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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.

• "How can we use Ffmpeg to apply blur, overlay a logo and waveform, and add a border around a video, step by step ? [closed]

  1er février 2024, par itsfaisalkhalid

  We're looking to enhance a video using Ffmpeg by implementing several effects sequentially. First, we aim to apply a blur effect to the entire video. Then, we want to overlay a logo and a waveform onto the blurred video. Finally, we need to add a border around the entire composition. This step-by-step process requires precise commands and careful consideration of parameters to achieve the desired result effectively.

  


  I utilized Ffmpeg commands to sequentially apply blur, overlay the logo and waveform, and add a border to the video. I expected each effect to be applied in the specified order, resulting in a visually enhanced video with all desired elements. However, I encountered challenges in properly configuring the parameters for each effect, leading to unexpected results such as misaligned overlays or improper blur intensity.

  


  @echo off
setlocal enabledelayedexpansion

rem Set paths and directories
set "ffmpeg_path=C:\ffmpeg\bin\ffmpeg.exe"
set "input_dir=_input"
set "output_dir=_output"

rem Ensure input and output directories exist
if not exist "%input_dir%" (
    echo Error: Input directory "%input_dir%" not found.
    exit /b 1
)

if not exist "%output_dir%" (
    mkdir "%output_dir%"
)

rem Loop through input directory
for %%t in ("%input_dir%\*.*") DO (

    rem Process each file with ffmpeg
"%ffmpeg_path%" -y -i "%%t" -i logo.png -filter_complex "\
    [0:v]eq=brightness=0.2:saturation=2.0:contrast=1.2, crop=iw/1.2:ih/1.2, \
    boxblur=1:2 [blurred_bg]; \
    [blurred_bg][1:v]overlay=(main_w-overlay_w)/2:(main_h-overlay_h-10)[bg_with_logo]; \
    [0:a]showwaves=s=1080x100:mode=line:colors=white [waveform]; \
    [bg_with_logo][waveform]overlay=10:H-h-10, \
    format=yuv420p[v]; \
    [v]pad=iw+20:ih+20:x=10:y=10:color=white[final_output]" \
    -map "[final_output]" -map 0:a -c:v h264 -c:a aac -b:a 128k -ar 44100 "%output_dir%\temp.mp4"

    rem Check if output file exists
    if exist "%output_dir%\temp.mp4" (
        rem Calculate new MD5 hash
        certutil -hashfile "%output_dir%\temp.mp4" MD5 > "%output_dir%\temp_md5.txt"

        rem Remove ID3 tag metadata
        "%ffmpeg_path%" -i "%output_dir%\temp.mp4" -map_metadata -1 -c:v copy -c:a copy "%output_dir%\%%~nt.mp4"

        rem Clean up temporary files
        del "%output_dir%\temp.mp4"
        del "%output_dir%\temp_md5.txt"
    ) else (
        echo Error: Failed to create output file for "%%~nt"
    )
)

pause



  


• 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.