Theora-1.0

Theora.Encoding

Contents

Theora structures and function
Ogg-related functions

Description

This module calls the libtheora C library to generate video ogg files from YCbCr images. As explained on http://theora.org/doc/libtheora-1.0/group__encfuncs.html, the basic steps for creating a video are the following :

create in an Info record
call encodeAlloc on it
call flushHeader until it returns Nothing
For each uncompressed frame, submit it with encodeIn, then retrieve potential packets with encodeOut

Synopsis

Theora structures and function

data Info Source

Constructors

Info
Fields frameWidth :: Int32 frameHeight :: Int32 picWidth :: Int32 picHeight :: Int32 picX :: Int32 picY :: Int32 colorSpace :: ColorSpace pixelFmt :: PixelFmt targetBitRate :: CInt quality :: CInt keyframeGranuleShift :: CInt

Instances

data Comment Source

Constructors

Comment
Fields user :: [String] Your comments vendor :: String Name of the encoder, i.e. your application

Instances

Storable Comment

data PixelFmt Source

Theora supports 4 different pixel formats, listed in http://theora.org/doc/Theora.pdf. YCbCr chroma frames (Cb and Cr) may be resized for compression (see http://en.wikipedia.org/Ycbcr). The resulting pixel formats are as follows :

Constructors

Pf420	Chroma decimation by 2 in both directions
Pf422	Chroma decimation by 2 in the x direction
Pf444	No chroma decimation

Instances

data ColorSpace Source

Constructors

Unspecified
ItuRec470M	A color space designed for NTSC content
ItuRec470BG	A color space designed for PAL/SECAM content

Instances

Enum ColorSpace

encodeAlloc :: Info -> IO (Maybe EncCtx)Source

Makes an encoder (EncCtx) instance out of an Info record

flushHeader :: EncCtx -> Comment -> IO [OggPacket]Source

Returns the last header packets. This function should be called before encoding actual video.

data ImgPlane Source

Instances

Storable ImgPlane

data YCbCrBuffer Source

YCbCrBuffer is the type of raw YCbCr frames

Constructors

YCbCr
Fields y :: ImgPlane the Y plane cb :: ImgPlane the Cb plane cr :: ImgPlane the Cr plane

Instances

Storable YCbCrBuffer

newYCbCr :: Int -> Int -> PixelFmt -> IO YCbCrBuffer Source

Allocate a new YCbCrBuffer object

encodeIn :: EncCtx -> YCbCrBuffer -> IO ()Source

Submits a frame for encoding

encodeOut :: EncCtx -> Bool -> IO [OggPacket]Source

Retrieve all the ready encoded packets

Ogg-related functions

data OggPacket Source

Instances

Storable OggPacket

newOggStreamState :: Int -> IO OggStreamStateSource

Initializes an Ogg container stream

data OggPage Source

Instances

Show OggPage
Storable OggPage

streamPacketIn :: OggStreamState -> OggPacket -> IO ()Source

Submits an encoded packet into the streams

streamPageOut :: OggStreamState -> IO (Maybe OggPage)Source

Get an outputable Ogg page

streamFlush :: OggStreamState -> IO (Maybe OggPage)Source

Retrieve the last pages of the stream