`class Recordings`

Stores one WebM narration recording for each slide.

Recording paths mirror slide paths. For example, slides/020-topic/010-example.md is stored as audio/020-topic/010-example.webm.

Nested Classes and Modules

class Normalizer: Normalizes recording loudness using measured gain and peak limiting.
class TooLarge: Raised when an uploaded recording exceeds MAXIMUM_SIZE = 128 * 1024 * 1024.

Definitions

`CONTENT_TYPE = "audio/webm"`

The media type produced by the browser recorder.

`MAXIMUM_SIZE = 128 * 1024 * 1024`

The maximum accepted recording size (128 MiB).

`def initialize(root, maximum_size: MAXIMUM_SIZE)`

Initialize the recording store.

Signature

parameter　root　String: The directory where recordings are stored.
parameter　maximum_size　Integer: Maximum accepted recording size in bytes.

Implementation

def initialize(root, maximum_size: MAXIMUM_SIZE)
	@root = File.expand_path(root)
	@maximum_size = maximum_size
end

`attr :root`

Signature

attribute　String: The absolute recording root.

`def relative_path(slide)`

The recording path relative to #root for the given slide.

Signature

parameter　slide　Slide: The slide whose recording path is required.
returns　String

Implementation

def relative_path(slide)
	slide.path.sub(/\.md\z/, ".webm")
end

`def path(slide)`

The absolute recording path for the given slide.

Signature

parameter　slide　Slide: The slide whose recording path is required.
returns　String

Implementation

def path(slide)
	File.join(@root, relative_path(slide))
end

`def exist?(slide)`

Whether the slide has a recording.

Signature

parameter　slide　Slide: The slide to check.
returns　Boolean

Implementation

def exist?(slide)
	File.file?(path(slide))
end

`def read(slide)`

Open the recording as an HTTP body.

Signature

parameter　slide　Slide: The slide to read.
returns　Protocol::HTTP::Body::File | Nil

Implementation

def read(slide)
	if exist?(slide)
		Protocol::HTTP::Body::File.open(path(slide))
	end
end

`def write(slide, body)`

Write a recording atomically.

The request body is copied to a temporary file in the destination directory, then renamed over the existing recording only after the upload completes successfully.

Signature

parameter　slide　Slide: The slide being recorded.
parameter　body　Protocol::HTTP::Body::Readable: The uploaded recording.
returns　String: The absolute destination path.
raises　TooLarge: If the recording exceeds MAXIMUM_SIZE = 128 * 1024 * 1024.

Implementation

def write(slide, body)
	destination = path(slide)
	directory = File.dirname(destination)
	FileUtils.mkdir_p(directory)
	
	Tempfile.create(["presently-recording", ".webm"], directory, binmode: true) do |file|
		size = 0
		
		while chunk = body.read
			size += chunk.bytesize
			raise TooLarge, "Recording exceeds #{@maximum_size} bytes!" if size > @maximum_size
			
			file.write(chunk)
		end
		
		file.flush
		File.rename(file.path, destination)
	end
	
	return destination
end