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Médias (1)
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Rennes Emotion Map 2010-11
19 octobre 2011, par
Mis à jour : Juillet 2013
Langue : français
Type : Texte
Autres articles (21)
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Il fournit également une page supplémentaire qui n’apparait que lorsque certains plugins sont activés permettant de contrôler l’affichage et les fonctionnalités spécifiques (...) -
Use, discuss, criticize
13 avril 2011, parTalk to people directly involved in MediaSPIP’s development, or to people around you who could use MediaSPIP to share, enhance or develop their creative projects.
The bigger the community, the more MediaSPIP’s potential will be explored and the faster the software will evolve.
A discussion list is available for all exchanges between users. -
Emballe médias : à quoi cela sert ?
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Sur d’autres sites (2866)
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Revision 30148 : On pousse encore un peu plus loin la conf (toujours pas utilisable dans ...
24 juillet 2009, par kent1@… — LogOn pousse encore un peu plus loin la conf (toujours pas utilisable dans l’état)
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avformat/hls : Be more picky on extensions
16 janvier, par Michael Niedermayeravformat/hls : Be more picky on extensions
This blocks disallowed extensions from probing
It also requires all available segments to have matching extensions to the format
mpegts is treated independent of the extensionIt is recommended to set the whitelists correctly
instead of depending on extensions, but this should help a bit,
and this is easier to backportFixes : CVE-2023-6602 II. HLS Force TTY Demuxer
Fixes : CVE-2023-6602 IV. HLS XBIN Demuxer DoS AmplificationThe other parts of CVE-2023-6602 have been fixed by prior commits
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Signed-off-by : Michael Niedermayer <michael@niedermayer.cc> -
Record video stream in rust
19 novembre 2024, par El_LocoI have bought a stereo camera with global shutter and a frame rate of at most 120 fps. https://www.amazon.com/dp/B0D8T3ZSL4?ref_=pe_386300_442618370_TE_sc_as_ri_0#


My next step is to write a program that can show and record a video with desired fps and resolution.


use opencv::{
 core, highgui,
 prelude::*,
 videoio::{self, VideoCapture},
 Result,
};

fn open_camera() -> Result<videocapture> {
 let capture = videoio::VideoCapture::new(2, videoio::CAP_ANY)?;
 return Ok(capture);
}
fn main() -> Result<()> {
 let window = "video capture";
 highgui::named_window(window, highgui::WINDOW_AUTOSIZE)?;
 let mut cam = open_camera()?;
 let opened = videoio::VideoCapture::is_opened(&cam)?;
 if !opened {
 panic!("Unable to open default camera!");
 }
 let width = 3200.0;
 let height = 1200.0;
 cam.set(videoio::CAP_PROP_FRAME_WIDTH, width)?;
 cam.set(videoio::CAP_PROP_FRAME_HEIGHT, height)?;

 // Set the frame rate (FPS)
 let fps = 60.0;
 
 let fourcc = videoio::VideoWriter::fourcc('M', 'J', 'P', 'G')?;
 let mut writer = videoio::VideoWriter::new(
 "video_output.avi",
 fourcc,
 fps,
 core::Size::new(width as i32, height as i32),
 true,
 )?;

 if !writer.is_opened()? {
 println!("Error: Could not open the video writer.");
 }

 let mut frame = core::Mat::default();
 let mut ctr = 0;
 while cam.read(&mut frame)? {
 if frame.empty() {
 break;
 }
 writer.write(&frame)?;
 highgui::imshow(window, &frame)?;
 
 let key = highgui::wait_key(1)?;
 if key > 0 {
 break;
 }
 ctr += 1;
 if ctr == 600 {
 break;
 }
 }
 cam.release()?;
 writer.release()?;
 Ok(())
}
</videocapture>

When I run this code the frame rate is terrible. Like 1 fps or something. For debugging I tried to run in cheese. There I got 30 fps with full resolution
3200x1200. But I cannot change the fps to 60 fps what I can see.

Then I tried to capture a video using ffmpeg :


ffmpeg -f v4l2 -framerate 60 -video_size 3200x1200 -i /dev/video2 output.mp4

With the following output :


[video4linux2,v4l2 @ 0x5a72cbbd1400] The driver changed the time per frame from 1/60 to 1/2
Input #0, video4linux2,v4l2, from '/dev/video2':
 Duration: N/A, start: 2744.250608, bitrate: 122880 kb/s
 Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 3200x1200, 122880 kb/s, 2 fps, 2 tbr, 1000k tbn
File 'output.mp4' already exists. Overwrite? [y/N]


The frame rate is lowered to 2 fps.


Then I tried to run
v4l2-ctl --list-formats-ext -d 2with the following output :

ioctl: VIDIOC_ENUM_FMT
 Type: Video Capture

 [0]: 'MJPG' (Motion-JPEG, compressed)
 Size: Discrete 3200x1200
 Interval: Discrete 0.017s (60.000 fps)
 Interval: Discrete 0.033s (30.000 fps)
 Interval: Discrete 0.040s (25.000 fps)
 Interval: Discrete 0.050s (20.000 fps)
 Interval: Discrete 0.067s (15.000 fps)
 Interval: Discrete 0.100s (10.000 fps)
 Size: Discrete 2560x720
 Interval: Discrete 0.017s (60.000 fps)
 Interval: Discrete 0.033s (30.000 fps)
 Interval: Discrete 0.040s (25.000 fps)
 Interval: Discrete 0.050s (20.000 fps)
 Interval: Discrete 0.067s (15.000 fps)
 Interval: Discrete 0.100s (10.000 fps)
 Size: Discrete 1600x600
 Interval: Discrete 0.008s (120.000 fps)
 Interval: Discrete 0.017s (60.000 fps)
 Interval: Discrete 0.033s (30.000 fps)
 Interval: Discrete 0.040s (25.000 fps)
 Interval: Discrete 0.050s (20.000 fps)
 Interval: Discrete 0.067s (15.000 fps)


I then tried to open the camera using
qv4land there it seemed to work. Does not seem like I can record a video though.

I am using Rust to learn. I want to be able to programmatically be able to record a video somehow and then do computer vision. The easiest would be to do it in Rust. But other solutions are ok.


Edit
I have found some more this morning :


v4l2-ctl -d 2 --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
 Type: Video Capture

 [0]: 'MJPG' (Motion-JPEG, compressed)
 Size: Discrete 3200x1200
 Interval: Discrete 0.017s (60.000 fps)
 Interval: Discrete 0.033s (30.000 fps)
 Interval: Discrete 0.040s (25.000 fps)
 Interval: Discrete 0.050s (20.000 fps)
 Interval: Discrete 0.067s (15.000 fps)
 Interval: Discrete 0.100s (10.000 fps)

 [1]: 'YUYV' (YUYV 4:2:2)
 Size: Discrete 3200x1200
 Interval: Discrete 0.500s (2.000 fps)
 Size: Discrete 2560x720
 Interval: Discrete 0.500s (2.000 fps)
 Size: Discrete 1600x600
 Interval: Discrete 0.100s (10.000 fps)


I also found here that order of flags was important for
ffmpeg. Running this I can actually record a video with 60 fps :

ffmpeg -framerate 60 -f v4l2 -video_size 3200x1200 -input_format mjpeg -i /dev/video2 output.avi

A drawback is that the images does not look very sharp. You can clearly see the pixels. (I am new to video formats etc as well. Before it has just worked.)


If I change from
avitomkvit is slow again.

In the link above I also saw a suggestion to first do :


ffmpeg -framerate 60 -f v4l2 -video_size 3200x1200 -input_format mjpeg -i /dev/video2 -c copy mjpeg.mkv

and then :


ffmpeg -i mjpeg.mkv -c:v libx264 -crf 23 -preset medium -pix_fmt yuv420p out.mkv

which worked. But I am not sure those flags are ideal for the camera I have. I think it is a good start to make it run as expected using command line and ffmpeg. So I know what format to use and that it actually works as intended before doing it programmatically.


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