Decoder Algorithm Interface

Modules
	Frame-Based Decoding Functions
	Slice-Based Decoding Functions
	External Frame Buffer Functions

Files
file	vpx_decoder.h
	Describes the decoder algorithm interface to applications.

Data Structures
struct	vpx_codec_stream_info
	Stream properties. More...
struct	vpx_codec_dec_cfg
	Initialization Configurations. More...

Macros
#define	VPX_DECODER_ABI_VERSION
	Current ABI version number.
#define	VPX_CODEC_CAP_PUT_SLICE   0x10000
	Decoder capabilities bitfield. More...
#define	VPX_CODEC_CAP_PUT_FRAME   0x20000
#define	VPX_CODEC_CAP_POSTPROC   0x40000
#define	VPX_CODEC_CAP_ERROR_CONCEALMENT   0x80000
	Can conceal errors due to packet loss.
#define	VPX_CODEC_CAP_INPUT_FRAGMENTS   0x100000
	Can receive encoded frames one fragment at a time.
#define	VPX_CODEC_CAP_FRAME_THREADING   0x200000
	Initialization-time Feature Enabling. More...
#define	VPX_CODEC_CAP_EXTERNAL_FRAME_BUFFER   0x400000
#define	VPX_CODEC_USE_POSTPROC   0x10000
#define	VPX_CODEC_USE_ERROR_CONCEALMENT   0x20000
	Conceal errors in decoded frames.
#define	VPX_CODEC_USE_INPUT_FRAGMENTS   0x40000
	The input frame should be passed to the decoder one fragment at a time.
#define	VPX_CODEC_USE_FRAME_THREADING   0x80000
	Enable frame-based multi-threading.
#define	vpx_codec_dec_init(ctx, iface, cfg, flags)   vpx_codec_dec_init_ver(ctx, iface, cfg, flags, VPX_DECODER_ABI_VERSION)
	Convenience macro for vpx_codec_dec_init_ver() More...

Typedefs
typedef struct vpx_codec_stream_info	vpx_codec_stream_info_t
	Stream properties. More...
typedef struct vpx_codec_dec_cfg	vpx_codec_dec_cfg_t
	Initialization Configurations. More...

Functions
vpx_codec_err_t	vpx_codec_dec_init_ver (vpx_codec_ctx_t *ctx, vpx_codec_iface_t *iface, const vpx_codec_dec_cfg_t *cfg, vpx_codec_flags_t flags, int ver)
	Initialize a decoder instance. More...
vpx_codec_err_t	vpx_codec_peek_stream_info (vpx_codec_iface_t *iface, const uint8_t *data, unsigned int data_sz, vpx_codec_stream_info_t *si)
	Parse stream info from a buffer. More...
vpx_codec_err_t	vpx_codec_get_stream_info (vpx_codec_ctx_t *ctx, vpx_codec_stream_info_t *si)
	Return information about the current stream. More...
vpx_codec_err_t	vpx_codec_decode (vpx_codec_ctx_t *ctx, const uint8_t *data, unsigned int data_sz, void *user_priv, long deadline)
	Decode data. More...
vpx_image_t *	vpx_codec_get_frame (vpx_codec_ctx_t *ctx, vpx_codec_iter_t *iter)
	Decoded frames iterator. More...

Detailed Description

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

Macro Definition Documentation

VPX_CODEC_CAP_PUT_SLICE

#define VPX_CODEC_CAP_PUT_SLICE   0x10000

Decoder capabilities bitfield.

Each decoder 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 a decoder.

The available flags are specified by VPX_CODEC_CAP_* defines.Will issue put_slice callbacks

VPX_CODEC_CAP_PUT_FRAME

#define VPX_CODEC_CAP_PUT_FRAME   0x20000

Will issue put_frame callbacks

VPX_CODEC_CAP_POSTPROC

#define VPX_CODEC_CAP_POSTPROC   0x40000

Can postprocess decoded frame

VPX_CODEC_CAP_FRAME_THREADING

#define VPX_CODEC_CAP_FRAME_THREADING   0x200000

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.

Can support frame-based multi-threading

VPX_CODEC_CAP_EXTERNAL_FRAME_BUFFER

#define VPX_CODEC_CAP_EXTERNAL_FRAME_BUFFER   0x400000

brief Can support external frame buffers

VPX_CODEC_USE_POSTPROC

#define VPX_CODEC_USE_POSTPROC   0x10000

Postprocess decoded frame

vpx_codec_dec_init

#define vpx_codec_dec_init	(		ctx,
			iface,
			cfg,
			flags
	)		vpx_codec_dec_init_ver(ctx, iface, cfg, flags, VPX_DECODER_ABI_VERSION)

Convenience macro for vpx_codec_dec_init_ver()

Ensures the ABI version parameter is properly set.

Typedef Documentation

vpx_codec_stream_info_t

typedef struct vpx_codec_stream_info vpx_codec_stream_info_t

Stream properties.

This structure is used to query or set properties of the decoded stream. Algorithms may extend this structure with data specific to their bitstream by setting the sz member appropriately.

vpx_codec_dec_cfg_t

typedef struct vpx_codec_dec_cfg vpx_codec_dec_cfg_t

Initialization Configurations.

This structure is used to pass init time configuration options to the decoder.alias for struct vpx_codec_dec_cfg

Function Documentation

vpx_codec_dec_init_ver()

vpx_codec_err_t vpx_codec_dec_init_ver	(	vpx_codec_ctx_t *	ctx,
		vpx_codec_iface_t *	iface,
		const vpx_codec_dec_cfg_t *	cfg,
		vpx_codec_flags_t	flags,
		int	ver
	)

Initialize a decoder instance.

Initializes a decoder context using the given interface. Applications should call the vpx_codec_dec_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]	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_DECODER_ABI_VERSION

Return values

VPX_CODEC_OK	The decoder algorithm initialized.
VPX_CODEC_MEM_ERROR	Memory allocation failed.

vpx_codec_peek_stream_info()

vpx_codec_err_t vpx_codec_peek_stream_info	(	vpx_codec_iface_t *	iface,
		const uint8_t *	data,
		unsigned int	data_sz,
		vpx_codec_stream_info_t *	si
	)

Parse stream info from a buffer.

Performs high level parsing of the bitstream. Construction of a decoder context is not necessary. Can be used to determine if the bitstream is of the proper format, and to extract information from the stream.

Parameters

[in]	iface	Pointer to the algorithm interface
[in]	data	Pointer to a block of data to parse
[in]	data_sz	Size of the data buffer
[in,out]	si	Pointer to stream info to update. The size member MUST be properly initialized, but MAY be clobbered by the algorithm. This parameter MAY be NULL.

Return values

VPX_CODEC_OK

Bitstream is parsable and stream information updated

vpx_codec_get_stream_info()

vpx_codec_err_t vpx_codec_get_stream_info	(	vpx_codec_ctx_t *	ctx,
		vpx_codec_stream_info_t *	si
	)

Return information about the current stream.

Returns information about the stream that has been parsed during decoding.

Parameters

[in]	ctx	Pointer to this instance's context
[in,out]	si	Pointer to stream info to update. The size member MUST be properly initialized, but MAY be clobbered by the algorithm. This parameter MAY be NULL.

Return values

VPX_CODEC_OK

Bitstream is parsable and stream information updated

vpx_codec_decode()

vpx_codec_err_t vpx_codec_decode	(	vpx_codec_ctx_t *	ctx,
		const uint8_t *	data,
		unsigned int	data_sz,
		void *	user_priv,
		long	deadline
	)

Decode data.

Processes a buffer of coded data. If the processing results in a new decoded frame becoming available, PUT_SLICE and PUT_FRAME events may be generated, as appropriate. Encoded data MUST be passed in DTS (decode time stamp) order. Frames produced will always be in PTS (presentation time stamp) order. If the decoder is configured with VPX_CODEC_USE_INPUT_FRAGMENTS enabled, data and data_sz can contain a fragment of the encoded frame. Fragment #n must contain at least partition #n, but can also contain subsequent partitions (#n+1 - #n+i), and if so, fragments #n+1, .., #n+i must be empty. When no more data is available, this function should be called with NULL as data and 0 as data_sz. The memory passed to this function must be available until the frame has been decoded.

Parameters

[in]	ctx	Pointer to this instance's context
[in]	data	Pointer to this block of new coded data. If NULL, a VPX_CODEC_CB_PUT_FRAME event is posted for the previously decoded frame.
[in]	data_sz	Size of the coded data, in bytes.
[in]	user_priv	Application specific data to associate with this frame.
[in]	deadline	Soft deadline the decoder should attempt to meet, in us. Set to zero for unlimited.

Returns

Returns VPX_CODEC_OK if the coded data was processed completely and future pictures can be decoded without error. Otherwise, see the descriptions of the other error codes in vpx_codec_err_t for recoverability capabilities.

vpx_codec_get_frame()

vpx_image_t* vpx_codec_get_frame	(	vpx_codec_ctx_t *	ctx,
		vpx_codec_iter_t *	iter
	)

Decoded frames iterator.

Iterates over a list of the frames available for display. The iterator storage should be initialized to NULL to start the iteration. Iteration is complete when this function returns NULL.

The list of available frames becomes valid upon completion of the vpx_codec_decode call, and remains valid until the next call to vpx_codec_decode.

Parameters

[in]	ctx	Pointer to this instance's context
[in,out]	iter	Iterator storage, initialized to NULL

Returns

Returns a pointer to an image, if one is ready for display. Frames produced will always be in PTS (presentation time stamp) order.