Classes | Defines | Typedefs | Enumerations

codec.h File Reference

The shared libtheoradec and libtheoraenc C API. More...

#include <ogg/ogg.h>
Include dependency graph for theora/codec.h:
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Classes

struct  th_img_plane
 A buffer for a single color plane in an uncompressed image. More...
struct  th_info
 Theora bitstream information. More...
struct  th_comment
 The comment information. More...
struct  th_quant_ranges
 A set of qi ranges. More...
struct  th_quant_info
 A complete set of quantization parameters. More...
struct  th_huff_code
 A Huffman code for a Theora DCT token. More...

Defines

#define _O_THEORA_CODEC_H_   (1)
#define TH_NHUFFMAN_TABLES   (80)
 The number of Huffman tables used by Theora.
#define TH_NDCT_TOKENS   (32)
 The number of DCT token values in each table.
Return codes

#define TH_EFAULT   (-1)
 An invalid pointer was provided.
#define TH_EINVAL   (-10)
 An invalid argument was provided.
#define TH_EBADHEADER   (-20)
 The contents of the header were incomplete, invalid, or unexpected.
#define TH_ENOTFORMAT   (-21)
 The header does not belong to a Theora stream.
#define TH_EVERSION   (-22)
 The bitstream version is too high.
#define TH_EIMPL   (-23)
 The specified function is not implemented.
#define TH_EBADPACKET   (-24)
 There were errors in the video data packet.
#define TH_DUPFRAME   (1)
 The decoded packet represented a dropped frame.

Typedefs

typedef th_img_plane th_ycbcr_buffer [3]
 A complete image buffer for an uncompressed frame.
typedef struct th_comment th_comment
 The comment information.
typedef unsigned char th_quant_base [64]
 A single base matrix.

Enumerations

enum  th_colorspace { TH_CS_UNSPECIFIED, TH_CS_ITU_REC_470M, TH_CS_ITU_REC_470BG, TH_CS_NSPACES }
 

The currently defined color space tags.

More...
enum  th_pixel_fmt {
  TH_PF_420, TH_PF_RSVD, TH_PF_422, TH_PF_444,
  TH_PF_NFORMATS
}
 

The currently defined pixel format tags.

More...

Functions

Basic shared functions

const char * th_version_string (void)
 Retrieves a human-readable string to identify the library vendor and version.
ogg_uint32_t th_version_number (void)
 Retrieves the library version number.
ogg_int64_t th_granule_frame (void *_encdec, ogg_int64_t _granpos)
 Converts a granule position to an absolute frame index, starting at 0.
double th_granule_time (void *_encdec, ogg_int64_t _granpos)
 Converts a granule position to an absolute time in seconds.
int th_packet_isheader (ogg_packet *_op)
 Determines whether a Theora packet is a header or not.
int th_packet_iskeyframe (ogg_packet *_op)
 Determines whether a theora packet is a key frame or not.
Functions for manipulating header data

void th_info_init (th_info *_info)
 Initializes a th_info structure.
void th_info_clear (th_info *_info)
 Clears a th_info structure.
void th_comment_init (th_comment *_tc)
 Initialize a th_comment structure.
void th_comment_add (th_comment *_tc, char *_comment)
 Add a comment to an initialized th_comment structure.
void th_comment_add_tag (th_comment *_tc, char *_tag, char *_val)
 Add a comment to an initialized th_comment structure.
char * th_comment_query (th_comment *_tc, char *_tag, int _count)
 Look up a comment value by its tag.
int th_comment_query_count (th_comment *_tc, char *_tag)
 Look up the number of instances of a tag.
void th_comment_clear (th_comment *_tc)
 Clears a th_comment structure.

Detailed Description

The shared libtheoradec and libtheoraenc C API.

You don't need to include this directly.


Define Documentation

#define _O_THEORA_CODEC_H_   (1)
#define TH_DUPFRAME   (1)

The decoded packet represented a dropped frame.

The player can continue to display the current frame, as the contents of the decoded frame buffer have not changed.

#define TH_EBADHEADER   (-20)

The contents of the header were incomplete, invalid, or unexpected.

#define TH_EBADPACKET   (-24)

There were errors in the video data packet.

#define TH_EFAULT   (-1)

An invalid pointer was provided.

#define TH_EIMPL   (-23)

The specified function is not implemented.

#define TH_EINVAL   (-10)

An invalid argument was provided.

#define TH_ENOTFORMAT   (-21)

The header does not belong to a Theora stream.

#define TH_EVERSION   (-22)

The bitstream version is too high.

#define TH_NDCT_TOKENS   (32)

The number of DCT token values in each table.

#define TH_NHUFFMAN_TABLES   (80)

The number of Huffman tables used by Theora.


Typedef Documentation

typedef struct th_comment th_comment

The comment information.

This structure holds the in-stream metadata corresponding to the 'comment' header packet. The comment header is meant to be used much like someone jotting a quick note on the label of a video. It should be a short, to the point text note that can be more than a couple words, but not more than a short paragraph.

The metadata is stored as a series of (tag, value) pairs, in length-encoded string vectors. The first occurrence of the '=' character delimits the tag and value. A particular tag may occur more than once, and order is significant. The character set encoding for the strings is always UTF-8, but the tag names are limited to ASCII, and treated as case-insensitive. See the Theora specification, Section 6.3.3 for details.

In filling in this structure, th_decode_headerin() will null-terminate the user_comment strings for safety. However, the bitstream format itself treats them as 8-bit clean vectors, possibly containing null characters, and so the length array should be treated as their authoritative length.

typedef unsigned char th_quant_base[64]

A single base matrix.

A complete image buffer for an uncompressed frame.

The chroma planes may be decimated by a factor of two in either direction, as indicated by th_info::pixel_fmt. The width and height of the Y' plane must be multiples of 16. They may need to be cropped for display, using the rectangle specified by th_info::pic_x, th_info::pic_y, th_info::pic_width, and th_info::pic_height. All samples are 8 bits.

Note:
The term YUV often used to describe a colorspace is ambiguous. The exact parameters of the RGB to YUV conversion process aside, in many contexts the U and V channels actually have opposite meanings. To avoid this confusion, we are explicit: the name of the color channels are Y'CbCr, and they appear in that order, always. The prime symbol denotes that the Y channel is non-linear. Cb and Cr stand for "Chroma blue" and "Chroma red", respectively.

Enumeration Type Documentation

The currently defined color space tags.

See the Theora specification, Chapter 4, for exact details on the meaning of each of these color spaces.

Enumerator:
TH_CS_UNSPECIFIED 

The color space was not specified at the encoder.

It may be conveyed by an external means.

TH_CS_ITU_REC_470M 

A color space designed for NTSC content.

TH_CS_ITU_REC_470BG 

A color space designed for PAL/SECAM content.

TH_CS_NSPACES 

The total number of currently defined color spaces.

The currently defined pixel format tags.

See the Theora specification, Section 4.4, for details on the precise sample locations.

Enumerator:
TH_PF_420 

Chroma decimation by 2 in both the X and Y directions (4:2:0).

The Cb and Cr chroma planes are half the width and half the height of the luma plane.

TH_PF_RSVD 

Currently reserved.

TH_PF_422 

Chroma decimation by 2 in the X direction (4:2:2).

The Cb and Cr chroma planes are half the width of the luma plane, but full height.

TH_PF_444 

No chroma decimation (4:4:4).

The Cb and Cr chroma planes are full width and full height.

TH_PF_NFORMATS 

The total number of currently defined pixel formats.