How can I extract a good quality JPEG image from a video file with ffmpeg?
Currently I am using this command to extract the images:
ffmpeg -i input.mp4 output_%03d.jpeg
But how can I improve the JPEG image quality?
Use -qscale:v
to control quality
Use -qscale:v
(or the alias -q:v
) as an output option.
- Normal range for JPEG is 2-31 with 31 being the worst quality.
- The scale is linear with double the qscale being roughly half the bitrate.
- Recommend trying values of 2-5.
- You can use a value of 1 but you must add the
-qmin 1
output option (because the default is-qmin 2
).
To output a series of images:
ffmpeg -i input.mp4 -qscale:v 2 output_%03d.jpg
See the image muxer documentation for more options involving image outputs.
To output a single image at ~60 seconds duration:
ffmpeg -ss 60 -i input.mp4 -qscale:v 4 -frames:v 1 output.jpg
To continuously overwrite/update/save to a single image
Use -update 1
image muxer option. Example for once per second from a live streaming input:
ffmpeg -i rtmp://input.foo -q:v 4 -r 1 -update 1 output.jpg
Also see
- FFmpeg FAQ: How do I encode movie to single pictures?
- FFmpeg Wiki: Create a thumbnail image every X seconds of the video
Output the images in a lossless format such as PNG:
mkdir stills
ffmpeg -i my-film.mp4 -vsync 0 -f image2 stills/my-film-%06d.png
Then use another program (where you can more precisely specify quality, subsampling and DCT method – e.g. GIMP) to convert the PNGs you want to JPEG.
It is possible to obtain slightly sharper images in JPEG format this way than is possible with -qmin 1 -q:v 1
and outputting as JPEG directly from ffmpeg
.
If you want to extract only the key frames (which are likely to be of higher quality post-edit) you can use something like this:
ffmpeg -skip_frame nokey -i my-film.mp4 -vsync 0 -f image2 stills/my-film-%06d.png
The -vsync 0
parameter avoids needing to specify the frame rate with -r
and means all frames in the input file are treated as, um, a frame.