AOMedia Codec SDK
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Encoder Algorithm Interface

Files

file  aom_encoder.h
 Describes the encoder algorithm interface to applications.
 

Data Structures

struct  aom_fixed_buf
 Generic fixed size buffer structure. More...
 
struct  aom_codec_cx_pkt
 Encoder output packet. More...
 
struct  aom_rational
 Rational Number. More...
 
struct  aom_codec_enc_cfg
 Encoder configuration structure. More...
 

Macros

#define AOM_ENCODER_ABI_VERSION
 Current ABI version number.
 
#define AOM_CODEC_CAP_PSNR   0x10000
 Encoder capabilities bitfield. More...
 
#define AOM_CODEC_CAP_OUTPUT_PARTITION   0x20000
 
#define AOM_CODEC_CAP_HIGHBITDEPTH   0x40000
 
#define AOM_CODEC_USE_PSNR   0x10000
 Initialization-time Feature Enabling. More...
 
#define AOM_CODEC_USE_OUTPUT_PARTITION   0x20000
 Make the encoder output one partition at a time.
 
#define AOM_CODEC_USE_HIGHBITDEPTH   0x40000
 
#define AOM_FRAME_IS_KEY   0x1
 
#define AOM_FRAME_IS_DROPPABLE   0x2
 frame can be dropped without affecting the stream (no future frame depends on this one)
 
#define AOM_FRAME_IS_INVISIBLE   0x4
 frame should be decoded but will not be shown
 
#define AOM_FRAME_IS_FRAGMENT   0x8
 this is a fragment of the encoded frame
 
#define AOM_ERROR_RESILIENT_DEFAULT   0x1
 Improve resiliency against losses of whole frames.
 
#define AOM_ERROR_RESILIENT_PARTITIONS   0x2
 The frame partitions are independently decodable by the bool decoder, meaning that partitions can be decoded even though earlier partitions have been lost. Note that intra prediction is still done over the partition boundary.
 
#define AOM_EFLAG_FORCE_KF   (1 << 0)
 
#define aom_codec_enc_init(ctx, iface, cfg, flags)   aom_codec_enc_init_ver(ctx, iface, cfg, flags, AOM_ENCODER_ABI_VERSION)
 Convenience macro for aom_codec_enc_init_ver() More...
 
#define aom_codec_enc_init_multi(ctx, iface, cfg, num_enc, flags, dsf)
 Convenience macro for aom_codec_enc_init_multi_ver() More...
 

Typedefs

typedef struct aom_fixed_buf aom_fixed_buf_t
 Generic fixed size buffer structure. More...
 
typedef int64_t aom_codec_pts_t
 Time Stamp Type. More...
 
typedef uint32_t aom_codec_frame_flags_t
 Compressed Frame Flags. More...
 
typedef uint32_t aom_codec_er_flags_t
 Error Resilient flags. More...
 
typedef struct aom_codec_cx_pkt aom_codec_cx_pkt_t
 Encoder output packet. More...
 
typedef struct aom_rational aom_rational_t
 Rational Number. More...
 
typedef long aom_enc_frame_flags_t
 Encoded Frame Flags. More...
 
typedef struct aom_codec_enc_cfg aom_codec_enc_cfg_t
 Encoder configuration structure. More...
 

Enumerations

enum  aom_codec_cx_pkt_kind {
  AOM_CODEC_CX_FRAME_PKT, AOM_CODEC_STATS_PKT, AOM_CODEC_FPMB_STATS_PKT, AOM_CODEC_PSNR_PKT,
  AOM_CODEC_CUSTOM_PKT = 256
}
 Encoder output packet variants. More...
 
enum  aom_enc_pass { AOM_RC_ONE_PASS, AOM_RC_FIRST_PASS, AOM_RC_LAST_PASS }
 Multi-pass Encoding Pass. More...
 
enum  aom_rc_mode { AOM_VBR, AOM_CBR, AOM_CQ, AOM_Q }
 Rate control mode. More...
 
enum  aom_kf_mode { AOM_KF_FIXED, AOM_KF_AUTO, AOM_KF_DISABLED = 0 }
 Keyframe placement mode. More...
 

Functions

aom_codec_err_t aom_codec_enc_init_ver (aom_codec_ctx_t *ctx, aom_codec_iface_t *iface, const aom_codec_enc_cfg_t *cfg, aom_codec_flags_t flags, int ver)
 Initialize an encoder instance. More...
 
aom_codec_err_t aom_codec_enc_init_multi_ver (aom_codec_ctx_t *ctx, aom_codec_iface_t *iface, aom_codec_enc_cfg_t *cfg, int num_enc, aom_codec_flags_t flags, aom_rational_t *dsf, int ver)
 Initialize multi-encoder instance. More...
 
aom_codec_err_t aom_codec_enc_config_default (aom_codec_iface_t *iface, aom_codec_enc_cfg_t *cfg, unsigned int reserved)
 Get a default configuration. More...
 
aom_codec_err_t aom_codec_enc_config_set (aom_codec_ctx_t *ctx, const aom_codec_enc_cfg_t *cfg)
 Set or change configuration. More...
 
aom_fixed_buf_taom_codec_get_global_headers (aom_codec_ctx_t *ctx)
 Get global stream headers. More...
 
aom_codec_err_t aom_codec_encode (aom_codec_ctx_t *ctx, const aom_image_t *img, aom_codec_pts_t pts, unsigned long duration, aom_enc_frame_flags_t flags)
 Encode a frame. More...
 
aom_codec_err_t aom_codec_set_cx_data_buf (aom_codec_ctx_t *ctx, const aom_fixed_buf_t *buf, unsigned int pad_before, unsigned int pad_after)
 Set compressed data output buffer. More...
 
const aom_codec_cx_pkt_taom_codec_get_cx_data (aom_codec_ctx_t *ctx, aom_codec_iter_t *iter)
 Encoded data iterator. More...
 
const aom_image_taom_codec_get_preview_frame (aom_codec_ctx_t *ctx)
 Get Preview Frame. More...
 

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.

Macro Definition Documentation

#define AOM_CODEC_CAP_PSNR   0x10000

Encoder capabilities bitfield.

Each encoder advertises the capabilities it supports as part of its aom_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 specified by AOM_CODEC_CAP_* defines.Can issue PSNR packets

#define AOM_CODEC_CAP_OUTPUT_PARTITION   0x20000

Can output one partition at a time. Each partition is returned in its own AOM_CODEC_CX_FRAME_PKT, with the FRAME_IS_FRAGMENT flag set for every partition but the last. In this mode all frames are always returned partition by partition.

#define AOM_CODEC_CAP_HIGHBITDEPTH   0x40000

Can support input images at greater than 8 bitdepth.

#define AOM_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 AOM_CODEC_USE_* defines.Calculate PSNR on each frame

#define AOM_CODEC_USE_HIGHBITDEPTH   0x40000

Use high bitdepth

#define AOM_FRAME_IS_KEY   0x1

frame is the start of a GOP

#define AOM_EFLAG_FORCE_KF   (1 << 0)

Force this frame to be a keyframe

#define aom_codec_enc_init (   ctx,
  iface,
  cfg,
  flags 
)    aom_codec_enc_init_ver(ctx, iface, cfg, flags, AOM_ENCODER_ABI_VERSION)

Convenience macro for aom_codec_enc_init_ver()

Ensures the ABI version parameter is properly set.

#define aom_codec_enc_init_multi (   ctx,
  iface,
  cfg,
  num_enc,
  flags,
  dsf 
)
Value:
aom_codec_enc_init_multi_ver(ctx, iface, cfg, num_enc, flags, dsf, \
#define AOM_ENCODER_ABI_VERSION
Current ABI version number.
Definition: aom_encoder.h:43
aom_codec_err_t aom_codec_enc_init_multi_ver(aom_codec_ctx_t *ctx, aom_codec_iface_t *iface, aom_codec_enc_cfg_t *cfg, int num_enc, aom_codec_flags_t flags, aom_rational_t *dsf, int ver)
Initialize multi-encoder instance.

Convenience macro for aom_codec_enc_init_multi_ver()

Ensures the ABI version parameter is properly set.

Typedef Documentation

Generic fixed size buffer structure.

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

typedef int64_t aom_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 uint32_t aom_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 uint32_t aom_codec_er_flags_t

Error Resilient flags.

These flags define which error resilient features to enable in the encoder. The flags are specified through the aom_codec_enc_cfg::g_error_resilient variable.

Encoder output packet.

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

typedef struct aom_rational aom_rational_t

Rational Number.

This structure holds a fractional value.alias for struct aom_rational

typedef long aom_enc_frame_flags_t

Encoded Frame Flags.

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

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 aom_codec_enc_cfg

Enumeration Type Documentation

Encoder output packet variants.

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

Enumerator
AOM_CODEC_CX_FRAME_PKT 

Compressed video frame

AOM_CODEC_STATS_PKT 

Two-pass statistics for this frame

AOM_CODEC_FPMB_STATS_PKT 

first pass mb statistics for this frame

AOM_CODEC_PSNR_PKT 

PSNR statistics for this frame

AOM_CODEC_CUSTOM_PKT 

Algorithm extensions

Multi-pass Encoding Pass.

Enumerator
AOM_RC_ONE_PASS 

Single pass mode

AOM_RC_FIRST_PASS 

First pass of multi-pass mode

AOM_RC_LAST_PASS 

Final pass of multi-pass mode

Rate control mode.

Enumerator
AOM_VBR 

Variable Bit Rate (VBR) mode

AOM_CBR 

Constant Bit Rate (CBR) mode

AOM_CQ 

Constrained Quality (CQ) mode

AOM_Q 

Constant Quality (Q) 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 AOM_KF_FIXED meant keyframes were disabled. This name is confusing for this behavior, so the new symbols to be used are AOM_KF_AUTO and AOM_KF_DISABLED.

Enumerator
AOM_KF_FIXED 

deprecated, implies AOM_KF_DISABLED

AOM_KF_AUTO 

Encoder determines optimal placement automatically

AOM_KF_DISABLED 

Encoder does not place keyframes.

Function Documentation

aom_codec_err_t aom_codec_enc_init_ver ( aom_codec_ctx_t ctx,
aom_codec_iface_t iface,
const aom_codec_enc_cfg_t cfg,
aom_codec_flags_t  flags,
int  ver 
)

Initialize an encoder instance.

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

If the library was configured with –disable-multithread, this call is not thread safe and should be guarded with a lock if being used in a multithreaded context.

Parameters
[in]ctxPointer to this instance's context.
[in]ifacePointer to the algorithm interface to use.
[in]cfgConfiguration to use, if known.
[in]flagsBitfield of AOM_CODEC_USE_* flags
[in]verABI version number. Must be set to AOM_ENCODER_ABI_VERSION
Return values
AOM_CODEC_OKThe decoder algorithm initialized.
AOM_CODEC_MEM_ERRORMemory allocation failed.
aom_codec_err_t aom_codec_enc_init_multi_ver ( aom_codec_ctx_t ctx,
aom_codec_iface_t iface,
aom_codec_enc_cfg_t cfg,
int  num_enc,
aom_codec_flags_t  flags,
aom_rational_t dsf,
int  ver 
)

Initialize multi-encoder instance.

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

Parameters
[in]ctxPointer to this instance's context.
[in]ifacePointer to the algorithm interface to use.
[in]cfgConfiguration to use, if known.
[in]num_encTotal number of encoders.
[in]flagsBitfield of AOM_CODEC_USE_* flags
[in]dsfPointer to down-sampling factors.
[in]verABI version number. Must be set to AOM_ENCODER_ABI_VERSION
Return values
AOM_CODEC_OKThe decoder algorithm initialized.
AOM_CODEC_MEM_ERRORMemory allocation failed.
aom_codec_err_t aom_codec_enc_config_default ( aom_codec_iface_t iface,
aom_codec_enc_cfg_t cfg,
unsigned int  reserved 
)

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]ifacePointer to the algorithm interface to use.
[out]cfgConfiguration buffer to populate.
[in]reservedMust set to 0.
Return values
AOM_CODEC_OKThe configuration was populated.
AOM_CODEC_INCAPABLEInterface is not an encoder interface.
AOM_CODEC_INVALID_PARAMA parameter was NULL, or the usage value was not recognized.
aom_codec_err_t aom_codec_enc_config_set ( aom_codec_ctx_t ctx,
const aom_codec_enc_cfg_t cfg 
)

Set or change configuration.

Reconfigures an encoder instance according to the given configuration.

Parameters
[in]ctxPointer to this instance's context
[in]cfgConfiguration buffer to use
Return values
AOM_CODEC_OKThe configuration was populated.
AOM_CODEC_INCAPABLEInterface is not an encoder interface.
AOM_CODEC_INVALID_PARAMA parameter was NULL, or the usage value was not recognized.
aom_fixed_buf_t* aom_codec_get_global_headers ( aom_codec_ctx_t ctx)

Get global stream headers.

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

Parameters
[in]ctxPointer to this instance's context
Return values
NULLEncoder does not support global header
Non-NULLPointer to buffer containing global header packet
aom_codec_err_t aom_codec_encode ( aom_codec_ctx_t ctx,
const aom_image_t img,
aom_codec_pts_t  pts,
unsigned long  duration,
aom_enc_frame_flags_t  flags 
)

Encode a frame.

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

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 aom_codec_encode() is called and aom_codec_get_cx_data() returns no data.

Parameters
[in]ctxPointer to this instance's context
[in]imgImage data to encode, NULL to flush.
[in]ptsPresentation time stamp, in timebase units.
[in]durationDuration to show frame, in timebase units.
[in]flagsFlags to use for encoding this frame.
Return values
AOM_CODEC_OKThe configuration was populated.
AOM_CODEC_INCAPABLEInterface is not an encoder interface.
AOM_CODEC_INVALID_PARAMA parameter was NULL, the image format is unsupported, etc.
aom_codec_err_t aom_codec_set_cx_data_buf ( aom_codec_ctx_t ctx,
const aom_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 AOM_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 MUST NOT call this function during iteration of aom_codec_get_cx_data().

Parameters
[in]ctxPointer to this instance's context
[in]bufBuffer to store compressed data into
[in]pad_beforeBytes to skip before writing compressed data
[in]pad_afterBytes to skip after writing compressed data
Return values
AOM_CODEC_OKThe buffer was set successfully.
AOM_CODEC_INVALID_PARAMA parameter was NULL, the image format is unsupported, etc.
const aom_codec_cx_pkt_t* aom_codec_get_cx_data ( aom_codec_ctx_t ctx,
aom_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 aom_codec_cx_pkt_kind.

AOM_CODEC_CX_FRAME_PKT packets should be passed to the application's muxer. Multiple compressed frames may be in the list. AOM_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 aom_codec_* function.

Parameters
[in]ctxPointer to this instance's context
[in,out]iterIterator 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.
const aom_image_t* aom_codec_get_preview_frame ( aom_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]ctxPointer to this instance's context
Returns
Returns a pointer to a preview image, or NULL if no image is available.