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• ffmpeg does not record video and audio simultaneously

  28 mars 2016, par dilip yadav

  For video recording I am using :
  ffmpeg -f v4l2 -i /dev/video0 -vcodec h264 -r 20 /home/test.avi

  For audio recording I am using :
  ffmpeg -f alsa -acodec pcm_alaw -ar 8k -ac 1 /home/w2.wav

  Both commands work fine.
  When I combine both of them like :
  ffmpeg -f v4l2 -i /dev/video0 -f alsa -i hw:0,0 -acodec pcm_alaw -ar 8k -ac 1 -vcodec h264 -r 23  /home/test.avi

  It throws :

  [alsa @ 0x2650500] ALSA buffer xrun.
  
  [alsa @ 0x2650500] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)

  Audio is not recorded, but video is recorded. I don’t know what I am doing wrong.Please help.

• Record video with Xvfb + FFmpeg using Selenium in headless mode

  12 mars 2024, par ifdef14

  I am trying to record video using Selenium in headless mode. I am using Xvfb and FFmpeg bindings for Python. I've already tried :

  


  import subprocess
import threading
import time

from chromedriver_py import binary_path
from selenium import webdriver
from selenium.webdriver.chrome.service import Service
from xvfbwrapper import Xvfb


def record_video(xvfb_width, xvfb_height, xvfb_screen_num):
    subprocess.call(
        [
            'ffmpeg',
            '-f',
            'x11grab',
            '-video_size',
            f'{xvfb_width}x{xvfb_height}',
            '-i',
            xvfb_screen_num,
            '-codec:v',
            'libx264',
            '-r',
            '12',
            'videos/video.mp4',
        ]
    )


with Xvfb() as xvfb:
    '''
    xvfb.xvfb_cmd[1]) returns scren num
    :217295622
    :319294854
    :
    '''
    xvfb_width, xvfb_height, xvfb_screen_num = xvfb.width, xvfb.height, xvfb.xvfb_cmd[1]
    thread = threading.Thread(target=record_video, args=(xvfb_width, xvfb_height, xvfb_screen_num))
    thread.start()
    opts = webdriver.ChromeOptions()
    opts.add_argument('--headless')
    try:
        driver = webdriver.Chrome(service=Service(executable_path=binary_path), options=opts)
    finally:
        driver.close()
        driver.quit()



  


  As much as I understand xvfb.xvfb_cmd[1] returns an information about virtual display isn't it ? When I executed this script, I got the error message :

  


  [x11grab @ 0x5e039cfe2280] Failed to query xcb pointer0.00 bitrate=N/A speed=N/A    
:1379911620: Generic error in an external library


  


  I also tried to use the following commands :

  


  xvfb-run --listen-tcp --server-num 1 --auth-file /tmp/xvfb.auth -s "-ac -screen 0 1920x1080x24" python main.py &

  


  ffmpeg -f x11grab -video_size 1920x1080 -i :1 -codec:v libx264 -r 12 videos/video.mp4

  


  In the commands above, there are used xvfb-run --server-num 1 and ffmpeg -i :1, why ?

  


  Overall, when Selenium is running in the headless mode what's going on behind the scenes ? Is it using virtual display ? If yes, how can I detect display id of this, etc. Am I on the right path ?

  


  I am not using Docker or any kind of virtualization. All kind of tests are running on my local Ubuntu machine.

  


• FFMPEG record output audio for Mac

  14 mars 2017, par hardier

  I am trying to use ffmpeg recording screen as well as incoming audio on mac, but in the input device lists, there is no "speaker". Is there a way to get output audio ?

  $ ffmpeg -f avfoundation -list_devices true -i ""
  
  
  
  configuration: --prefix=/usr/local --enable-gpl --enable-nonfree --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid
  
  libavutil      55. 18.100 / 55. 18.100
  
  libavcodec     57. 24.105 / 57. 24.105
  
  libavformat    57. 26.100 / 57. 26.100
  
  libavdevice    57.  0.101 / 57.  0.101
  
  libavfilter     6. 34.100 /  6. 34.100
  
  libswscale      4.  0.100 /  4.  0.100
  
  libswresample   2.  0.101 /  2.  0.101
  
  libpostproc    54.  0.100 / 54.  0.100
  
  [AVFoundation input device @ 0x7fd5f9600360] AVFoundation video devices:
  
  [AVFoundation input device @ 0x7fd5f9600360] [0] FaceTime HD Camera
  
  [AVFoundation input device @ 0x7fd5f9600360] [1] Capture screen 0
  
  [AVFoundation input device @ 0x7fd5f9600360] [2] Capture screen 1
  
  [AVFoundation input device @ 0x7fd5f9600360] AVFoundation audio     devices:
  
  [AVFoundation input device @ 0x7fd5f9600360] [0] Soundflower (2ch)
  
  [AVFoundation input device @ 0x7fd5f9600360] [1] Built-in Microphone
  
  [AVFoundation input device @ 0x7fd5f9600360] [2] Soundflower (64ch)
  
  : Input/output error