116 lines
3.4 KiB
Ruby
116 lines
3.4 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
require "shellwords"
|
|
|
|
# A wrapper for the ffmpeg command.
|
|
class FFmpeg
|
|
extend Memoist
|
|
|
|
class Error < StandardError; end
|
|
|
|
attr_reader :file
|
|
|
|
# Operate on a file with FFmpeg.
|
|
# @param file [File, String] a webm, mp4, gif, or apng file
|
|
def initialize(file)
|
|
@file = file.is_a?(String) ? File.open(file) : file
|
|
end
|
|
|
|
# Generate a .png preview image for a video or animation. Generates
|
|
# thumbnails intelligently by avoiding blank frames.
|
|
#
|
|
# @return [MediaFile] the preview image
|
|
def smart_video_preview
|
|
vp = Tempfile.new(["video-preview", ".png"], binmode: true)
|
|
|
|
# https://ffmpeg.org/ffmpeg.html#Main-options
|
|
# https://ffmpeg.org/ffmpeg-filters.html#thumbnail
|
|
output = shell!("ffmpeg -i #{file.path.shellescape} -vf thumbnail=300 -frames:v 1 -y #{vp.path.shellescape}")
|
|
Rails.logger.debug(output)
|
|
|
|
MediaFile.open(vp)
|
|
end
|
|
|
|
# Get file metadata using ffprobe.
|
|
# @see https://ffmpeg.org/ffprobe.html
|
|
# @see https://gist.github.com/nrk/2286511
|
|
# @return [Hash] a hash of the file's metadata
|
|
def metadata
|
|
output = shell!("ffprobe -v quiet -print_format json -show_format -show_streams #{file.path.shellescape}")
|
|
json = JSON.parse(output)
|
|
json.with_indifferent_access
|
|
end
|
|
|
|
def width
|
|
video_streams.first[:width]
|
|
end
|
|
|
|
def height
|
|
video_streams.first[:height]
|
|
end
|
|
|
|
# @see https://trac.ffmpeg.org/wiki/FFprobeTips#Duration
|
|
# @return [Float, nil] The duration of the video or animation in seconds, or nil if unknown.
|
|
def duration
|
|
if metadata.dig(:format, :duration).present?
|
|
metadata.dig(:format, :duration).to_f
|
|
elsif playback_info.has_key?(:time)
|
|
hours, minutes, seconds = playback_info[:time].split(/:/)
|
|
hours.to_f*60*60 + minutes.to_f*60 + seconds.to_f
|
|
else
|
|
nil
|
|
end
|
|
end
|
|
|
|
# @return [Integer, nil] The number of frames in the video or animation, or nil if unknown.
|
|
def frame_count
|
|
if video_streams.first.has_key?(:nb_frames)
|
|
video_streams.first[:nb_frames].to_i
|
|
elsif playback_info.has_key?(:frame)
|
|
playback_info[:frame].to_i
|
|
else
|
|
nil
|
|
end
|
|
end
|
|
|
|
# @return [Float, nil] The average frame rate of the video or animation, or nil if unknown.
|
|
def frame_rate
|
|
return nil if frame_count.nil? || duration.nil? || duration == 0
|
|
frame_count / duration
|
|
end
|
|
|
|
def video_streams
|
|
metadata[:streams].select { |stream| stream[:codec_type] == "video" }
|
|
end
|
|
|
|
def audio_streams
|
|
metadata[:streams].select { |stream| stream[:codec_type] == "audio" }
|
|
end
|
|
|
|
def has_audio?
|
|
audio_streams.present?
|
|
end
|
|
|
|
# Decode the full video and return a hash containing the frame count, fps, and runtime.
|
|
def playback_info
|
|
output = shell!("ffmpeg -i #{file.path.shellescape} -f null /dev/null")
|
|
status_line = output.lines.grep(/\Aframe=/).first.chomp
|
|
|
|
# status_line = "frame= 10 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.48 bitrate=N/A speed= 179x"
|
|
# info = {"frame"=>"10", "fps"=>"0.0", "q"=>"-0.0", "Lsize"=>"N/A", "time"=>"00:00:00.48", "bitrate"=>"N/A", "speed"=>"188x"}
|
|
info = status_line.scan(/\S+=\s*\S+/).map { |pair| pair.split(/=\s*/) }.to_h
|
|
info.with_indifferent_access
|
|
rescue Error => e
|
|
{}
|
|
end
|
|
|
|
def shell!(command)
|
|
program = command.shellsplit.first
|
|
output, status = Open3.capture2e(command)
|
|
raise Error, "#{program} failed: #{output}" if !status.success?
|
|
output
|
|
end
|
|
|
|
memoize :metadata, :playback_info, :frame_count, :duration
|
|
end
|