theora.h

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/********************************************************************
 *                                                                  *
 * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE.   *
 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
 *                                                                  *
 * THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2003                *
 * by the Xiph.Org Foundation http://www.xiph.org/                  *
 *                                                                  *
 ********************************************************************

  function:
  last mod: $Id: theora.h,v 1.17 2003/12/06 18:06:19 arc Exp $

 ********************************************************************/

#ifndef _O_THEORA_H_
#define _O_THEORA_H_

#ifdef __cplusplus
extern "C"
{
#endif /* __cplusplus */

#ifndef LIBOGG2
#include <ogg/ogg.h>
#else
#include <ogg2/ogg.h>
/* This is temporary until libogg2 is more complete */
ogg_buffer_state *ogg_buffer_create(void);
#endif

/** \mainpage
 * 
 * \section intro Introduction
 *
 * This is the documentation for the libtheora C API.
 * libtheora is the reference implementation for
 * <a href="http://www.theora.org/">Theora</a>, a free video codec.
 * Theora is derived from On2's VP3 codec with improved integration for
 * Ogg multimedia formats by <a href="http://www.xiph.org/">Xiph.Org</a>.
 */

/** \file
 * The libtheora C API.
 */

/**
 * A YUV buffer for passing uncompressed frames to and from the codec.
 * This holds a Y'CbCr frame in planar format. The CbCr planes can be
 * subsampled and have their own separate dimensions and row stride
 * offsets. Note that the strides may be negative in some 
 * configurations. For theora the width and height of the largest plane
 * must be a multiple of 16. The actual meaningful picture size and 
 * offset are stored in the theora_info structure; frames returned by
 * the decoder may need to be cropped for display.
 *
 * All samples are 8 bits. Within each plane samples are ordered by
 * row from the top of the frame to the bottom. Within each row samples
 * are ordered from left to right.
 */
typedef struct {
    int   y_width;      /**< Width of the Y' luminance plane */
    int   y_height;     /**< Height of the luminance plane */
    int   y_stride;     /**< Offset in bytes between successive rows */

    int   uv_width;     /**< Height of the Cb and Cr chroma planes */
    int   uv_height;    /**< Width of the chroma planes */
    int   uv_stride;    /**< Offset between successive chroma rows */
    unsigned char *y;   /**< Pointer to start of luminance data */
    unsigned char *u;   /**< Pointer to start of Cb data */
    unsigned char *v;   /**< Pointer to start of Cr data */

} yuv_buffer;

/**
 * A Colorspace.
 */
typedef enum {
  OC_CS_UNSPECIFIED,    /**< The colorspace is unknown or unspecified */
  OC_CS_ITU_REC_470M,   /**< This is the best option for 'NTSC' content */
  OC_CS_ITU_REC_470BG,  /**< This is the best option for 'PAL' content */
  OC_CS_NSPACES         /**< This marks the end of the defined colorspaces */
} theora_colorspace;

/**
 * A Chroma subsampling
 *
 * These enumerate the available chroma subsampling options supported
 * by the theora format. See Section 4.4 of the specification for
 * exact definitions.
 */
typedef enum {
  OC_PF_420,    /**< Chroma subsampling by 2 in each direction (4:2:0) */
  OC_PF_RSVD,   /**< Reserved value */
  OC_PF_422,    /**< Horizonatal chroma subsampling by 2 (4:2:2) */
  OC_PF_444,    /**< No chroma subsampling at all (4:4:4) */
} theora_pixelformat;

/**
 * Theora bitstream info.
 * Contains the basic playback parameters for a stream,
 * corresponds to the initial 'info' header packet.
 * 
 * Encoded theora frames must be a multiple of 16 is size;
 * this is what the width and height members represent. To
 * handle other sizes, a crop rectangle is specified in 
 * frame_height and frame_width, offset_x and offset_y. The
 * offset and size should still be a multiple of 2 to avoid
 * chroma sampling shifts. Offset values in this structure
 * are measured from the  upper left of the image.
 *
 * Frame rate, in frames per second, is stored as a rational
 * fraction. So is the aspect ratio. Note that this refers
 * to the aspect ratio of the frame pixels, not of the
 * overall frame itself.
 * 
 * see the example code for use of the other parameters and
 * good default settings for the encoder parameters.
 */
typedef struct {
  ogg_uint32_t  width;		/**< encoded frame width  */
  ogg_uint32_t  height;		/**< encoded frame height */
  ogg_uint32_t  frame_width;	/**< display frame width  */
  ogg_uint32_t  frame_height;	/**< display frame height */
  ogg_uint32_t  offset_x;	/**< horizontal offset of the displayed frame */
  ogg_uint32_t  offset_y;	/**< vertical offset of the displayed frame */
  ogg_uint32_t  fps_numerator;	    /**< frame rate numerator **/
  ogg_uint32_t  fps_denominator;    /**< frame rate denominator **/
  ogg_uint32_t  aspect_numerator;   /**< pixel aspect ratio numerator */
  ogg_uint32_t  aspect_denominator; /**< pixel aspect ratio denominator */
  theora_colorspace colorspace;	    /**< colorspace */
  int           target_bitrate;	    /**< nominal bitrate in bits per second */
  int           quality;  /**< Nominal quality setting, 0-63 */
  int           quick_p;  /**< Quick encode/decode */

  /* decode only */
  unsigned char version_major;
  unsigned char version_minor;
  unsigned char version_subminor;

  void *codec_setup;

  /* encode only */
  int           dropframes_p;
  int           keyframe_auto_p;
  ogg_uint32_t  keyframe_frequency;
  ogg_uint32_t  keyframe_frequency_force;  /* also used for decode init to
                                              get granpos shift correct */
  ogg_uint32_t  keyframe_data_target_bitrate;
  ogg_int32_t   keyframe_auto_threshold;
  ogg_uint32_t  keyframe_mindistance;
  ogg_int32_t   noise_sensitivity;
  ogg_int32_t   sharpness;

  theora_pixelformat pixelformat;	/**< chroma subsampling mode to expect */

} theora_info;

/** Codec internal state and context.
 */
typedef struct{
  theora_info *i;
  ogg_int64_t granulepos;

  void *internal_encode;
  void *internal_decode;

} theora_state;

/** 
 * Comment header metadata.
 *
 * This structure holds the in-stream metadata corresponding to
 * the 'comment' header packet.
 *
 * Meta data is stored as a series of (tag, value) pairs, in
 * length-encoded string vectors. The first occurence of the 
 * '=' character delimits the tag and value. A particular tag
 * may occur more than once. The character set encoding for
 * the strings is always utf-8, but the tag names are limited
 * to case-insensitive ascii. See the spec for details.
 *
 * In filling in this structure, theora_decode_header() will
 * null-terminate the user_comment strings for safety. However,
 * the bitstream format itself treats them as 8-bit clean,
 * and so the length array should be treated as authoritative
 * for their length.
 */
typedef struct theora_comment{
  char **user_comments;         /**< An array of comment string vectors */
  int   *comment_lengths;       /**< An array of corresponding string vector lengths in bytes */
  int    comments;              /**< The total number of comment string vectors */
  char  *vendor;                /**< The vendor string identifying the encoder, null terminated */

} theora_comment;

#define OC_FAULT       -1       /**< General failure */
#define OC_EINVAL      -10      /**< Library encountered invalid internal data */
#define OC_DISABLED    -11      /**< Requested action is disabled */
#define OC_BADHEADER   -20      /**< Header packet was corrupt/invalid */
#define OC_NOTFORMAT   -21      /**< Packet is not a theora packet */
#define OC_VERSION     -22      /**< Bitstream version is not handled */
#define OC_IMPL        -23      /**< Feature or action not implemented */
#define OC_BADPACKET   -24      /**< Packet is corrupt */
#define OC_NEWPACKET   -25      /**< Packet is an (ignorable) unhandled extension */
#define OC_DUPFRAME    1        /**< Packet is a dropped frame */

/** 
 * Retrieve a human-readable string to identify the encoder vendor and version.
 * \returns A version string.
 */
extern const char *theora_version_string(void);

/**
 * Retrieve a 32-bit version number.
 * This number is composed of a 16-bit major version, 8-bit minor version
 * and 8 bit sub-version, composed as follows:
<pre>
   (VERSION_MAJOR<<16) + (VERSION_MINOR<<8) + (VERSION_SUB)
</pre>
* \returns The version number.
*/
extern ogg_uint32_t theora_version_number(void);

/**
 * Initialize the theora encoder.
 * \param th The theora_state handle to initialize for encoding.
 * \param ti A theora_info struct filled with the desired encoding parameters.
 * \retval 0 Success
 */
extern int theora_encode_init(theora_state *th, theora_info *ti);

/**
 * Submit a YUV buffer to the theora encoder.
 * \param t A theora_state handle previously initialized for encoding.
 * \param yuv A buffer of YUV data to encode.
 * \retval OC_EINVAL Encoder is not ready, or is finished.
 * \retval -1 The size of the given frame differs from those previously input
 * \retval 0 Success
 */
extern int theora_encode_YUVin(theora_state *t, yuv_buffer *yuv);

/**
 * Request the next packet of encoded video. 
 * The encoded data is placed in a user-provided ogg_packet structure.
 * \param t A theora_state handle previously initialized for encoding.
 * \param last_p whether this is the last packet the encoder should produce.
 * \param op An ogg_packet structure to fill. libtheora will set all
 *           elements of this structure, including a pointer to encoded
 *           data. The memory for the encoded data is owned by libtheora.
 * \retval 0 No internal storage exists OR no packet is ready
 * \retval -1 The encoding process has completed
 * \retval 1 Success
 */
extern int theora_encode_packetout( theora_state *t, int last_p,
                                    ogg_packet *op);

/**
 * Request a packet containing the initial header.
 * A pointer to the header data is placed in a user-provided ogg_packet
 * structure.
 * \param t A theora_state handle previously initialized for encoding.
 * \param op An ogg_packet structure to fill. libtheora will set all
 *           elements of this structure, including a pointer to the header
 *           data. The memory for the header data is owned by libtheora.
 * \retval 0 Success
 */
extern int theora_encode_header(theora_state *t, ogg_packet *op);