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FFmpeg Screen Recording - Command Breakdown

·498 words·3 mins·
Linux Media Recording Ffmpeg Screen-Recording Linux Pulseaudio Recording
Table of Contents

Let me break down each part of this FFmpeg command:

Command Breakdown:
#

ffmpeg

1. Video Input (Screen Capture)
#

-f x11grab                  # Input format: X11 screen grabbing
-s 1366x768                 # Screen resolution: 1366 pixels wide × 768 pixels tall
-i :0.0                     # Input source: Display 0, Screen 0 (main screen)

2. Audio Input (Microphone)
#

-f pulse                    # Input format: PulseAudio (Linux sound server)
-i "alsa_input.usb-Jieli_Technology_UACDemoV1.0_F584CD1399EC5853-00.mono-fallback"
                            # PulseAudio device name for your USB microphone
                            # "mono-fallback" means it's a mono (single channel) device

3. Video Encoding Settings
#

-c:v libx264                # Video codec: H.264 (x264 encoder)
-preset veryfast            # Encoding speed/quality tradeoff:
                            #   ultrafast → superfast → veryfast → faster → fast
                            #   → medium → slow → slower → veryslow
                            # "veryfast" = faster encoding, larger file size
-crf 23                     # Constant Rate Factor (quality):
                            #   0 = lossless (huge files)
                            #   18-28 = typical range
                            #   23 = good quality (default)
                            #   Lower = better quality, larger files

4. Audio Encoding Settings
#

-c:a aac                    # Audio codec: AAC (Advanced Audio Coding)
-ac 1                       # Audio channels: 1 (mono) - matches your microphone
-ar 44100                   # Audio sample rate: 44.1kHz (CD quality)
# Note: No bitrate specified, so FFmpeg uses AAC default (~128kbps for stereo)

5. Output
#

out.mkv                     # Output filename with .mkv container (Matroska)
                            # MKV supports multiple audio tracks, subtitles, etc.

What This Command Does:
#

  1. Captures your entire screen (1366×768 resolution)
  2. Records audio from your USB microphone
  3. Encodes video as H.264 with “veryfast” preset (good balance)
  4. Encodes audio as AAC mono at 44.1kHz
  5. Saves everything to out.mkv file

Equivalent/Alternative Options:
#

Add framerate (optional but recommended):

-framerate 30              # Adds: Capture at 30 frames per second

Specify audio bitrate explicitly:

-b:a 128k                  # Sets audio bitrate to 128 kbps

Use shorter names:

-vcodec libx264            # Same as -c:v libx264
-acodec aac                # Same as -c:a aac

Add timestamp (for debugging):

-show_pts 1               # Shows timestamps in console (debugging)

Common Issues & Fixes:
#

If audio/video get out of sync:

-async 1                  # Audio sync method

If you want to limit file size:

-b:v 2000k                # Video bitrate: 2000 kbps
-maxrate 2500k            # Maximum bitrate
-bufsize 5000k            # Buffer size

To show progress during encoding:

-progress pipe:1          # Shows encoding progress

Example with All Common Options:
#

ffmpeg \
  -f x11grab -s 1366x768 -framerate 30 -i :0.0 \
  -f pulse -i "alsa_input.usb-Jieli_Technology_UACDemoV1.0_F584CD1399EC5853-00.mono-fallback" \
  -c:v libx264 -preset veryfast -crf 23 \
  -c:a aac -ac 1 -ar 44100 -b:a 128k \
  -async 1 \
  -y \
  out.mkv

Where -y = overwrite output without asking

To Play Back the Recording:
#

ffplay out.mkv
# or
mpv out.mkv
# or
vlc out.mkv

This command gives you a good balance of quality, file size, and encoding speed for screen recording with microphone audio.

To record only the audoi

ffmpeg -f pulse -i "alsa_input.usb-Jieli_Technology_UACDemoV1.0_F584CD1399EC5853-00.mono-fallback"        -c:a aac -ac 1 -ar 44100 -b:a 128k        -y output.m4a

ffmpeg -f pulse -i "alsa_input.usb-Jieli_Technology_UACDemoV1.0_F584CD1399EC5853-00.mono-fallback"        -c:a aac -b:a 256k -ac 2 -ar 48000        output.m4a
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Youcef
My name is youcef and i’m linux user who fool in love with linux , like free and open software .