Awesome
GPU based optical flow extraction from videos
Forked from https://github.com/feichtenhofer/gpu_flow by Antonino Furnari
News
2020-01-09
The semantics of the dilation parameter have changed to allow finer grained configuration. Previously optical flow was
computed between frames I_{st} and I_{s(t+d)} where s is the stride and d the dilation. The code now computes flow
between I_{st} and I_{st+d}--this makes the stride and dilation parameters completely independent which is more intuitive.
If you wish to continue using the old code then use the docker image tagged with v1
. All subsequent images and the
latest
tag will adopt the new behaviour described above.
Usage
We support running via docker and singularity.
Docker
- Ensure you're running
nvidia-docker
as this software is GPU accelerated. If using docker 19.03 or above then you can use the native docker nvidia GPU support. - Pull the docker image:
$ docker pull willprice/furnari-flow
- Dump out frames from the video you wish to compute flow for:
$ mkdir my_video; ffmpeg -i my_video.mp4 -qscale 3 my_video/img_%06d.jpg
- Compute the flow using
furnari-flow
:$ mkdir my_video_flow $ docker run \ --runtime=nvidia \ --rm \ --mount "type=bind,source=$PWD/my_video,target=/input" \ --mount "type=bind,source=$PWD/my_video_flow,target=/output" \ --mount "type=bind,source=$HOME/.nv,target=/cache/nv" \ willprice/furnari-flow \ img_%06d.jpg $ ls my_video_flow u v $ ls my_video_flow/u img_0000001.jpg img_0000002.jpg ...
Details
The software assumes that all video frames have been extracted in a directory. Files should be named according to some pattern, e.g., img_%07d.jpg
. The software will put flow files in the same directory using a provided filename pattern, e.g., flow_%s_%07d.jpg
, where the %s will be subsituted with "x" for the x flows and "y" for the y flows. For example, if DIR is a directory containing 4 images:
DIR:
img_0000001.jpg
img_0000002.jpg
img_0000003.jpg
img_0000004.jpg
the command compute_flow DIR img_%07d.jpg flow_%s_%07d.jpg
will read the images in order and compute optical flows. The content of DIR will be as follows after the execution of the command:
DIR:
img_0000001.jpg
img_0000002.jpg
img_0000003.jpg
img_0000004.jpg
flow_x_0000001.jpg
flow_x_0000002.jpg
flow_x_0000003.jpg
flow_x_0000004.jpg
flow_y_0000001.jpg
flow_y_0000002.jpg
flow_y_0000003.jpg
flow_y_0000004.jpg
where flow_x_{n}.jpg
is the x flow computed between img_{n}.jpg
and img_{n+1}.jpg
(if no dilation is used - see help).
Build
You only need to build this software if you intend on tweaking the source, otherwise you should just use the pre-built docker images.
Dependencies:
Installation
First, build opencv with gpu support. To do so, download opencv 2.4.x sources from https://opencv.org/releases.html. Unzip the downloaded archive, then enter the opencv folder and issue the following commands:
mkdir build
cd build
cmake -DCUDA_USE_STATIC_CUDA_RUNTIME=OFF ..
(inspect theDockerfile
for further flags that might be of use)make -j $(nproc)
Then clone the current repository and enter the compute_flow_video
folder. Type:
export OpenCV_DIR=path_to_opencv_build_directory
mkdir build
cd build
cmake -DCUDA_USE_STATIC_CUDA_RUNTIME=OFF ..
make -j $(nproc)