2 * Copyright (c) 2010 The WebM project authors. All Rights Reserved.
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
12 /*!\defgroup encoder Encoder Algorithm Interface
14 * This abstraction allows applications using this encoder to easily support
15 * multiple video formats with minimal code duplication. This section describes
16 * the interface common to all encoders.
21 * \brief Describes the encoder algorithm interface to applications.
23 * This file describes the interface between an application and a
24 * video encoder algorithm.
33 #include "vpx_codec.h"
36 /*!\brief Current ABI version number
39 * If this file is altered in any way that changes the ABI, this value
40 * must be bumped. Examples include, but are not limited to, changing
41 * types, removing or reassigning enums, adding/removing/rearranging
42 * fields to structures
44 #define VPX_ENCODER_ABI_VERSION (2 + VPX_CODEC_ABI_VERSION) /**<\hideinitializer*/
47 /*! \brief Encoder capabilities bitfield
49 * Each encoder advertises the capabilities it supports as part of its
50 * ::vpx_codec_iface_t interface structure. Capabilities are extra
51 * interfaces or functionality, and are not required to be supported
54 * The available flags are specified by VPX_CODEC_CAP_* defines.
56 #define VPX_CODEC_CAP_PSNR 0x10000 /**< Can issue PSNR packets */
59 /*! \brief Initialization-time Feature Enabling
61 * Certain codec features must be known at initialization time, to allow
62 * for proper memory allocation.
64 * The available flags are specified by VPX_CODEC_USE_* defines.
66 #define VPX_CODEC_USE_PSNR 0x10000 /**< Calculate PSNR on each frame */
69 /*!\brief Generic fixed size buffer structure
71 * This structure is able to hold a reference to any fixed size buffer.
73 typedef struct vpx_fixed_buf
75 void *buf; /**< Pointer to the data */
76 size_t sz; /**< Length of the buffer, in chars */
77 } vpx_fixed_buf_t; /**< alias for struct vpx_fixed_buf */
80 /*!\brief Time Stamp Type
82 * An integer, which when multiplied by the stream's time base, provides
83 * the absolute time of a sample.
85 typedef int64_t vpx_codec_pts_t;
88 /*!\brief Compressed Frame Flags
90 * This type represents a bitfield containing information about a compressed
91 * frame that may be useful to an application. The most significant 16 bits
92 * can be used by an algorithm to provide additional detail, for example to
93 * support frame types that are codec specific (MPEG-1 D-frames for example)
95 typedef uint32_t vpx_codec_frame_flags_t;
96 #define VPX_FRAME_IS_KEY 0x1 /**< frame is the start of a GOP */
97 #define VPX_FRAME_IS_DROPPABLE 0x2 /**< frame can be dropped without affecting
98 the stream (no future frame depends on
100 #define VPX_FRAME_IS_INVISIBLE 0x4 /**< frame should be decoded but will not
104 /*!\brief Encoder output packet variants
106 * This enumeration lists the different kinds of data packets that can be
107 * returned by calls to vpx_codec_get_cx_data(). Algorithms \ref MAY
108 * extend this list to provide additional functionality.
110 enum vpx_codec_cx_pkt_kind
112 VPX_CODEC_CX_FRAME_PKT, /**< Compressed video frame */
113 VPX_CODEC_STATS_PKT, /**< Two-pass statistics for this frame */
114 VPX_CODEC_PSNR_PKT, /**< PSNR statistics for this frame */
115 VPX_CODEC_CUSTOM_PKT = 256 /**< Algorithm extensions */
119 /*!\brief Encoder output packet
121 * This structure contains the different kinds of output data the encoder
122 * may produce while compressing a frame.
124 typedef struct vpx_codec_cx_pkt
126 enum vpx_codec_cx_pkt_kind kind; /**< packet variant */
131 void *buf; /**< compressed data buffer */
132 size_t sz; /**< length of compressed data */
133 vpx_codec_pts_t pts; /**< time stamp to show frame
134 (in timebase units) */
135 unsigned long duration; /**< duration to show frame
136 (in timebase units) */
137 vpx_codec_frame_flags_t flags; /**< flags for this frame */
138 } frame; /**< data for compressed frame packet */
139 struct vpx_fixed_buf twopass_stats; /**< data for two-pass packet */
142 unsigned int samples[4]; /**< Number of samples, total/y/u/v */
143 uint64_t sse[4]; /**< sum squared error, total/y/u/v */
144 double psnr[4]; /**< PSNR, total/y/u/v */
145 } psnr; /**< data for PSNR packet */
146 struct vpx_fixed_buf raw; /**< data for arbitrary packets */
148 /* This packet size is fixed to allow codecs to extend this
149 * interface without having to manage storage for raw packets,
150 * i.e., if it's smaller than 128 bytes, you can store in the
151 * packet list directly.
153 char pad[128 - sizeof(enum vpx_codec_cx_pkt_kind)]; /**< fixed sz */
154 } data; /**< packet data */
155 } vpx_codec_cx_pkt_t; /**< alias for struct vpx_codec_cx_pkt */
158 /*!\brief Rational Number
160 * This structure holds a fractional value.
162 typedef struct vpx_rational
164 int num; /**< fraction numerator */
165 int den; /**< fraction denominator */
166 } vpx_rational_t; /**< alias for struct vpx_rational */
169 /*!\brief Multi-pass Encoding Pass */
172 VPX_RC_ONE_PASS, /**< Single pass mode */
173 VPX_RC_FIRST_PASS, /**< First pass of multi-pass mode */
174 VPX_RC_LAST_PASS /**< Final pass of multi-pass mode */
178 /*!\brief Rate control mode */
181 VPX_VBR, /**< Variable Bit Rate (VBR) mode */
182 VPX_CBR, /**< Constant Bit Rate (CBR) mode */
183 VPX_CQ /**< Constant Quality (CQ) mode */
187 /*!\brief Keyframe placement mode.
189 * This enumeration determines whether keyframes are placed automatically by
190 * the encoder or whether this behavior is disabled. Older releases of this
191 * SDK were implemented such that VPX_KF_FIXED meant keyframes were disabled.
192 * This name is confusing for this behavior, so the new symbols to be used
193 * are VPX_KF_AUTO and VPX_KF_DISABLED.
197 VPX_KF_FIXED, /**< deprecated, implies VPX_KF_DISABLED */
198 VPX_KF_AUTO, /**< Encoder determines optimal placement automatically */
199 VPX_KF_DISABLED = 0 /**< Encoder does not place keyframes. */
203 /*!\brief Encoded Frame Flags
205 * This type indicates a bitfield to be passed to vpx_codec_encode(), defining
206 * per-frame boolean values. By convention, bits common to all codecs will be
207 * named VPX_EFLAG_*, and bits specific to an algorithm will be named
208 * /algo/_eflag_*. The lower order 16 bits are reserved for common use.
210 typedef long vpx_enc_frame_flags_t;
211 #define VPX_EFLAG_FORCE_KF (1<<0) /**< Force this frame to be a keyframe */
214 /*!\brief Encoder configuration structure
216 * This structure contains the encoder settings that have common representations
217 * across all codecs. This doesn't imply that all codecs support all features,
220 typedef struct vpx_codec_enc_cfg
223 * generic settings (g)
226 /*!\brief Algorithm specific "usage" value
228 * Algorithms may define multiple values for usage, which may convey the
229 * intent of how the application intends to use the stream. If this value
230 * is non-zero, consult the documentation for the codec to determine its
233 unsigned int g_usage;
236 /*!\brief Maximum number of threads to use
238 * For multi-threaded implementations, use no more than this number of
239 * threads. The codec may use fewer threads than allowed. The value
240 * 0 is equivalent to the value 1.
242 unsigned int g_threads;
245 /*!\brief Bitstream profile to use
247 * Some codecs support a notion of multiple bitstream profiles. Typically
248 * this maps to a set of features that are turned on or off. Often the
249 * profile to use is determined by the features of the intended decoder.
250 * Consult the documentation for the codec to determine the valid values
251 * for this parameter, or set to zero for a sane default.
253 unsigned int g_profile; /**< profile of bitstream to use */
257 /*!\brief Width of the frame
259 * This value identifies the presentation resolution of the frame,
260 * in pixels. Note that the frames passed as input to the encoder must
261 * have this resolution. Frames will be presented by the decoder in this
262 * resolution, independent of any spatial resampling the encoder may do.
267 /*!\brief Height of the frame
269 * This value identifies the presentation resolution of the frame,
270 * in pixels. Note that the frames passed as input to the encoder must
271 * have this resolution. Frames will be presented by the decoder in this
272 * resolution, independent of any spatial resampling the encoder may do.
277 /*!\brief Stream timebase units
279 * Indicates the smallest interval of time, in seconds, used by the stream.
280 * For fixed frame rate material, or variable frame rate material where
281 * frames are timed at a multiple of a given clock (ex: video capture),
282 * the \ref RECOMMENDED method is to set the timebase to the reciprocal
283 * of the frame rate (ex: 1001/30000 for 29.970 Hz NTSC). This allows the
284 * pts to correspond to the frame number, which can be handy. For
285 * re-encoding video from containers with absolute time timestamps, the
286 * \ref RECOMMENDED method is to set the timebase to that of the parent
287 * container or multimedia framework (ex: 1/1000 for ms, as in FLV).
289 struct vpx_rational g_timebase;
292 /*!\brief Enable error resilient mode.
294 * Error resilient mode indicates to the encoder that it should take
295 * measures appropriate for streaming over lossy or noisy links, if
296 * possible. Set to 1 to enable this feature, 0 to disable it.
298 unsigned int g_error_resilient;
301 /*!\brief Multi-pass Encoding Mode
303 * This value should be set to the current phase for multi-pass encoding.
304 * For single pass, set to #VPX_RC_ONE_PASS.
306 enum vpx_enc_pass g_pass;
309 /*!\brief Allow lagged encoding
311 * If set, this value allows the encoder to consume a number of input
312 * frames before producing output frames. This allows the encoder to
313 * base decisions for the current frame on future frames. This does
314 * increase the latency of the encoding pipeline, so it is not appropriate
315 * in all situations (ex: realtime encoding).
317 * Note that this is a maximum value -- the encoder may produce frames
318 * sooner than the given limit. Set this value to 0 to disable this
321 unsigned int g_lag_in_frames;
325 * rate control settings (rc)
328 /*!\brief Temporal resampling configuration, if supported by the codec.
330 * Temporal resampling allows the codec to "drop" frames as a strategy to
331 * meet its target data rate. This can cause temporal discontinuities in
332 * the encoded video, which may appear as stuttering during playback. This
333 * trade-off is often acceptable, but for many applications is not. It can
334 * be disabled in these cases.
336 * Note that not all codecs support this feature. All vpx VPx codecs do.
337 * For other codecs, consult the documentation for that algorithm.
339 * This threshold is described as a percentage of the target data buffer.
340 * When the data buffer falls below this percentage of fullness, a
341 * dropped frame is indicated. Set the threshold to zero (0) to disable
344 unsigned int rc_dropframe_thresh;
347 /*!\brief Enable/disable spatial resampling, if supported by the codec.
349 * Spatial resampling allows the codec to compress a lower resolution
350 * version of the frame, which is then upscaled by the encoder to the
351 * correct presentation resolution. This increases visual quality at
352 * low data rates, at the expense of CPU time on the encoder/decoder.
354 unsigned int rc_resize_allowed;
357 /*!\brief Spatial resampling up watermark.
359 * This threshold is described as a percentage of the target data buffer.
360 * When the data buffer rises above this percentage of fullness, the
361 * encoder will step up to a higher resolution version of the frame.
363 unsigned int rc_resize_up_thresh;
366 /*!\brief Spatial resampling down watermark.
368 * This threshold is described as a percentage of the target data buffer.
369 * When the data buffer falls below this percentage of fullness, the
370 * encoder will step down to a lower resolution version of the frame.
372 unsigned int rc_resize_down_thresh;
375 /*!\brief Rate control algorithm to use.
377 * Indicates whether the end usage of this stream is to be streamed over
378 * a bandwidth constrained link, indicating that Constant Bit Rate (CBR)
379 * mode should be used, or whether it will be played back on a high
380 * bandwidth link, as from a local disk, where higher variations in
381 * bitrate are acceptable.
383 enum vpx_rc_mode rc_end_usage;
386 /*!\brief Two-pass stats buffer.
388 * A buffer containing all of the stats packets produced in the first
389 * pass, concatenated.
391 struct vpx_fixed_buf rc_twopass_stats_in;
394 /*!\brief Target data rate
396 * Target bandwidth to use for this stream, in kilobits per second.
398 unsigned int rc_target_bitrate;
401 /*!\brief Max data rate for Intra frames
403 * This value controls additional clamping on the maximum size of a
404 * keyframe. It is expressed as a percentage of the average
405 * per-frame bitrate, with the special (and default) value 0 meaning
406 * unlimited, or no additional clamping beyond the codec's built-in
409 * For example, to allocate no more than 4.5 frames worth of bitrate
410 * to a keyframe, set this to 450.
413 unsigned int rc_max_intra_bitrate_pct;
421 /*!\brief Minimum (Best Quality) Quantizer
423 * The quantizer is the most direct control over the quality of the
424 * encoded image. The range of valid values for the quantizer is codec
425 * specific. Consult the documentation for the codec to determine the
426 * values to use. To determine the range programmatically, call
427 * vpx_codec_enc_config_default() with a usage value of 0.
429 unsigned int rc_min_quantizer;
432 /*!\brief Maximum (Worst Quality) Quantizer
434 * The quantizer is the most direct control over the quality of the
435 * encoded image. The range of valid values for the quantizer is codec
436 * specific. Consult the documentation for the codec to determine the
437 * values to use. To determine the range programmatically, call
438 * vpx_codec_enc_config_default() with a usage value of 0.
440 unsigned int rc_max_quantizer;
448 /*!\brief Rate control undershoot tolerance
450 * This value, expressed as a percentage of the target bitrate, describes
451 * the target bitrate for easier frames, allowing bits to be saved for
452 * harder frames. Set to zero to use the codec default.
454 unsigned int rc_undershoot_pct;
457 /*!\brief Rate control overshoot tolerance
459 * This value, expressed as a percentage of the target bitrate, describes
460 * the maximum allowed bitrate for a given frame. Set to zero to use the
463 unsigned int rc_overshoot_pct;
467 * decoder buffer model parameters
471 /*!\brief Decoder Buffer Size
473 * This value indicates the amount of data that may be buffered by the
474 * decoding application. Note that this value is expressed in units of
475 * time (milliseconds). For example, a value of 5000 indicates that the
476 * client will buffer (at least) 5000ms worth of encoded data. Use the
477 * target bitrate (#rc_target_bitrate) to convert to bits/bytes, if
480 unsigned int rc_buf_sz;
483 /*!\brief Decoder Buffer Initial Size
485 * This value indicates the amount of data that will be buffered by the
486 * decoding application prior to beginning playback. This value is
487 * expressed in units of time (milliseconds). Use the target bitrate
488 * (#rc_target_bitrate) to convert to bits/bytes, if necessary.
490 unsigned int rc_buf_initial_sz;
493 /*!\brief Decoder Buffer Optimal Size
495 * This value indicates the amount of data that the encoder should try
496 * to maintain in the decoder's buffer. This value is expressed in units
497 * of time (milliseconds). Use the target bitrate (#rc_target_bitrate)
498 * to convert to bits/bytes, if necessary.
500 unsigned int rc_buf_optimal_sz;
504 * 2 pass rate control parameters
508 /*!\brief Two-pass mode CBR/VBR bias
510 * Bias, expressed on a scale of 0 to 100, for determining target size
511 * for the current frame. The value 0 indicates the optimal CBR mode
512 * value should be used. The value 100 indicates the optimal VBR mode
513 * value should be used. Values in between indicate which way the
514 * encoder should "lean."
516 unsigned int rc_2pass_vbr_bias_pct; /**< RC mode bias between CBR and VBR(0-100: 0->CBR, 100->VBR) */
519 /*!\brief Two-pass mode per-GOP minimum bitrate
521 * This value, expressed as a percentage of the target bitrate, indicates
522 * the minimum bitrate to be used for a single GOP (aka "section")
524 unsigned int rc_2pass_vbr_minsection_pct;
527 /*!\brief Two-pass mode per-GOP maximum bitrate
529 * This value, expressed as a percentage of the target bitrate, indicates
530 * the maximum bitrate to be used for a single GOP (aka "section")
532 unsigned int rc_2pass_vbr_maxsection_pct;
536 * keyframing settings (kf)
539 /*!\brief Keyframe placement mode
541 * This value indicates whether the encoder should place keyframes at a
542 * fixed interval, or determine the optimal placement automatically
543 * (as governed by the #kf_min_dist and #kf_max_dist parameters)
545 enum vpx_kf_mode kf_mode;
548 /*!\brief Keyframe minimum interval
550 * This value, expressed as a number of frames, prevents the encoder from
551 * placing a keyframe nearer than kf_min_dist to the previous keyframe. At
552 * least kf_min_dist frames non-keyframes will be coded before the next
553 * keyframe. Set kf_min_dist equal to kf_max_dist for a fixed interval.
555 unsigned int kf_min_dist;
558 /*!\brief Keyframe maximum interval
560 * This value, expressed as a number of frames, forces the encoder to code
561 * a keyframe if one has not been coded in the last kf_max_dist frames.
562 * A value of 0 implies all frames will be keyframes. Set kf_min_dist
563 * equal to kf_max_dist for a fixed interval.
565 unsigned int kf_max_dist;
567 } vpx_codec_enc_cfg_t; /**< alias for struct vpx_codec_enc_cfg */
570 /*!\brief Initialize an encoder instance
572 * Initializes a encoder context using the given interface. Applications
573 * should call the vpx_codec_enc_init convenience macro instead of this
574 * function directly, to ensure that the ABI version number parameter
575 * is properly initialized.
577 * In XMA mode (activated by setting VPX_CODEC_USE_XMA in the flags
578 * parameter), the storage pointed to by the cfg parameter must be
579 * kept readable and stable until all memory maps have been set.
581 * \param[in] ctx Pointer to this instance's context.
582 * \param[in] iface Pointer to the algorithm interface to use.
583 * \param[in] cfg Configuration to use, if known. May be NULL.
584 * \param[in] flags Bitfield of VPX_CODEC_USE_* flags
585 * \param[in] ver ABI version number. Must be set to
586 * VPX_ENCODER_ABI_VERSION
587 * \retval #VPX_CODEC_OK
588 * The decoder algorithm initialized.
589 * \retval #VPX_CODEC_MEM_ERROR
590 * Memory allocation failed.
592 vpx_codec_err_t vpx_codec_enc_init_ver(vpx_codec_ctx_t *ctx,
593 vpx_codec_iface_t *iface,
594 vpx_codec_enc_cfg_t *cfg,
595 vpx_codec_flags_t flags,
599 /*!\brief Convenience macro for vpx_codec_enc_init_ver()
601 * Ensures the ABI version parameter is properly set.
603 #define vpx_codec_enc_init(ctx, iface, cfg, flags) \
604 vpx_codec_enc_init_ver(ctx, iface, cfg, flags, VPX_ENCODER_ABI_VERSION)
607 /*!\brief Get a default configuration
609 * Initializes a encoder configuration structure with default values. Supports
610 * the notion of "usages" so that an algorithm may offer different default
611 * settings depending on the user's intended goal. This function \ref SHOULD
612 * be called by all applications to initialize the configuration structure
613 * before specializing the configuration with application specific values.
615 * \param[in] iface Pointer to the algorithm interface to use.
616 * \param[out] cfg Configuration buffer to populate
617 * \param[in] usage End usage. Set to 0 or use codec specific values.
619 * \retval #VPX_CODEC_OK
620 * The configuration was populated.
621 * \retval #VPX_CODEC_INCAPABLE
622 * Interface is not an encoder interface.
623 * \retval #VPX_CODEC_INVALID_PARAM
624 * A parameter was NULL, or the usage value was not recognized.
626 vpx_codec_err_t vpx_codec_enc_config_default(vpx_codec_iface_t *iface,
627 vpx_codec_enc_cfg_t *cfg,
631 /*!\brief Set or change configuration
633 * Reconfigures an encoder instance according to the given configuration.
635 * \param[in] ctx Pointer to this instance's context
636 * \param[in] cfg Configuration buffer to use
638 * \retval #VPX_CODEC_OK
639 * The configuration was populated.
640 * \retval #VPX_CODEC_INCAPABLE
641 * Interface is not an encoder interface.
642 * \retval #VPX_CODEC_INVALID_PARAM
643 * A parameter was NULL, or the usage value was not recognized.
645 vpx_codec_err_t vpx_codec_enc_config_set(vpx_codec_ctx_t *ctx,
646 const vpx_codec_enc_cfg_t *cfg);
649 /*!\brief Get global stream headers
651 * Retrieves a stream level global header packet, if supported by the codec.
653 * \param[in] ctx Pointer to this instance's context
656 * Encoder does not support global header
658 * Pointer to buffer containing global header packet
660 vpx_fixed_buf_t *vpx_codec_get_global_headers(vpx_codec_ctx_t *ctx);
663 #define VPX_DL_REALTIME (1) /**< deadline parameter analogous to
664 * VPx REALTIME mode. */
665 #define VPX_DL_GOOD_QUALITY (1000000) /**< deadline parameter analogous to
666 * VPx GOOD QUALITY mode. */
667 #define VPX_DL_BEST_QUALITY (0) /**< deadline parameter analogous to
668 * VPx BEST QUALITY mode. */
669 /*!\brief Encode a frame
671 * Encodes a video frame at the given "presentation time." The presentation
672 * time stamp (PTS) \ref MUST be strictly increasing.
674 * The encoder supports the notion of a soft real-time deadline. Given a
675 * non-zero value to the deadline parameter, the encoder will make a "best
676 * effort" guarantee to return before the given time slice expires. It is
677 * implicit that limiting the available time to encode will degrade the
678 * output quality. The encoder can be given an unlimited time to produce the
679 * best possible frame by specifying a deadline of '0'. This deadline
680 * supercedes the VPx notion of "best quality, good quality, realtime".
681 * Applications that wish to map these former settings to the new deadline
682 * based system can use the symbols #VPX_DL_REALTIME, #VPX_DL_GOOD_QUALITY,
683 * and #VPX_DL_BEST_QUALITY.
685 * When the last frame has been passed to the encoder, this function should
686 * continue to be called, with the img parameter set to NULL. This will
687 * signal the end-of-stream condition to the encoder and allow it to encode
688 * any held buffers. Encoding is complete when vpx_codec_encode() is called
689 * and vpx_codec_get_cx_data() returns no data.
691 * \param[in] ctx Pointer to this instance's context
692 * \param[in] img Image data to encode, NULL to flush.
693 * \param[in] pts Presentation time stamp, in timebase units.
694 * \param[in] duration Duration to show frame, in timebase units.
695 * \param[in] flags Flags to use for encoding this frame.
696 * \param[in] deadline Time to spend encoding, in microseconds. (0=infinite)
698 * \retval #VPX_CODEC_OK
699 * The configuration was populated.
700 * \retval #VPX_CODEC_INCAPABLE
701 * Interface is not an encoder interface.
702 * \retval #VPX_CODEC_INVALID_PARAM
703 * A parameter was NULL, the image format is unsupported, etc.
705 vpx_codec_err_t vpx_codec_encode(vpx_codec_ctx_t *ctx,
706 const vpx_image_t *img,
708 unsigned long duration,
709 vpx_enc_frame_flags_t flags,
710 unsigned long deadline);
713 /*!\brief Set compressed data output buffer
715 * Sets the buffer that the codec should output the compressed data
716 * into. This call effectively sets the buffer pointer returned in the
717 * next VPX_CODEC_CX_FRAME_PKT packet. Subsequent packets will be
718 * appended into this buffer. The buffer is preserved across frames,
719 * so applications must periodically call this function after flushing
720 * the accumulated compressed data to disk or to the network to reset
721 * the pointer to the buffer's head.
723 * `pad_before` bytes will be skipped before writing the compressed
724 * data, and `pad_after` bytes will be appended to the packet. The size
725 * of the packet will be the sum of the size of the actual compressed
726 * data, pad_before, and pad_after. The padding bytes will be preserved
729 * Note that calling this function does not guarantee that the returned
730 * compressed data will be placed into the specified buffer. In the
731 * event that the encoded data will not fit into the buffer provided,
732 * the returned packet \ref MAY point to an internal buffer, as it would
733 * if this call were never used. In this event, the output packet will
734 * NOT have any padding, and the application must free space and copy it
735 * to the proper place. This is of particular note in configurations
736 * that may output multiple packets for a single encoded frame (e.g., lagged
737 * encoding) or if the application does not reset the buffer periodically.
739 * Applications may restore the default behavior of the codec providing
740 * the compressed data buffer by calling this function with a NULL
743 * Applications \ref MUSTNOT call this function during iteration of
744 * vpx_codec_get_cx_data().
746 * \param[in] ctx Pointer to this instance's context
747 * \param[in] buf Buffer to store compressed data into
748 * \param[in] pad_before Bytes to skip before writing compressed data
749 * \param[in] pad_after Bytes to skip after writing compressed data
751 * \retval #VPX_CODEC_OK
752 * The buffer was set successfully.
753 * \retval #VPX_CODEC_INVALID_PARAM
754 * A parameter was NULL, the image format is unsupported, etc.
756 vpx_codec_err_t vpx_codec_set_cx_data_buf(vpx_codec_ctx_t *ctx,
757 const vpx_fixed_buf_t *buf,
758 unsigned int pad_before,
759 unsigned int pad_after);
762 /*!\brief Encoded data iterator
764 * Iterates over a list of data packets to be passed from the encoder to the
765 * application. The different kinds of packets available are enumerated in
766 * #vpx_codec_cx_pkt_kind.
768 * #VPX_CODEC_CX_FRAME_PKT packets should be passed to the application's
769 * muxer. Multiple compressed frames may be in the list.
770 * #VPX_CODEC_STATS_PKT packets should be appended to a global buffer.
772 * The application \ref MUST silently ignore any packet kinds that it does
773 * not recognize or support.
775 * The data buffers returned from this function are only guaranteed to be
776 * valid until the application makes another call to any vpx_codec_* function.
778 * \param[in] ctx Pointer to this instance's context
779 * \param[in,out] iter Iterator storage, initialized to NULL
781 * \return Returns a pointer to an output data packet (compressed frame data,
782 * two-pass statistics, etc.) or NULL to signal end-of-list.
785 const vpx_codec_cx_pkt_t *vpx_codec_get_cx_data(vpx_codec_ctx_t *ctx,
786 vpx_codec_iter_t *iter);
789 /*!\brief Get Preview Frame
791 * Returns an image that can be used as a preview. Shows the image as it would
792 * exist at the decompressor. The application \ref MUST NOT write into this
795 * \param[in] ctx Pointer to this instance's context
797 * \return Returns a pointer to a preview image, or NULL if no image is
801 const vpx_image_t *vpx_codec_get_preview_frame(vpx_codec_ctx_t *ctx);
804 /*!@} - end defgroup encoder*/