I would like to use Phoenix LiveView Uploads to store server-side files of type video, image and audio. I would like to avoid integrating a javascript file uploader
LiveView Uploads provides size
metadata, but I also need width
, height
and duration
metadata from one or all of those file types.
Following is an example Phoenix.LiveView.UploadEntry
struct:
%Phoenix.LiveView.UploadEntry{cancelled?: false, client_last_modified: nil, client_name: "activated_eye_2.png", client_size: 403494, client_type: "image/png", done?: true, preflighted?: true, progress: 100, ref: "0", upload_config: :avatar, upload_ref: "phx-FwYTESCSIgs1LwLB", uuid: "36ec0b28-cae5-45c0-a2cf-6d3d2c1f3919", valid?: true}
It appears that the uploaded file metadata is limited to last_modified
, name
, size
and type
What would need to be done to also be able to examine width
, height
and duration
metadata from a file uploaded using Phoenix LiveView Uploads?
The easiest way would be to handle all this in the consume stage with some external tool like ffprobe (from ffmpeg).
def handle_event("save", _params, socket) do
uploaded_files =
consume_uploaded_entries(socket, :avatar, fn %{path: path}, _entry ->
dest =
Path.join([:code.priv_dir(:my_app), "static", "uploads", "#{Path.basename(path)}.mp4"])
File.cp!(path, dest)
# getting the duration with ffprobe
{time_in_seconds, _error} = System.cmd("ffprobe", [
"-i",
dest,
"-v",
"quiet",
"-show_entries",
"format=duration",
"-hide_banner",
"-of",
"default=noprint_wrappers=1:nokey=1"
])
# printing the duration
IO.inspect(time_in_seconds, label: "Duration")
{:ok, Routes.static_path(socket, "/uploads/#{Path.basename(dest)}")}
end)
{:noreply, update(socket, :uploaded_files, &(&1 ++ uploaded_files))}
end
To do it during the upload you probably will need to hook up to websocket and get the data directly from the binary data that is sent through the wire.
To be honest I don’t even know if that’s possible, let’s hope that someone more knowledgeable than me can chime in, but that’s so over the top that that’s a solution that I would only look for if the requirements are so rigid that there’s no other way to do it.
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In Javascript, you can process that metadata in the loadedmetadata
event handler during a file upload. In theory, you could use Hooks
and a Javascript uploader in app.js
, but I don’t think you’d be able to use the LiveView Uploads feature.
I’ll use this approach if all else fails
The ffmpex
module provides a wrapper for the FFmpeg
library, giving access to FFprobe
Overview — ffmpex v0.10.0 (hexdocs.pm)
FFprobe.duration("/path/to/input.mp4")
# => result in seconds, e.g., 228.456939
Using your System.cmd/3
example, I was able to figure out how to retrieve metadata
from audio
, video
and image
files while consuming the files from the uploader.
I learned that the mediainfo
library retrieves image
metadata better than ffprobe
, and was able to retrieve metadata for all 3 file types using mediainfo
I had a problem with mediainfo
when integrating it with the System.cmd/3 because the cmd line format requires double quote characters around an attribute value. When used in the System.cmd/3
format, those value double quote characters need to be removed.
Cmd line width extraction from image file
mediainfo /filepath --Inform="Image;%Width%"
System.cmd/3 width extraction from image file
{width, _error} = System.cmd("mediainfo", [
dest,
"--Inform=Image;%Width%"
])
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