Safe Haskell	Safe-Inferred
Language	GHC2021

Codec.EBML

Contents

WebM decoder
Raw EBML decoder
EBML stream reader
EBML data types
EBML schema data types
Helpers
Low-level API, mostly for testing

Description

This module is intended to be imported qualified:

import qualified Codec.EBML as EBML

Decode a webm file with:

EBML.decodeWebMFile "path/file.webm"

Split a webm stream segments with:

let streamReader = EBML.newStreamReader
buf <- acquire data
EBML.feedReader buf streamReader

References:

EBML specification introduction: https://matroska-org.github.io/libebml/specs.html
Document layout: https://www.matroska.org/technical/diagram.html
The matroska schema: https://github.com/ietf-wg-cellar/matroska-specification/blob/master/ebml_matroska.xml
The matroska schema doc: https://www.matroska.org/technical/elements.html
The webm guidelines: https://www.webmproject.org/docs/container/
The MSE byte stream format spec: https://w3c.github.io/media-source/index.html#byte-stream-format-specs
The MSE byte stream format for webm: https://w3c.github.io/mse-byte-stream-format-webm/

Synopsis

decodeWebM :: ByteString -> Either Text WebMDocument
data WebMDocument = WebMDocument {
- timestampScale :: Word64
- clusters :: [WebMCluster]
}
data WebMCluster = WebMCluster {
- timestamp :: Word64
- content :: [EBMLElement]
}
decodeEBMLDocument :: [EBMLSchema] -> ByteString -> Either Text EBMLDocument
webmSchemas :: [EBMLSchema]
data StreamReader
newStreamReader :: StreamReader
data StreamFrame = StreamFrame {
- initialization :: ByteString
- media :: ByteString
}
feedReader :: ByteString -> StreamReader -> Either Text (Maybe StreamFrame, StreamReader)
newtype EBMLDocument = EBMLDocument [EBMLElement]
data EBMLElement = EBMLElement {
- header :: EBMLElementHeader
- value :: EBMLValue
}
data EBMLValue
- = EBMLRoot [EBMLElement]
- | EBMLSignedInteger Int64
- | EBMLUnsignedInteger Word64
- | EBMLFloat Double
- | EBMLText Text
- | EBMLDate Text
- | EBMLBinary ByteString
data EBMLElementHeader = EBMLElementHeader {
- eid :: EBMLID
- size :: Maybe Word64
}
newtype EBMLID = EBMLID Word32
data EBMLSchema = EBMLSchema {
- name :: Text
- eid :: EBMLID
- decode :: EBMLSchemas -> EBMLElementHeader -> Get EBMLValue
}
decodeEBMLFile :: [EBMLSchema] -> FilePath -> IO (Either Text EBMLDocument)
decodeWebMFile :: FilePath -> IO (Either Text WebMDocument)
prettyEBMLDocument :: [EBMLSchema] -> EBMLDocument -> Text
data EBMLSchemas
compileSchemas :: [EBMLSchema] -> EBMLSchemas
getDocument :: EBMLSchemas -> Get EBMLDocument
getElementHeader :: Get EBMLElementHeader
getElementID :: Get EBMLID
getDataSize :: Get Word64
getElement :: EBMLSchemas -> Get EBMLElement

WebM decoder

decodeWebM :: ByteString -> Either Text WebMDocument Source #

Lazy decode a WebMDocument.

data WebMDocument Source #

A WebM document.

Constructors

WebMDocument
Fields timestampScale :: Word64 Base unit for Segment Ticks and Track Ticks, in nanoseconds. A TimestampScale of 1_000_000 means segments' timestamps are expressed in milliseconds; clusters :: [WebMCluster] The list of clusters.

data WebMCluster Source #

A WebM cluster, e.g. a media segment.

Constructors

WebMCluster
Fields timestamp :: Word64 Absolute timestamp of the cluster. content :: [EBMLElement] The cluster elements.

Raw EBML decoder

decodeEBMLDocument :: [EBMLSchema] -> ByteString -> Either Text EBMLDocument Source #

Lazy decode a EBMLDocument.

webmSchemas :: [EBMLSchema] Source #

The webm document schemas.

EBML stream reader

data StreamReader Source #

Create a stream reader with newStreamReader, and decode media segments with feedReader.

newStreamReader :: StreamReader Source #

Initialize a stream reader.

data StreamFrame Source #

A valid frame that can be served.

Constructors

StreamFrame
Fields initialization :: ByteString The initialization segments, to be provided before the first media segment. media :: ByteString The begining of the last media segment found in the input buffer.

feedReader :: ByteString -> StreamReader -> Either Text (Maybe StreamFrame, StreamReader) Source #

Feed data into a stream reader. Returns either an error, or maybe a new StreamFrame and an updated StreamReader.

EBML data types

newtype EBMLDocument Source #

EBML document structure, including the Header and Body Root.

Constructors

EBMLDocument [EBMLElement]

data EBMLElement Source #

EBML element.

Constructors

EBMLElement
Fields header :: EBMLElementHeader value :: EBMLValue

Instances

Instances details

Show EBMLElement Source #
Instance details Defined in Codec.EBML.Element Methods showsPrec :: Int -> EBMLElement -> ShowS # show :: EBMLElement -> String # showList :: [EBMLElement] -> ShowS #
Eq EBMLElement Source #
Instance details Defined in Codec.EBML.Element Methods (==) :: EBMLElement -> EBMLElement -> Bool # (/=) :: EBMLElement -> EBMLElement -> Bool #

data EBMLValue Source #

EBML element value.

Constructors

EBMLRoot [EBMLElement]
EBMLSignedInteger Int64
EBMLUnsignedInteger Word64
EBMLFloat Double
EBMLText Text
EBMLDate Text
EBMLBinary ByteString

Instances

Instances details

Show EBMLValue Source #
Instance details Defined in Codec.EBML.Element Methods showsPrec :: Int -> EBMLValue -> ShowS # show :: EBMLValue -> String # showList :: [EBMLValue] -> ShowS #
Eq EBMLValue Source #
Instance details Defined in Codec.EBML.Element Methods (==) :: EBMLValue -> EBMLValue -> Bool # (/=) :: EBMLValue -> EBMLValue -> Bool #

data EBMLElementHeader Source #

EBML element header.

Constructors

EBMLElementHeader
Fields eid :: EBMLID size :: Maybe Word64 size is Nothing for unknown-sized element.

Instances

Instances details

Show EBMLElementHeader Source #
Instance details Defined in Codec.EBML.Element Methods showsPrec :: Int -> EBMLElementHeader -> ShowS # show :: EBMLElementHeader -> String # showList :: [EBMLElementHeader] -> ShowS #
Eq EBMLElementHeader Source #
Instance details Defined in Codec.EBML.Element Methods (==) :: EBMLElementHeader -> EBMLElementHeader -> Bool # (/=) :: EBMLElementHeader -> EBMLElementHeader -> Bool #

newtype EBMLID Source #

EBML element id.

Constructors

EBMLID Word32

Instances

Instances details

Num EBMLID Source #
Instance details Defined in Codec.EBML.Element Methods (+) :: EBMLID -> EBMLID -> EBMLID # (-) :: EBMLID -> EBMLID -> EBMLID # (*) :: EBMLID -> EBMLID -> EBMLID # negate :: EBMLID -> EBMLID # abs :: EBMLID -> EBMLID # signum :: EBMLID -> EBMLID # fromInteger :: Integer -> EBMLID #
Show EBMLID Source #
Instance details Defined in Codec.EBML.Element Methods showsPrec :: Int -> EBMLID -> ShowS # show :: EBMLID -> String # showList :: [EBMLID] -> ShowS #
Eq EBMLID Source #
Instance details Defined in Codec.EBML.Element Methods (==) :: EBMLID -> EBMLID -> Bool # (/=) :: EBMLID -> EBMLID -> Bool #
Ord EBMLID Source #
Instance details Defined in Codec.EBML.Element Methods compare :: EBMLID -> EBMLID -> Ordering # (<) :: EBMLID -> EBMLID -> Bool # (<=) :: EBMLID -> EBMLID -> Bool # (>) :: EBMLID -> EBMLID -> Bool # (>=) :: EBMLID -> EBMLID -> Bool # max :: EBMLID -> EBMLID -> EBMLID # min :: EBMLID -> EBMLID -> EBMLID #

EBML schema data types

data EBMLSchema Source #

EBML schema definition.

Note that this is missing:

min/max occurrence constraint.
default value.
element path.

Constructors

EBMLSchema
Fields name :: Text The element name. eid :: EBMLID The element id. decode :: EBMLSchemas -> EBMLElementHeader -> Get EBMLValue How to decode the element value.

Helpers

decodeEBMLFile :: [EBMLSchema] -> FilePath -> IO (Either Text EBMLDocument) Source #

Decode a raw EBML file.

decodeWebMFile :: FilePath -> IO (Either Text WebMDocument) Source #

Decode a webm file.

prettyEBMLDocument :: [EBMLSchema] -> EBMLDocument -> Text Source #

Pretty-print a EBMLDocument.

Low-level API, mostly for testing

data EBMLSchemas Source #

compileSchemas :: [EBMLSchema] -> EBMLSchemas Source #

Combine a list of schema for decoder.

getDocument :: EBMLSchemas -> Get EBMLDocument Source #

getElementHeader :: Get EBMLElementHeader Source #

getElementID :: Get EBMLID Source #

getDataSize :: Get Word64 Source #

getElement :: EBMLSchemas -> Get EBMLElement Source #