Classes | Files | Defines | Typedefs | Enumerations | Functions

Encoder Algorithm Interface
[Common Algorithm Interface]

Collaboration diagram for Encoder Algorithm Interface:

Classes

struct  vpx_fixed_buf
 Generic fixed size buffer structure. More...
struct  vpx_codec_cx_pkt
 Encoder output packet. More...
struct  vpx_rational
 Rational Number. More...
struct  vpx_codec_enc_cfg
 Encoder configuration structure. More...

Files

file  vpx_encoder.h
 

Describes the encoder algorithm interface to applications.


Defines

#define VPX_ENCODER_ABI_VERSION
 Current ABI version number.
#define VPX_CODEC_CAP_PSNR   0x10000
 Encoder capabilities bitfield.
#define VPX_CODEC_USE_PSNR   0x10000
 Initialization-time Feature Enabling.
#define VPX_FRAME_IS_KEY   0x1
 frame is the start of a GOP
#define VPX_FRAME_IS_DROPPABLE   0x2
 frame can be dropped without affecting the stream (no future frame depends on this one)
#define VPX_FRAME_IS_INVISIBLE   0x4
 frame should be decoded but will not be shown
#define VPX_EFLAG_FORCE_KF   (1<<0)
 Force this frame to be a keyframe.
#define vpx_codec_enc_init(ctx, iface, cfg, flags)   vpx_codec_enc_init_ver(ctx, iface, cfg, flags, VPX_ENCODER_ABI_VERSION)
 Convenience macro for vpx_codec_enc_init_ver().
#define VPX_DL_REALTIME   (1)
 deadline parameter analogous to VPx REALTIME mode.
#define VPX_DL_GOOD_QUALITY   (1000000)
 deadline parameter analogous to VPx GOOD QUALITY mode.
#define VPX_DL_BEST_QUALITY   (0)
 deadline parameter analogous to VPx BEST QUALITY mode.

Typedefs

typedef struct vpx_fixed_buf vpx_fixed_buf_t
 Generic fixed size buffer structure.
typedef int64_t vpx_codec_pts_t
 Time Stamp Type.
typedef uint32_t vpx_codec_frame_flags_t
 Compressed Frame Flags.
typedef struct vpx_codec_cx_pkt vpx_codec_cx_pkt_t
 Encoder output packet.
typedef struct vpx_rational vpx_rational_t
 Rational Number.
typedef long vpx_enc_frame_flags_t
 Encoded Frame Flags.
typedef struct vpx_codec_enc_cfg vpx_codec_enc_cfg_t
 Encoder configuration structure.

Enumerations

enum  vpx_codec_cx_pkt_kind { VPX_CODEC_CX_FRAME_PKT, VPX_CODEC_STATS_PKT, VPX_CODEC_PSNR_PKT, VPX_CODEC_CUSTOM_PKT = 256 }
 

Encoder output packet variants.

More...
enum  vpx_enc_pass { VPX_RC_ONE_PASS, VPX_RC_FIRST_PASS, VPX_RC_LAST_PASS }
 

Multi-pass Encoding Pass.

More...
enum  vpx_rc_mode { VPX_VBR, VPX_CBR }
 

Rate control mode.

More...
enum  vpx_kf_mode { VPX_KF_FIXED, VPX_KF_AUTO, VPX_KF_DISABLED = 0 }
 

Keyframe placement mode.

More...

Functions

vpx_codec_err_t vpx_codec_enc_init_ver (vpx_codec_ctx_t *ctx, vpx_codec_iface_t *iface, vpx_codec_enc_cfg_t *cfg, vpx_codec_flags_t flags, int ver)
 Initialize an encoder instance.
vpx_codec_err_t vpx_codec_enc_config_default (vpx_codec_iface_t *iface, vpx_codec_enc_cfg_t *cfg, unsigned int usage)
 Get a default configuration.
vpx_codec_err_t vpx_codec_enc_config_set (vpx_codec_ctx_t *ctx, const vpx_codec_enc_cfg_t *cfg)
 Set or change configuration.
vpx_fixed_buf_tvpx_codec_get_global_headers (vpx_codec_ctx_t *ctx)
 Get global stream headers.
vpx_codec_err_t vpx_codec_encode (vpx_codec_ctx_t *ctx, const vpx_image_t *img, vpx_codec_pts_t pts, unsigned long duration, vpx_enc_frame_flags_t flags, unsigned long deadline)
 Encode a frame.
vpx_codec_err_t vpx_codec_set_cx_data_buf (vpx_codec_ctx_t *ctx, const vpx_fixed_buf_t *buf, unsigned int pad_before, unsigned int pad_after)
 Set compressed data output buffer.
const vpx_codec_cx_pkt_tvpx_codec_get_cx_data (vpx_codec_ctx_t *ctx, vpx_codec_iter_t *iter)
 Encoded data iterator.
const vpx_image_tvpx_codec_get_preview_frame (vpx_codec_ctx_t *ctx)
 Get Preview Frame.

Detailed Description

This abstraction allows applications using this encoder to easily support multiple video formats with minimal code duplication. This section describes the interface common to all encoders.


Define Documentation

#define VPX_CODEC_CAP_PSNR   0x10000

Encoder capabilities bitfield.

Each encoder advertises the capabilities it supports as part of its vpx_codec_iface_t interface structure. Capabilities are extra interfaces or functionality, and are not required to be supported by an encoder.

The available flags are specifiedby VPX_CODEC_CAP_* defines. Can issue PSNR packets

#define vpx_codec_enc_init (   ctx,
  iface,
  cfg,
  flags 
)    vpx_codec_enc_init_ver(ctx, iface, cfg, flags, VPX_ENCODER_ABI_VERSION)

Convenience macro for vpx_codec_enc_init_ver().

Ensures the ABI version parameter is properly set.

#define VPX_CODEC_USE_PSNR   0x10000

Initialization-time Feature Enabling.

Certain codec features must be known at initialization time, to allow for proper memory allocation.

The available flags are specified by VPX_CODEC_USE_* defines. Calculate PSNR on each frame

#define VPX_DL_BEST_QUALITY   (0)

deadline parameter analogous to VPx BEST QUALITY mode.

#define VPX_DL_GOOD_QUALITY   (1000000)

deadline parameter analogous to VPx GOOD QUALITY mode.

#define VPX_DL_REALTIME   (1)

deadline parameter analogous to VPx REALTIME mode.

#define VPX_EFLAG_FORCE_KF   (1<<0)

Force this frame to be a keyframe.

#define VPX_ENCODER_ABI_VERSION

Current ABI version number.

#define VPX_FRAME_IS_DROPPABLE   0x2

frame can be dropped without affecting the stream (no future frame depends on this one)

#define VPX_FRAME_IS_INVISIBLE   0x4

frame should be decoded but will not be shown

#define VPX_FRAME_IS_KEY   0x1

frame is the start of a GOP


Typedef Documentation

Encoder output packet.

This structure contains the different kinds of output data the encoder may produce while compressing a frame. alias for struct vpx_codec_cx_pkt

Encoder configuration structure.

This structure contains the encoder settings that have common representations across all codecs. This doesn't imply that all codecs support all features, however. alias for struct vpx_codec_enc_cfg

typedef uint32_t vpx_codec_frame_flags_t

Compressed Frame Flags.

This type represents a bitfield containing information about a compressed frame that may be useful to an application. The most significant 16 bits can be used by an algorithm to provide additional detail, for example to support frame types that are codec specific (MPEG-1 D-frames for example)

typedef int64_t vpx_codec_pts_t

Time Stamp Type.

An integer, which when multiplied by the stream's time base, provides the absolute time of a sample.

typedef long vpx_enc_frame_flags_t

Encoded Frame Flags.

This type indicates a bitfield to be passed to vpx_codec_encode(), defining per-frame boolean values. By convention, bits common to all codecs will be named VPX_EFLAG_*, and bits specific to an algorithm will be named /algo/_eflag_*. The lower order 16 bits are reserved for common use.

Generic fixed size buffer structure.

This structure is able to hold a reference to any fixed size buffer. alias for struct vpx_fixed_buf

typedef struct vpx_rational vpx_rational_t

Rational Number.

This structure holds a fractional value. alias for struct vpx_rational


Enumeration Type Documentation

Encoder output packet variants.

This enumeration lists the different kinds of data packets that can be returned by calls to vpx_codec_get_cx_data(). Algorithms MAY extend this list to provide additional functionality.

Enumerator:
VPX_CODEC_CX_FRAME_PKT 

Compressed video frame.

VPX_CODEC_STATS_PKT 

Two-pass statistics for this frame.

VPX_CODEC_PSNR_PKT 

PSNR statistics for this frame.

VPX_CODEC_CUSTOM_PKT 

Algorithm extensions.

Multi-pass Encoding Pass.

Enumerator:
VPX_RC_ONE_PASS 

Single pass mode.

VPX_RC_FIRST_PASS 

First pass of multi-pass mode.

VPX_RC_LAST_PASS 

Final pass of multi-pass mode.

Keyframe placement mode.

This enumeration determines whether keyframes are placed automatically by the encoder or whether this behavior is disabled. Older releases of this SDK were implemented such that VPX_KF_FIXED meant keyframes were disabled. This name is confusing for this behavior, so the new symbols to be used are VPX_KF_AUTO and VPX_KF_DISABLED.

Enumerator:
VPX_KF_FIXED 

deprecated, implies VPX_KF_DISABLED

VPX_KF_AUTO 

Encoder determines optimal placement automatically.

VPX_KF_DISABLED 

Encoder does not place keyframes.

Rate control mode.

Enumerator:
VPX_VBR 

Variable Bit Rate (VBR) mode.

VPX_CBR 

Constant Bit Rate (CBR) mode.


Function Documentation

vpx_codec_err_t vpx_codec_enc_config_default ( vpx_codec_iface_t iface,
vpx_codec_enc_cfg_t cfg,
unsigned int  usage 
)

Get a default configuration.

Initializes a encoder configuration structure with default values. Supports the notion of "usages" so that an algorithm may offer different default settings depending on the user's intended goal. This function SHOULD be called by all applications to initialize the configuration structure before specializing the configuration with application specific values.

Parameters:
[in] iface Pointer to the algorithm interface to use.
[out] cfg Configuration buffer to populate
[in] usage End usage. Set to 0 or use codec specific values.
Return values:
VPX_CODEC_OK The configuration was populated.
VPX_CODEC_INCAPABLE Interface is not an encoder interface.
VPX_CODEC_INVALID_PARAM A parameter was NULL, or the usage value was not recognized.
vpx_codec_err_t vpx_codec_enc_config_set ( vpx_codec_ctx_t ctx,
const vpx_codec_enc_cfg_t cfg 
)

Set or change configuration.

Reconfigures an encoder instance according to the given configuration.

Parameters:
[in] ctx Pointer to this instance's context
[in] cfg Configuration buffer to use
Return values:
VPX_CODEC_OK The configuration was populated.
VPX_CODEC_INCAPABLE Interface is not an encoder interface.
VPX_CODEC_INVALID_PARAM A parameter was NULL, or the usage value was not recognized.
vpx_codec_err_t vpx_codec_enc_init_ver ( vpx_codec_ctx_t ctx,
vpx_codec_iface_t iface,
vpx_codec_enc_cfg_t cfg,
vpx_codec_flags_t  flags,
int  ver 
)

Initialize an encoder instance.

Initializes a encoder context using the given interface. Applications should call the vpx_codec_enc_init convenience macro instead of this function directly, to ensure that the ABI version number parameter is properly initialized.

In XMA mode (activated by setting VPX_CODEC_USE_XMA in the flags parameter), the storage pointed to by the cfg parameter must be kept readable and stable until all memory maps have been set.

Parameters:
[in] ctx Pointer to this instance's context.
[in] iface Pointer to the algorithm interface to use.
[in] cfg Configuration to use, if known. May be NULL.
[in] flags Bitfield of VPX_CODEC_USE_* flags
[in] ver ABI version number. Must be set to VPX_ENCODER_ABI_VERSION
Return values:
VPX_CODEC_OK The decoder algorithm initialized.
VPX_CODEC_MEM_ERROR Memory allocation failed.
vpx_codec_err_t vpx_codec_encode ( vpx_codec_ctx_t ctx,
const vpx_image_t img,
vpx_codec_pts_t  pts,
unsigned long  duration,
vpx_enc_frame_flags_t  flags,
unsigned long  deadline 
)

Encode a frame.

Encodes a video frame at the given "presentation time." The presentation time stamp (PTS) MUST be strictly increasing.

The encoder supports the notion of a soft real-time deadline. Given a non-zero value to the deadline parameter, the encoder will make a "best effort" guarantee to return before the given time slice expires. It is implicit that limiting the available time to encode will degrade the output quality. The encoder can be given an unlimited time to produce the best possible frame by specifying a deadline of '0'. This deadline supercedes the VPx notion of "best quality, good quality, realtime". Applications that wish to map these former settings to the new deadline based system can use the symbols VPX_DL_REALTIME, VPX_DL_GOOD_QUALITY, and VPX_DL_BEST_QUALITY.

When the last frame has been passed to the encoder, this function should continue to be called, with the img parameter set to NULL. This will signal the end-of-stream condition to the encoder and allow it to encode any held buffers. Encoding is complete when vpx_codec_encode() is called and vpx_codec_get_cx_data() returns no data.

Parameters:
[in] ctx Pointer to this instance's context
[in] img Image data to encode, NULL to flush.
[in] pts Presentation time stamp, in timebase units.
[in] duration Duration to show frame, in timebase units.
[in] flags Flags to use for encoding this frame.
[in] deadline Time to spend encoding, in microseconds. (0=infinite)
Return values:
VPX_CODEC_OK The configuration was populated.
VPX_CODEC_INCAPABLE Interface is not an encoder interface.
VPX_CODEC_INVALID_PARAM A parameter was NULL, the image format is unsupported, etc.
const vpx_codec_cx_pkt_t* vpx_codec_get_cx_data ( vpx_codec_ctx_t ctx,
vpx_codec_iter_t iter 
)

Encoded data iterator.

Iterates over a list of data packets to be passed from the encoder to the application. The different kinds of packets available are enumerated in vpx_codec_cx_pkt_kind.

VPX_CODEC_CX_FRAME_PKT packets should be passed to the application's muxer. Multiple compressed frames may be in the list. VPX_CODEC_STATS_PKT packets should be appended to a global buffer.

The application MUST silently ignore any packet kinds that it does not recognize or support.

The data buffers returned from this function are only guaranteed to be valid until the application makes another call to any vpx_codec_* function.

Parameters:
[in] ctx Pointer to this instance's context
[in,out] iter Iterator storage, initialized to NULL
Returns:
Returns a pointer to an output data packet (compressed frame data, two-pass statistics, etc.) or NULL to signal end-of-list.
vpx_fixed_buf_t* vpx_codec_get_global_headers ( vpx_codec_ctx_t ctx  ) 

Get global stream headers.

Retrieves a stream level global header packet, if supported by the codec.

Parameters:
[in] ctx Pointer to this instance's context
Return values:
NULL Encoder does not support global header
Non-NULL Pointer to buffer containing global header packet
const vpx_image_t* vpx_codec_get_preview_frame ( vpx_codec_ctx_t ctx  ) 

Get Preview Frame.

Returns an image that can be used as a preview. Shows the image as it would exist at the decompressor. The application MUST NOT write into this image buffer.

Parameters:
[in] ctx Pointer to this instance's context
Returns:
Returns a pointer to a preview image, or NULL if no image is available.
vpx_codec_err_t vpx_codec_set_cx_data_buf ( vpx_codec_ctx_t ctx,
const vpx_fixed_buf_t buf,
unsigned int  pad_before,
unsigned int  pad_after 
)

Set compressed data output buffer.

Sets the buffer that the codec should output the compressed data into. This call effectively sets the buffer pointer returned in the next VPX_CODEC_CX_FRAME_PKT packet. Subsequent packets will be appended into this buffer. The buffer is preserved across frames, so applications must periodically call this function after flushing the accumulated compressed data to disk or to the network to reset the pointer to the buffer's head.

`pad_before` bytes will be skipped before writing the compressed data, and `pad_after` bytes will be appended to the packet. The size of the packet will be the sum of the size of the actual compressed data, pad_before, and pad_after. The padding bytes will be preserved (not overwritten).

Note that calling this function does not guarantee that the returned compressed data will be placed into the specified buffer. In the event that the encoded data will not fit into the buffer provided, the returned packet MAY point to an internal buffer, as it would if this call were never used. In this event, the output packet will NOT have any padding, and the application must free space and copy it to the proper place. This is of particular note in configurations that may output multiple packets for a single encoded frame (e.g., lagged encoding) or if the application does not reset the buffer periodically.

Applications may restore the default behavior of the codec providing the compressed data buffer by calling this function with a NULL buffer.

Applications MUSTNOT call this function during iteration of vpx_codec_get_cx_data().

Parameters:
[in] ctx Pointer to this instance's context
[in] buf Buffer to store compressed data into
[in] pad_before Bytes to skip before writing compressed data
[in] pad_after Bytes to skip after writing compressed data
Return values:
VPX_CODEC_OK The buffer was set successfully.
VPX_CODEC_INVALID_PARAM A parameter was NULL, the image format is unsupported, etc.