Keith C. Perry on 22 Dec 2015 14:35:03 -0800

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Re: [PLUG] ffmpeg slides and cheat sheet

Glad you enjoyed it JP!

I've been swamped today so I haven't have a chance to up the vid but I think I'll take a break to do that.

As a far a conversions, remember, the beauty of ffmpeg is that you generally are telling it what you want to output because ffmpeg can automagically determine the input.  So the 720p60 coding I do for PLUG videos would work for anyone if that is the output they wanted.  Obviously a recording at 30 or 24fps would not benefit from this so you actually could omit the "-r 60" parameter and ffmpeg will retain the frame rate from the source.

I don't have the screencast command line in the slides but here it is:

ffmpeg -f alsa -ac $achans -ar 44100 -i hw:$mic -f x11grab -r 15 -s $size -i :0.0+$offset -f avi -c:a pcm_s16le -c:v mjpeg -q:v 1 $1.avi

$achans  = 2 (my webcam, a Logitech C910, is stereo)
$size = 1980x1080 (the size of the screen I'm recording)
$offset = 0,0 (using the origin since the entire screen is being recorded instead of just a window)
$1 =  the output file name that gets .avi appended

This avi will contain mjpeg video and pcm audio which Cinelerra likes.  Which for me was necessary in case I needed to do any editing. You could encode directly to mp4 but YMMV for either case.  It really depends on your hardware.

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Keith C. Perry, MS E.E.
Owner, DAO Technologies LLC
(O) +1.215.525.4165 x2033
(M) +1.215.432.5167

From: "JP Vossen" <>
To: "Philadelphia Linux User's Group Discussion List" <>
Sent: Tuesday, December 22, 2015 5:08:14 PM
Subject: [PLUG] ffmpeg slides and cheat sheet

Thanks to Keith for a very interesting `ffmpeg` talk last night at PLUG

Also, per the "ffmpeg vs. avconv" discussion my notes are: Ubuntu 14.04,
ffmpeg = avconv, but as discussed that may vary and may chance.

No pressure, but I'd be interested in both the slides and a cheat sheet
of `ffmpeg` commands to use for different things.

Things I've tried to do over the years:
* Rip audio from a video file
* Capture video of a Linux desktop (your screen-cast stuff)
* Convert .flv to <something better>
* Convert m4a to mp3
* Convert FLAC into mp3
* Convert ogg into mp3

Stuff from your,
which is already in the slides anyway.

Whatever else comes to mind.  :-)

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