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1 /*
2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
3  *
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.
9  */
10 
11 
12 /*!\defgroup encoder Encoder Algorithm Interface
13  * \ingroup codec
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.
17  * @{
18  */
19 
20 /*!\file vpx_encoder.h
21  * \brief Describes the encoder algorithm interface to applications.
22  *
23  * This file describes the interface between an application and a
24  * video encoder algorithm.
25  *
26  */
27 #ifdef __cplusplus
28 extern "C" {
29 #endif
30 
31 #ifndef VPX_ENCODER_H
32 #define VPX_ENCODER_H
33 #include "vpx_codec.h"
34 
35 
36     /*!\brief Current ABI version number
37      *
38      * \internal
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
43      */
44 #define VPX_ENCODER_ABI_VERSION (2 + VPX_CODEC_ABI_VERSION) /**<\hideinitializer*/
45 
46 
47     /*! \brief Encoder capabilities bitfield
48      *
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
52      *  by an encoder.
53      *
54      *  The available flags are specifiedby VPX_CODEC_CAP_* defines.
55      */
56 #define VPX_CODEC_CAP_PSNR  0x10000 /**< Can issue PSNR packets */
57 
58 
59     /*! \brief Initialization-time Feature Enabling
60      *
61      *  Certain codec features must be known at initialization time, to allow
62      *  for proper memory allocation.
63      *
64      *  The available flags are specified by VPX_CODEC_USE_* defines.
65      */
66 #define VPX_CODEC_USE_PSNR  0x10000 /**< Calculate PSNR on each frame */
67 
68 
69     /*!\brief Generic fixed size buffer structure
70      *
71      * This structure is able to hold a reference to any fixed size buffer.
72      */
73     typedef struct vpx_fixed_buf
74     {
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 */
78 
79 
80     /*!\brief Time Stamp Type
81      *
82      * An integer, which when multiplied by the stream's time base, provides
83      * the absolute time of a sample.
84      */
85     typedef int64_t vpx_codec_pts_t;
86 
87 
88     /*!\brief Compressed Frame Flags
89      *
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)
94      */
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
99                 this one) */
100 #define VPX_FRAME_IS_INVISIBLE 0x4 /**< frame should be decoded but will not
101     be shown */
102 
103 
104     /*!\brief Encoder output packet variants
105      *
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.
109      */
110     enum vpx_codec_cx_pkt_kind
111     {
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  */
116     };
117 
118 
119     /*!\brief Encoder output packet
120      *
121      * This structure contains the different kinds of output data the encoder
122      * may produce while compressing a frame.
123      */
124     typedef struct vpx_codec_cx_pkt
125     {
126         enum vpx_codec_cx_pkt_kind  kind; /**< packet variant */
127         union
128         {
129             struct
130             {
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 */
140             struct vpx_psnr_pkt
141             {
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 */
147 
148             /* This packet size is fixed to allow codecs to extend this
149              * interface without having to manage storage for raw packets,
150              * ie if it's smaller than 128 bytes, you can store in the
151              * packet list directly.
152              */
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 */
156 
157 
158     /*!\brief Rational Number
159      *
160      * This structure holds a fractional value.
161      */
162     typedef struct vpx_rational
163     {
164         int num; /**< fraction numerator */
165         int den; /**< fraction denominator */
166     } vpx_rational_t; /**< alias for struct vpx_rational */
167 
168 
169     /*!\brief Multi-pass Encoding Pass */
170     enum vpx_enc_pass
171     {
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 */
175     };
176 
177 
178     /*!\brief Rate control mode */
179     enum vpx_rc_mode
180     {
181         VPX_VBR, /**< Variable Bit Rate (VBR) mode */
182         VPX_CBR  /**< Constant Bit Rate (CBR) mode */
183     };
184 
185 
186     /*!\brief Keyframe placement mode.
187      *
188      * This enumeration determines whether keyframes are placed automatically by
189      * the encoder or whether this behavior is disabled. Older releases of this
190      * SDK were implemented such that VPX_KF_FIXED meant keyframes were disabled.
191      * This name is confusing for this behavior, so the new symbols to be used
192      * are VPX_KF_AUTO and VPX_KF_DISABLED.
193      */
194     enum vpx_kf_mode
195     {
196         VPX_KF_FIXED, /**< deprecated, implies VPX_KF_DISABLED */
197         VPX_KF_AUTO,  /**< Encoder determines optimal placement automatically */
198         VPX_KF_DISABLED = 0 /**< Encoder does not place keyframes. */
199     };
200 
201 
202     /*!\brief Encoded Frame Flags
203      *
204      * This type indicates a bitfield to be passed to vpx_codec_encode(), defining
205      * per-frame boolean values. By convention, bits common to all codecs will be
206      * named VPX_EFLAG_*, and bits specific to an algorithm will be named
207      * /algo/_eflag_*. The lower order 16 bits are reserved for common use.
208      */
209     typedef long vpx_enc_frame_flags_t;
210 #define VPX_EFLAG_FORCE_KF (1<<0)  /**< Force this frame to be a keyframe */
211 
212 
213     /*!\brief Encoder configuration structure
214      *
215      * This structure contains the encoder settings that have common representations
216      * across all codecs. This doesn't imply that all codecs support all features,
217      * however.
218      */
219     typedef struct vpx_codec_enc_cfg
220     {
221         /*
222          * generic settings (g)
223          */
224 
225         /*!\brief Algorithm specific "usage" value
226          *
227          * Algorithms may define multiple values for usage, which may convey the
228          * intent of how the application intends to use the stream. If this value
229          * is non-zero, consult the documentation for the codec to determine its
230          * meaning.
231          */
232         unsigned int           g_usage;
233 
234 
235         /*!\brief Maximum number of threads to use
236          *
237          * For multi-threaded implementations, use no more than this number of
238          * threads. The codec may use fewer threads than allowed. The value
239          * 0 is equivalent to the value 1.
240          */
241         unsigned int           g_threads;
242 
243 
244         /*!\brief Bitstream profile to use
245          *
246          * Some codecs support a notion of multiple bitstream profiles. Typically
247          * this maps to a set of features that are turned on or off. Often the
248          * profile to use is determined by the features of the intended decoder.
249          * Consult the documentation for the codec to determine the valid values
250          * for this parameter, or set to zero for a sane default.
251          */
252         unsigned int           g_profile;  /**< profile of bitstream to use */
253 
254 
255 
256         /*!\brief Width of the frame
257          *
258          * This value identifies the presentation resolution of the frame,
259          * in pixels. Note that the frames passed as input to the encoder must
260          * have this resolution. Frames will be presented by the decoder in this
261          * resolution, independent of any spatial resampling the encoder may do.
262          */
263         unsigned int           g_w;
264 
265 
266         /*!\brief Height of the frame
267          *
268          * This value identifies the presentation resolution of the frame,
269          * in pixels. Note that the frames passed as input to the encoder must
270          * have this resolution. Frames will be presented by the decoder in this
271          * resolution, independent of any spatial resampling the encoder may do.
272          */
273         unsigned int           g_h;
274 
275 
276         /*!\brief Stream timebase units
277          *
278          * Indicates the smallest interval of time, in seconds, used by the stream.
279          * For fixed frame rate material, or variable frame rate material where
280          * frames are timed at a multiple of a given clock (ex: video capture),
281          * the \ref RECOMMENDED method is to set the timebase to the reciprocal
282          * of the frame rate (ex: 1001/30000 for 29.970 Hz NTSC). This allows the
283          * pts to correspond to the frame number, which can be handy. For
284          * re-encoding video from containers with absolute time timestamps, the
285          * \ref RECOMMENDED method is to set the timebase to that of the parent
286          * container or multimedia framework (ex: 1/1000 for ms, as in FLV).
287          */
288         struct vpx_rational    g_timebase;
289 
290 
291         /*!\brief Enable error resilient mode.
292          *
293          * Error resilient mode indicates to the encoder that it should take
294          * measures appropriate for streaming over lossy or noisy links, if
295          * possible. Set to 1 to enable this feature, 0 to disable it.
296          */
297         unsigned int           g_error_resilient;
298 
299 
300         /*!\brief Multi-pass Encoding Mode
301          *
302          * This value should be set to the current phase for multi-pass encoding.
303          * For single pass, set to #VPX_RC_ONE_PASS.
304          */
305         enum vpx_enc_pass      g_pass;
306 
307 
308         /*!\brief Allow lagged encoding
309          *
310          * If set, this value allows the encoder to consume a number of input
311          * frames before producing output frames. This allows the encoder to
312          * base decisions for the current frame on future frames. This does
313          * increase the latency of the encoding pipeline, so it is not appropriate
314          * in all situations (ex: realtime encoding).
315          *
316          * Note that this is a maximum value -- the encoder may produce frames
317          * sooner than the given limit. Set this value to 0 to disable this
318          * feature.
319          */
320         unsigned int           g_lag_in_frames;
321 
322 
323         /*
324          * rate control settings (rc)
325          */
326 
327         /*!\brief Temporal resampling configuration, if supported by the codec.
328          *
329          * Temporal resampling allows the codec to "drop" frames as a strategy to
330          * meet its target data rate. This can cause temporal discontinuities in
331          * the encoded video, which may appear as stuttering during playback. This
332          * trade-off is often acceptable, but for many applications is not. It can
333          * be disabled in these cases.
334          *
335          * Note that not all codecs support this feature. All vpx VPx codecs do.
336          * For other codecs, consult the documentation for that algorithm.
337          *
338          * This threshold is described as a percentage of the target data buffer.
339          * When the data buffer falls below this percentage of fullness, a
340          * dropped frame is indicated. Set the threshold to zero (0) to disable
341          * this feature.
342          */
343         unsigned int           rc_dropframe_thresh;
344 
345 
346         /*!\brief Enable/disable spatial resampling, if supported by the codec.
347          *
348          * Spatial resampling allows the codec to compress a lower resolution
349          * version of the frame, which is then upscaled by the encoder to the
350          * correct presentation resolution. This increases visual quality at
351          * low data rates, at the expense of CPU time on the encoder/decoder.
352          */
353         unsigned int           rc_resize_allowed;
354 
355 
356         /*!\brief Spatial resampling up watermark.
357          *
358          * This threshold is described as a percentage of the target data buffer.
359          * When the data buffer rises above this percentage of fullness, the
360          * encoder will step up to a higher resolution version of the frame.
361          */
362         unsigned int           rc_resize_up_thresh;
363 
364 
365         /*!\brief Spatial resampling down watermark.
366          *
367          * This threshold is described as a percentage of the target data buffer.
368          * When the data buffer falls below this percentage of fullness, the
369          * encoder will step down to a lower resolution version of the frame.
370          */
371         unsigned int           rc_resize_down_thresh;
372 
373 
374         /*!\brief Rate control algorithm to use.
375          *
376          * Indicates whether the end usage of this stream is to be streamed over
377          * a bandwidth constrained link, indicating that Constant Bit Rate (CBR)
378          * mode should be used, or whether it will be played back on a high
379          * bandwidth link, as from a local disk, where higher variations in
380          * bitrate are acceptable.
381          */
382         enum vpx_rc_mode       rc_end_usage;
383 
384 
385         /*!\brief Two-pass stats buffer.
386          *
387          * A buffer containing all of the stats packets produced in the first
388          * pass, concatenated.
389          */
390         struct vpx_fixed_buf   rc_twopass_stats_in;
391 
392 
393         /*!\brief Target data rate
394          *
395          * Target bandwidth to use for this stream, in kilobits per second.
396          */
397         unsigned int           rc_target_bitrate;
398 
399 
400         /*
401          * quantizer settings
402          */
403 
404 
405         /*!\brief Minimum (Best Quality) Quantizer
406          *
407          * The quantizer is the most direct control over the quality of the
408          * encoded image. The range of valid values for the quantizer is codec
409          * specific. Consult the documentation for the codec to determine the
410          * values to use. To determine the range programmatically, call
411          * vpx_codec_enc_config_default() with a usage value of 0.
412          */
413         unsigned int           rc_min_quantizer;
414 
415 
416         /*!\brief Maximum (Worst Quality) Quantizer
417          *
418          * The quantizer is the most direct control over the quality of the
419          * encoded image. The range of valid values for the quantizer is codec
420          * specific. Consult the documentation for the codec to determine the
421          * values to use. To determine the range programmatically, call
422          * vpx_codec_enc_config_default() with a usage value of 0.
423          */
424         unsigned int           rc_max_quantizer;
425 
426 
427         /*
428          * bitrate tolerance
429          */
430 
431 
432         /*!\brief Rate control undershoot tolerance
433          *
434          * This value, expressed as a percentage of the target bitrate, describes
435          * the target bitrate for easier frames, allowing bits to be saved for
436          * harder frames. Set to zero to use the codec default.
437          */
438         unsigned int           rc_undershoot_pct;
439 
440 
441         /*!\brief Rate control overshoot tolerance
442          *
443          * This value, expressed as a percentage of the target bitrate, describes
444          * the maximum allowed bitrate for a given frame.  Set to zero to use the
445          * codec default.
446          */
447         unsigned int           rc_overshoot_pct;
448 
449 
450         /*
451          * decoder buffer model parameters
452          */
453 
454 
455         /*!\brief Decoder Buffer Size
456          *
457          * This value indicates the amount of data that may be buffered by the
458          * decoding application. Note that this value is expressed in units of
459          * time (milliseconds). For example, a value of 5000 indicates that the
460          * client will buffer (at least) 5000ms worth of encoded data. Use the
461          * target bitrate (#rc_target_bitrate) to convert to bits/bytes, if
462          * necessary.
463          */
464         unsigned int           rc_buf_sz;
465 
466 
467         /*!\brief Decoder Buffer Initial Size
468          *
469          * This value indicates the amount of data that will be buffered by the
470          * decoding application prior to beginning playback. This value is
471          * expressed in units of time (milliseconds). Use the target bitrate
472          * (#rc_target_bitrate) to convert to bits/bytes, if necessary.
473          */
474         unsigned int           rc_buf_initial_sz;
475 
476 
477         /*!\brief Decoder Buffer Optimal Size
478          *
479          * This value indicates the amount of data that the encoder should try
480          * to maintain in the decoder's buffer. This value is expressed in units
481          * of time (milliseconds). Use the target bitrate (#rc_target_bitrate)
482          * to convert to bits/bytes, if necessary.
483          */
484         unsigned int           rc_buf_optimal_sz;
485 
486 
487         /*
488          * 2 pass rate control parameters
489          */
490 
491 
492         /*!\brief Two-pass mode CBR/VBR bias
493          *
494          * Bias, expressed on a scale of 0 to 100, for determining target size
495          * for the current frame. The value 0 indicates the optimal CBR mode
496          * value should be used. The value 100 indicates the optimal VBR mode
497          * value should be used. Values in between indicate which way the
498          * encoder should "lean."
499          */
500         unsigned int           rc_2pass_vbr_bias_pct;       /**< RC mode bias between CBR and VBR(0-100: 0->CBR, 100->VBR)   */
501 
502 
503         /*!\brief Two-pass mode per-GOP minimum bitrate
504          *
505          * This value, expressed as a percentage of the target bitrate, indicates
506          * the minimum bitrate to be used for a single GOP (aka "section")
507          */
508         unsigned int           rc_2pass_vbr_minsection_pct;
509 
510 
511         /*!\brief Two-pass mode per-GOP maximum bitrate
512          *
513          * This value, expressed as a percentage of the target bitrate, indicates
514          * the maximum bitrate to be used for a single GOP (aka "section")
515          */
516         unsigned int           rc_2pass_vbr_maxsection_pct;
517 
518 
519         /*
520          * keyframing settings (kf)
521          */
522 
523         /*!\brief Keyframe placement mode
524          *
525          * This value indicates whether the encoder should place keyframes at a
526          * fixed interval, or determine the optimal placement automatically
527          * (as governed by the #kf_min_dist and #kf_max_dist parameters)
528          */
529         enum vpx_kf_mode       kf_mode;
530 
531 
532         /*!\brief Keyframe minimum interval
533          *
534          * This value, expressed as a number of frames, prevents the encoder from
535          * placing a keyframe nearer than kf_min_dist to the previous keyframe. At
536          * least kf_min_dist frames non-keyframes will be coded before the next
537          * keyframe. Set kf_min_dist equal to kf_max_dist for a fixed interval.
538          */
539         unsigned int           kf_min_dist;
540 
541 
542         /*!\brief Keyframe maximum interval
543          *
544          * This value, expressed as a number of frames, forces the encoder to code
545          * a keyframe if one has not been coded in the last kf_max_dist frames.
546          * A value of 0 implies all frames will be keyframes. Set kf_min_dist
547          * equal to kf_max_dist for a fixed interval.
548          */
549         unsigned int           kf_max_dist;
550 
551     } vpx_codec_enc_cfg_t; /**< alias for struct vpx_codec_enc_cfg */
552 
553 
554     /*!\brief Initialize an encoder instance
555      *
556      * Initializes a encoder context using the given interface. Applications
557      * should call the vpx_codec_enc_init convenience macro instead of this
558      * function directly, to ensure that the ABI version number parameter
559      * is properly initialized.
560      *
561      * In XMA mode (activated by setting VPX_CODEC_USE_XMA in the flags
562      * parameter), the storage pointed to by the cfg parameter must be
563      * kept readable and stable until all memory maps have been set.
564      *
565      * \param[in]    ctx     Pointer to this instance's context.
566      * \param[in]    iface   Pointer to the algorithm interface to use.
567      * \param[in]    cfg     Configuration to use, if known. May be NULL.
568      * \param[in]    flags   Bitfield of VPX_CODEC_USE_* flags
569      * \param[in]    ver     ABI version number. Must be set to
570      *                       VPX_ENCODER_ABI_VERSION
571      * \retval #VPX_CODEC_OK
572      *     The decoder algorithm initialized.
573      * \retval #VPX_CODEC_MEM_ERROR
574      *     Memory allocation failed.
575      */
576     vpx_codec_err_t vpx_codec_enc_init_ver(vpx_codec_ctx_t      *ctx,
577                                            vpx_codec_iface_t    *iface,
578                                            vpx_codec_enc_cfg_t  *cfg,
579                                            vpx_codec_flags_t     flags,
580                                            int                   ver);
581 
582 
583     /*!\brief Convenience macro for vpx_codec_enc_init_ver()
584      *
585      * Ensures the ABI version parameter is properly set.
586      */
587 #define vpx_codec_enc_init(ctx, iface, cfg, flags) \
588     vpx_codec_enc_init_ver(ctx, iface, cfg, flags, VPX_ENCODER_ABI_VERSION)
589 
590 
591     /*!\brief Get a default configuration
592      *
593      * Initializes a encoder configuration structure with default values. Supports
594      * the notion of "usages" so that an algorithm may offer different default
595      * settings depending on the user's intended goal. This function \ref SHOULD
596      * be called by all applications to initialize the configuration structure
597      * before specializing the configuration with application specific values.
598      *
599      * \param[in]    iface   Pointer to the algorithm interface to use.
600      * \param[out]   cfg     Configuration buffer to populate
601      * \param[in]    usage   End usage. Set to 0 or use codec specific values.
602      *
603      * \retval #VPX_CODEC_OK
604      *     The configuration was populated.
605      * \retval #VPX_CODEC_INCAPABLE
606      *     Interface is not an encoder interface.
607      * \retval #VPX_CODEC_INVALID_PARAM
608      *     A parameter was NULL, or the usage value was not recognized.
609      */
610     vpx_codec_err_t  vpx_codec_enc_config_default(vpx_codec_iface_t    *iface,
611             vpx_codec_enc_cfg_t  *cfg,
612             unsigned int          usage);
613 
614 
615     /*!\brief Set or change configuration
616      *
617      * Reconfigures an encoder instance according to the given configuration.
618      *
619      * \param[in]    ctx     Pointer to this instance's context
620      * \param[in]    cfg     Configuration buffer to use
621      *
622      * \retval #VPX_CODEC_OK
623      *     The configuration was populated.
624      * \retval #VPX_CODEC_INCAPABLE
625      *     Interface is not an encoder interface.
626      * \retval #VPX_CODEC_INVALID_PARAM
627      *     A parameter was NULL, or the usage value was not recognized.
628      */
629     vpx_codec_err_t  vpx_codec_enc_config_set(vpx_codec_ctx_t            *ctx,
630             const vpx_codec_enc_cfg_t  *cfg);
631 
632 
633     /*!\brief Get global stream headers
634      *
635      * Retrieves a stream level global header packet, if supported by the codec.
636      *
637      * \param[in]    ctx     Pointer to this instance's context
638      *
639      * \retval NULL
640      *     Encoder does not support global header
641      * \retval Non-NULL
642      *     Pointer to buffer containing global header packet
643      */
644     vpx_fixed_buf_t *vpx_codec_get_global_headers(vpx_codec_ctx_t   *ctx);
645 
646 
647 #define VPX_DL_REALTIME     (1)        /**< deadline parameter analogous to
648     *   VPx REALTIME mode. */
649 #define VPX_DL_GOOD_QUALITY (1000000)  /**< deadline parameter analogous to
650     *   VPx GOOD QUALITY mode. */
651 #define VPX_DL_BEST_QUALITY (0)        /**< deadline parameter analogous to
652     *   VPx BEST QUALITY mode. */
653     /*!\brief Encode a frame
654      *
655      * Encodes a video frame at the given "presentation time." The presentation
656      * time stamp (PTS) \ref MUST be strictly increasing.
657      *
658      * The encoder supports the notion of a soft real-time deadline. Given a
659      * non-zero value to the deadline parameter, the encoder will make a "best
660      * effort" guarantee to  return before the given time slice expires. It is
661      * implicit that limiting the available time to encode will degrade the
662      * output quality. The encoder can be given an unlimited time to produce the
663      * best possible frame by specifying a deadline of '0'. This deadline
664      * supercedes the VPx notion of "best quality, good quality, realtime".
665      * Applications that wish to map these former settings to the new deadline
666      * based system can use the symbols #VPX_DL_REALTIME, #VPX_DL_GOOD_QUALITY,
667      * and #VPX_DL_BEST_QUALITY.
668      *
669      * When the last frame has been passed to the encoder, this function should
670      * continue to be called, with the img parameter set to NULL. This will
671      * signal the end-of-stream condition to the encoder and allow it to encode
672      * any held buffers. Encoding is complete when vpx_codec_encode() is called
673      * and vpx_codec_get_cx_data() returns no data.
674      *
675      * \param[in]    ctx       Pointer to this instance's context
676      * \param[in]    img       Image data to encode, NULL to flush.
677      * \param[in]    pts       Presentation time stamp, in timebase units.
678      * \param[in]    duration  Duration to show frame, in timebase units.
679      * \param[in]    flags     Flags to use for encoding this frame.
680      * \param[in]    deadline  Time to spend encoding, in microseconds. (0=infinite)
681      *
682      * \retval #VPX_CODEC_OK
683      *     The configuration was populated.
684      * \retval #VPX_CODEC_INCAPABLE
685      *     Interface is not an encoder interface.
686      * \retval #VPX_CODEC_INVALID_PARAM
687      *     A parameter was NULL, the image format is unsupported, etc.
688      */
689     vpx_codec_err_t  vpx_codec_encode(vpx_codec_ctx_t            *ctx,
690                                       const vpx_image_t          *img,
691                                       vpx_codec_pts_t             pts,
692                                       unsigned long               duration,
693                                       vpx_enc_frame_flags_t       flags,
694                                       unsigned long               deadline);
695 
696 
697     /*!\brief Set compressed data output buffer
698      *
699      * Sets the buffer that the codec should output the compressed data
700      * into. This call effectively sets the buffer pointer returned in the
701      * next VPX_CODEC_CX_FRAME_PKT packet. Subsequent packets will be
702      * appended into this buffer. The buffer is preserved across frames,
703      * so applications must periodically call this function after flushing
704      * the accumulated compressed data to disk or to the network to reset
705      * the pointer to the buffer's head.
706      *
707      * `pad_before` bytes will be skipped before writing the compressed
708      * data, and `pad_after` bytes will be appended to the packet. The size
709      * of the packet will be the sum of the size of the actual compressed
710      * data, pad_before, and pad_after. The padding bytes will be preserved
711      * (not overwritten).
712      *
713      * Note that calling this function does not guarantee that the returned
714      * compressed data will be placed into the specified buffer. In the
715      * event that the encoded data will not fit into the buffer provided,
716      * the returned packet \ref MAY point to an internal buffer, as it would
717      * if this call were never used. In this event, the output packet will
718      * NOT have any padding, and the application must free space and copy it
719      * to the proper place. This is of particular note in configurations
720      * that may output multiple packets for a single encoded frame (e.g., lagged
721      * encoding) or if the application does not reset the buffer periodically.
722      *
723      * Applications may restore the default behavior of the codec providing
724      * the compressed data buffer by calling this function with a NULL
725      * buffer.
726      *
727      * Applications \ref MUSTNOT call this function during iteration of
728      * vpx_codec_get_cx_data().
729      *
730      * \param[in]    ctx         Pointer to this instance's context
731      * \param[in]    buf         Buffer to store compressed data into
732      * \param[in]    pad_before  Bytes to skip before writing compressed data
733      * \param[in]    pad_after   Bytes to skip after writing compressed data
734      *
735      * \retval #VPX_CODEC_OK
736      *     The buffer was set successfully.
737      * \retval #VPX_CODEC_INVALID_PARAM
738      *     A parameter was NULL, the image format is unsupported, etc.
739      */
740     vpx_codec_err_t vpx_codec_set_cx_data_buf(vpx_codec_ctx_t       *ctx,
741             const vpx_fixed_buf_t *buf,
742             unsigned int           pad_before,
743             unsigned int           pad_after);
744 
745 
746     /*!\brief Encoded data iterator
747      *
748      * Iterates over a list of data packets to be passed from the encoder to the
749      * application. The different kinds of packets available are enumerated in
750      * #vpx_codec_cx_pkt_kind.
751      *
752      * #VPX_CODEC_CX_FRAME_PKT packets should be passed to the application's
753      * muxer. Multiple compressed frames may be in the list.
754      * #VPX_CODEC_STATS_PKT packets should be appended to a global buffer.
755      *
756      * The application \ref MUST silently ignore any packet kinds that it does
757      * not recognize or support.
758      *
759      * The data buffers returned from this function are only guaranteed to be
760      * valid until the application makes another call to any vpx_codec_* function.
761      *
762      * \param[in]     ctx      Pointer to this instance's context
763      * \param[in,out] iter     Iterator storage, initialized to NULL
764      *
765      * \return Returns a pointer to an output data packet (compressed frame data,
766      *         two-pass statistics, etc.) or NULL to signal end-of-list.
767      *
768      */
769     const vpx_codec_cx_pkt_t *vpx_codec_get_cx_data(vpx_codec_ctx_t   *ctx,
770             vpx_codec_iter_t  *iter);
771 
772 
773     /*!\brief Get Preview Frame
774      *
775      * Returns an image that can be used as a preview. Shows the image as it would
776      * exist at the decompressor. The application \ref MUST NOT write into this
777      * image buffer.
778      *
779      * \param[in]     ctx      Pointer to this instance's context
780      *
781      * \return Returns a pointer to a preview image, or NULL if no image is
782      *         available.
783      *
784      */
785     const vpx_image_t *vpx_codec_get_preview_frame(vpx_codec_ctx_t   *ctx);
786 
787 
788     /*!@} - end defgroup encoder*/
789 
790 #endif
791 #ifdef __cplusplus
792 }
793 #endif
794