above command in combination with the -vframes or -t option,
or in combination with -ss to start extracting from a certain point in time.
The number in the file name "simulates" the key press, so if you extracted for 1 sec per frame, and you want to "press" the key at 30sec, use the file name with foo-030.jpeg
There's a free tool that I found about recently that does the screen capture part, It's apparently written in java.
http://screenr.com/