Tip: If your computer is able to handle -preset superfast in realtime, you should use that instead of -preset ultrafast.
$ ffmpeg -i input -c:v libx264 -preset veryslow -qp 0 -c:a copy outputīoth examples will provide the same quality output. On the opposite end of the preset spectrum is veryslow and will encode slower than ultrafast but provide a smaller output file size: $ ffmpeg -i input -c:v libx264 -preset ultrafast -qp 0 -c:a copy output The ultrafast preset will provide the fastest encoding and is useful for quick capturing (such as screencasting): $ cat f0.VOB f1.VOB f2.VOB | ffmpeg -i - out.mp2 $ ffmpeg -f v4l2 -video_size 640x480 -i /dev/video0 -f alsa -i default -c:v libx264 -preset ultrafast -c:a aac webcam.mp4Ĭoncatenate the desired VOB files into a single stream and mux them to MPEG-2: To record a video webcam.mp4 from the webcam with audio: Where -video_size specifies the largest allowed image size from the webcam. $ ffmpeg -f v4l2 -video_size 640x480 -i /dev/video0 -c:v libx264 -preset ultrafast webcam.mp4 The following command will record a video webcam.mp4 from the webcam without audio, assuming that the webcam is correctly recognized under /dev/video0: If the video stream should not be saved as a file, but used as a virtual webcam for screen sharing purposes, see v4l2loopback#Casting X11 using FFmpeg.įFmpeg includes the video4linux2 and ALSA input devices that enable capturing webcam and audio input. Other codecs can be used if writing each frame is too slow (either due to inadequate disk performance or slow encoding), then frames will be dropped and video output will be choppy. Here, the x264 codec with the fastest possible encoding speed is used. $ ffmpeg -f x11grab -video_size 1920x1080 -framerate 25 -i $DISPLAY -f alsa -i default -c:v libx264 -preset ultrafast -c:a aac screen.mp4
To take a screencast screen.mp4 with lossy encoding and with audio: Here, the Huffyuv codec is used, which is fast, but produces huge file sizes. $ ffmpeg -f x11grab -video_size 1920x1080 -framerate 25 -i $DISPLAY -c:v ffvhuff screen.mkv To take a screencast screen.mkv with lossless encoding and without audio:
Where -video_size specifies the size of the area to capture. $ ffmpeg -f x11grab -video_size 1920x1080 -i $DISPLAY -vframes 1 screen.png See FFmpeg encoding wiki and ffmpeg(1) § EXAMPLES.įFmpeg includes the x11grab and ALSA virtual devices that enable capturing the entire user display and audio input. However you may want to force the number of threads available by the parameter -threads number.
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