Anyone knows the trick?
And how to install ffmpeg ? yum install mpeg
only returns this:
======================================================================================== Matched: mpeg ========================================================================================
libiec61883.i386 : Streaming library for IEEE1394
libiec61883.x86_64 : Streaming library for IEEE1394
qffmpeg-devel.i386 : Development package for qffmpeg
qffmpeg-devel.x86_64 : Development package for qffmpeg
qffmpeg-libs.i386 : Libraries for qffmpeg
qffmpeg-libs.x86_64 : Libraries for qffmpeg
It's on the manpage:
* You can extract images from a video, or create a video from many images: For extracting images from a video: ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg This will extract one video frame per second from the video and will output them in files named foo-001.jpeg, foo-002.jpeg, etc. Images will be rescaled to fit the new WxH values. If you want to extract just a limited number of frames, you can use the above command in combination with the -vframes or -t option, or in combination with -ss to start extracting from a certain point in time.
But of course you have to install it first. I'm on Debian and don't use yum.
[update for the other question]
i=1
for avi in *.avi; do
ffmpeg -i $avi -vframes 1 -f image2 /tmp/$i.jpg; i=$((i+1))
done
Tested and works.
[update for yet another question...]
for flv in *.flv; do
ffmpeg -i $flv -vframes 1 -f image2 ${flv%%.flv}.jpg
done
I've cobbled up this command line from various answers that works great for me to get the absolutely first frame out from a video. I use this to save a thumbnail screenshot for the video.
ffmpeg -i inputfile.mkv -vf "select=eq(n\,0)" -q:v 3 output_image.jpg
Explanation:
The select filter -vf "select=eq(n\,0)"
is to select only frame #0.
-q:v
allows you to set the quality of the output jpeg between 1 and 31. Lower the number, higher the quality. 2 - 5 works good, I use 3.
Note: This will get you an image with the same size as the video. To get a thumbnail, you can use the scale filter to get a thumbnail to fit whatever width you need, like so:
ffmpeg -i inputfile.mkv -vf "select=eq(n\,0)" -vf scale=320:-2 -q:v 3 output_image.jpg
The above command will give you a thumbnail jpeg that will be scaled to match width of 320, and height will be calculated to match the aspect ratio.
An easy to grok solution that works for me is
ffmpeg -i <input> -vframes 1 <output>.jpeg
Note that I do get an error "[swscaler @ 0x111652000] deprecated pixel format used, make sure you did set range correctly" but according to a little reading (see for example https://stackoverflow.com/a/43038480/1241736) that can safely be ignored.
来源:https://stackoverflow.com/questions/4425413/how-to-extract-the-1st-frame-and-restore-as-an-image-with-ffmpeg