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• ffmpeg v4l2 taking 100% cpu usage

  16 novembre 2022, par didentifier

  I am on Fedora 37, version is irrelevant as I had same issue on Fedora 36.

  


  I am using the following command to send video from my usb video card to v4l2loopback and the CPU usage goes to 100% and I can't do much more on my computer (i5-8600k, nvidia 2060 rtx, 16GB ram).

  


  ffmpeg -nostdin -threads 1 -f video4linux2 -video_size 1920x1080 -input_format mjpeg -i /dev/video1 -f v4l2 -preset fast -c:v copy /dev/video0

  


  previously the command was like that and the rest of the arguments was added to see if it makes any difference, it seems it doesn't change much

  


  ffmpeg -f video4linux2 -video_size 1920x1080 -input_format mjpeg -i /dev/video1 -f v4l2 -c copy /dev/video0

  


  To be honest I don't know much about ffmpeg or video in general, I was using the same command a few months ago on the same hardware with almost 0 impact to my performance, I could play games and watch videos at the same time while now I get 15 FPS in my games while I am using ffmpeg. Did anything change in ffmpeg ? Any improvements to my ffmpeg command ? Shouldn't ffmpeg not encode anything if I am using pixelformat and frame rate supported by my usb video card and if that is true shouldn't be super light ?

  


• How to encode HEVC HDR10 to SVT-AV1 HDR10 ?

  28 octobre 2022, par Mario Gratzi

  I'm currently trying to find a way to re-encode a HEVC HDR10 clip to SVT-AV1 HDR10 using ffmpeg but for some reason, I don't get ffmpeg to forward the HDR metadata to the AV1 clip. So the re-encoded AV1 clip always has very cold color grading, which does not make fun to watch at all...

  


  I then checked onto FastFlix, a similar tool to Handbrake which is basically a ffmpeg frontend. If I select SVT-AV1 as encoder here, and I check onto the raw ffmpeg command FastFlix generates, it seems that this also includes the grading information :

  


  -svtav1-params "color-primaries=9:transfer-characteristics=16:matrix-coefficients=9:mastering-display=G(0.2650,0.6900)B(0.1500,0.0600)R(0.6800,0.3200)WP(0.3127,0.3290)L(4000.0000,0.0050):content-light=368,226:enable-hdr=1"


  


  The problem for me is now, how do I get these grading information with my own ffmpeg command ?

  


• How to record depth stream from realsense L515

  22 avril 2022, par Bilal

  I have a depth camera (Intel Realsense L515) and I do like to record a video of the depth.

  


  I have seen this answer which is using FFMPEG, but I didn't know how to replicate it in my case !

  


  I'm using this code :

  


  import cv2
import numpy as np
import pyrealsense2 as rs
import time

pipeline = rs.pipeline()
config = rs.config()

"""
# Depth Mode
"""
# Resolution
res = [(1024, 768), (640, 480), (320, 240)]
resolution = res[0]
print("RealSense Resolution:{}\n".format(resolution))

# # initialize video writer
fourcc = cv2.VideoWriter_fourcc('F','F','V','1')
fps = 30
video_filename = 'output.avi'
out = cv2.VideoWriter(video_filename, fourcc, fps, resolution, False)


config.enable_stream(rs.stream.depth, resolution[0], resolution[1], rs.format.z16, 30)
profile = config.resolve(pipeline)
# Start streaming
pipeline.start(config)

# Declare sensor object and set options
depth_sensor = profile.get_device().first_depth_sensor()
depth_sensor.set_option(rs.option.visual_preset, 5) # 5 is short range, 3 is low ambient light
depth_sensor.set_option(rs.option.receiver_gain, 8)
depth_sensor.set_option(rs.option.pre_processing_sharpening, 0.0)
depth_sensor.set_option(rs.option.post_processing_sharpening, 3.0)
depth_sensor.set_option(rs.option.laser_power, 100)
depth_sensor.set_option(rs.option.confidence_threshold, 2)
# Get the sensor once at the beginning. (Sensor index: 1)

# # Filters
threshold_filter = rs.threshold_filter(min_dist=1.2, max_dist=1.4)
temporal_filter = rs.temporal_filter(smooth_alpha=0.1, smooth_delta = 9.0,persistence_control=7)

try:
    # # Filters
    threshold_filter = rs.threshold_filter(min_dist=1.2, max_dist=1.4)
    temporal_filter = rs.temporal_filter(smooth_alpha=0.1, smooth_delta = 75.0,persistence_control=0)

    tic = time.time()

    while True:
        # Wait for depth frames:
        frames = pipeline.wait_for_frames()
        depth_frame = frames.get_depth_frame()
        if not depth_frame:
            continue

        #------------
        # # FILTERS |
        #------------

        depth_frame = threshold_filter.process(depth_frame)
        depth_frame = temporal_filter.process(depth_frame)

        # Convert images to numpy arrays
        depth_array = np.asanyarray(depth_frame.get_data())
        # depth_array = np.asanyarray(colorizer.colorize(depth_frame).get_data())

        out.write(depth_array)
        toc = time.time()
        if(round(toc  - tic) > 30):
            break

finally:
    out.release()
    pipeline.stop()


  


  And getting this error :

  


  


  out.write(depth_array)
cv2.error : OpenCV(4.5.4) /tmp/pip-req-build-kneyjnox/opencv/modules/videoio/src/cap_ffmpeg.cpp:186 : error : (-215:Assertion failed) image.depth() == CV_8U in function 'write'

  


  


  Can you please tell me how can I record the depth from my camera ? thanks in advance.