• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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
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 specified by 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              * i.e., 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         VPX_CQ   /**< Constant Quality  (CQ)  mode */
184     };
185 
186 
187     /*!\brief Keyframe placement mode.
188      *
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.
194      */
195     enum vpx_kf_mode
196     {
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. */
200     };
201 
202 
203     /*!\brief Encoded Frame Flags
204      *
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.
209      */
210     typedef long vpx_enc_frame_flags_t;
211 #define VPX_EFLAG_FORCE_KF (1<<0)  /**< Force this frame to be a keyframe */
212 
213 
214     /*!\brief Encoder configuration structure
215      *
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,
218      * however.
219      */
220     typedef struct vpx_codec_enc_cfg
221     {
222         /*
223          * generic settings (g)
224          */
225 
226         /*!\brief Algorithm specific "usage" value
227          *
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
231          * meaning.
232          */
233         unsigned int           g_usage;
234 
235 
236         /*!\brief Maximum number of threads to use
237          *
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.
241          */
242         unsigned int           g_threads;
243 
244 
245         /*!\brief Bitstream profile to use
246          *
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.
252          */
253         unsigned int           g_profile;  /**< profile of bitstream to use */
254 
255 
256 
257         /*!\brief Width of the frame
258          *
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.
263          */
264         unsigned int           g_w;
265 
266 
267         /*!\brief Height of the frame
268          *
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.
273          */
274         unsigned int           g_h;
275 
276 
277         /*!\brief Stream timebase units
278          *
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).
288          */
289         struct vpx_rational    g_timebase;
290 
291 
292         /*!\brief Enable error resilient mode.
293          *
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.
297          */
298         unsigned int           g_error_resilient;
299 
300 
301         /*!\brief Multi-pass Encoding Mode
302          *
303          * This value should be set to the current phase for multi-pass encoding.
304          * For single pass, set to #VPX_RC_ONE_PASS.
305          */
306         enum vpx_enc_pass      g_pass;
307 
308 
309         /*!\brief Allow lagged encoding
310          *
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).
316          *
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
319          * feature.
320          */
321         unsigned int           g_lag_in_frames;
322 
323 
324         /*
325          * rate control settings (rc)
326          */
327 
328         /*!\brief Temporal resampling configuration, if supported by the codec.
329          *
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.
335          *
336          * Note that not all codecs support this feature. All vpx VPx codecs do.
337          * For other codecs, consult the documentation for that algorithm.
338          *
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
342          * this feature.
343          */
344         unsigned int           rc_dropframe_thresh;
345 
346 
347         /*!\brief Enable/disable spatial resampling, if supported by the codec.
348          *
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.
353          */
354         unsigned int           rc_resize_allowed;
355 
356 
357         /*!\brief Spatial resampling up watermark.
358          *
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.
362          */
363         unsigned int           rc_resize_up_thresh;
364 
365 
366         /*!\brief Spatial resampling down watermark.
367          *
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.
371          */
372         unsigned int           rc_resize_down_thresh;
373 
374 
375         /*!\brief Rate control algorithm to use.
376          *
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.
382          */
383         enum vpx_rc_mode       rc_end_usage;
384 
385 
386         /*!\brief Two-pass stats buffer.
387          *
388          * A buffer containing all of the stats packets produced in the first
389          * pass, concatenated.
390          */
391         struct vpx_fixed_buf   rc_twopass_stats_in;
392 
393 
394         /*!\brief Target data rate
395          *
396          * Target bandwidth to use for this stream, in kilobits per second.
397          */
398         unsigned int           rc_target_bitrate;
399 
400 
401         /*
402          * quantizer settings
403          */
404 
405 
406         /*!\brief Minimum (Best Quality) Quantizer
407          *
408          * The quantizer is the most direct control over the quality of the
409          * encoded image. The range of valid values for the quantizer is codec
410          * specific. Consult the documentation for the codec to determine the
411          * values to use. To determine the range programmatically, call
412          * vpx_codec_enc_config_default() with a usage value of 0.
413          */
414         unsigned int           rc_min_quantizer;
415 
416 
417         /*!\brief Maximum (Worst Quality) Quantizer
418          *
419          * The quantizer is the most direct control over the quality of the
420          * encoded image. The range of valid values for the quantizer is codec
421          * specific. Consult the documentation for the codec to determine the
422          * values to use. To determine the range programmatically, call
423          * vpx_codec_enc_config_default() with a usage value of 0.
424          */
425         unsigned int           rc_max_quantizer;
426 
427 
428         /*
429          * bitrate tolerance
430          */
431 
432 
433         /*!\brief Rate control undershoot tolerance
434          *
435          * This value, expressed as a percentage of the target bitrate, describes
436          * the target bitrate for easier frames, allowing bits to be saved for
437          * harder frames. Set to zero to use the codec default.
438          */
439         unsigned int           rc_undershoot_pct;
440 
441 
442         /*!\brief Rate control overshoot tolerance
443          *
444          * This value, expressed as a percentage of the target bitrate, describes
445          * the maximum allowed bitrate for a given frame.  Set to zero to use the
446          * codec default.
447          */
448         unsigned int           rc_overshoot_pct;
449 
450 
451         /*
452          * decoder buffer model parameters
453          */
454 
455 
456         /*!\brief Decoder Buffer Size
457          *
458          * This value indicates the amount of data that may be buffered by the
459          * decoding application. Note that this value is expressed in units of
460          * time (milliseconds). For example, a value of 5000 indicates that the
461          * client will buffer (at least) 5000ms worth of encoded data. Use the
462          * target bitrate (#rc_target_bitrate) to convert to bits/bytes, if
463          * necessary.
464          */
465         unsigned int           rc_buf_sz;
466 
467 
468         /*!\brief Decoder Buffer Initial Size
469          *
470          * This value indicates the amount of data that will be buffered by the
471          * decoding application prior to beginning playback. This value is
472          * expressed in units of time (milliseconds). Use the target bitrate
473          * (#rc_target_bitrate) to convert to bits/bytes, if necessary.
474          */
475         unsigned int           rc_buf_initial_sz;
476 
477 
478         /*!\brief Decoder Buffer Optimal Size
479          *
480          * This value indicates the amount of data that the encoder should try
481          * to maintain in the decoder's buffer. This value is expressed in units
482          * of time (milliseconds). Use the target bitrate (#rc_target_bitrate)
483          * to convert to bits/bytes, if necessary.
484          */
485         unsigned int           rc_buf_optimal_sz;
486 
487 
488         /*
489          * 2 pass rate control parameters
490          */
491 
492 
493         /*!\brief Two-pass mode CBR/VBR bias
494          *
495          * Bias, expressed on a scale of 0 to 100, for determining target size
496          * for the current frame. The value 0 indicates the optimal CBR mode
497          * value should be used. The value 100 indicates the optimal VBR mode
498          * value should be used. Values in between indicate which way the
499          * encoder should "lean."
500          */
501         unsigned int           rc_2pass_vbr_bias_pct;       /**< RC mode bias between CBR and VBR(0-100: 0->CBR, 100->VBR)   */
502 
503 
504         /*!\brief Two-pass mode per-GOP minimum bitrate
505          *
506          * This value, expressed as a percentage of the target bitrate, indicates
507          * the minimum bitrate to be used for a single GOP (aka "section")
508          */
509         unsigned int           rc_2pass_vbr_minsection_pct;
510 
511 
512         /*!\brief Two-pass mode per-GOP maximum bitrate
513          *
514          * This value, expressed as a percentage of the target bitrate, indicates
515          * the maximum bitrate to be used for a single GOP (aka "section")
516          */
517         unsigned int           rc_2pass_vbr_maxsection_pct;
518 
519 
520         /*
521          * keyframing settings (kf)
522          */
523 
524         /*!\brief Keyframe placement mode
525          *
526          * This value indicates whether the encoder should place keyframes at a
527          * fixed interval, or determine the optimal placement automatically
528          * (as governed by the #kf_min_dist and #kf_max_dist parameters)
529          */
530         enum vpx_kf_mode       kf_mode;
531 
532 
533         /*!\brief Keyframe minimum interval
534          *
535          * This value, expressed as a number of frames, prevents the encoder from
536          * placing a keyframe nearer than kf_min_dist to the previous keyframe. At
537          * least kf_min_dist frames non-keyframes will be coded before the next
538          * keyframe. Set kf_min_dist equal to kf_max_dist for a fixed interval.
539          */
540         unsigned int           kf_min_dist;
541 
542 
543         /*!\brief Keyframe maximum interval
544          *
545          * This value, expressed as a number of frames, forces the encoder to code
546          * a keyframe if one has not been coded in the last kf_max_dist frames.
547          * A value of 0 implies all frames will be keyframes. Set kf_min_dist
548          * equal to kf_max_dist for a fixed interval.
549          */
550         unsigned int           kf_max_dist;
551 
552     } vpx_codec_enc_cfg_t; /**< alias for struct vpx_codec_enc_cfg */
553 
554 
555     /*!\brief Initialize an encoder instance
556      *
557      * Initializes a encoder context using the given interface. Applications
558      * should call the vpx_codec_enc_init convenience macro instead of this
559      * function directly, to ensure that the ABI version number parameter
560      * is properly initialized.
561      *
562      * In XMA mode (activated by setting VPX_CODEC_USE_XMA in the flags
563      * parameter), the storage pointed to by the cfg parameter must be
564      * kept readable and stable until all memory maps have been set.
565      *
566      * \param[in]    ctx     Pointer to this instance's context.
567      * \param[in]    iface   Pointer to the algorithm interface to use.
568      * \param[in]    cfg     Configuration to use, if known. May be NULL.
569      * \param[in]    flags   Bitfield of VPX_CODEC_USE_* flags
570      * \param[in]    ver     ABI version number. Must be set to
571      *                       VPX_ENCODER_ABI_VERSION
572      * \retval #VPX_CODEC_OK
573      *     The decoder algorithm initialized.
574      * \retval #VPX_CODEC_MEM_ERROR
575      *     Memory allocation failed.
576      */
577     vpx_codec_err_t vpx_codec_enc_init_ver(vpx_codec_ctx_t      *ctx,
578                                            vpx_codec_iface_t    *iface,
579                                            vpx_codec_enc_cfg_t  *cfg,
580                                            vpx_codec_flags_t     flags,
581                                            int                   ver);
582 
583 
584     /*!\brief Convenience macro for vpx_codec_enc_init_ver()
585      *
586      * Ensures the ABI version parameter is properly set.
587      */
588 #define vpx_codec_enc_init(ctx, iface, cfg, flags) \
589     vpx_codec_enc_init_ver(ctx, iface, cfg, flags, VPX_ENCODER_ABI_VERSION)
590 
591 
592     /*!\brief Get a default configuration
593      *
594      * Initializes a encoder configuration structure with default values. Supports
595      * the notion of "usages" so that an algorithm may offer different default
596      * settings depending on the user's intended goal. This function \ref SHOULD
597      * be called by all applications to initialize the configuration structure
598      * before specializing the configuration with application specific values.
599      *
600      * \param[in]    iface   Pointer to the algorithm interface to use.
601      * \param[out]   cfg     Configuration buffer to populate
602      * \param[in]    usage   End usage. Set to 0 or use codec specific values.
603      *
604      * \retval #VPX_CODEC_OK
605      *     The configuration was populated.
606      * \retval #VPX_CODEC_INCAPABLE
607      *     Interface is not an encoder interface.
608      * \retval #VPX_CODEC_INVALID_PARAM
609      *     A parameter was NULL, or the usage value was not recognized.
610      */
611     vpx_codec_err_t  vpx_codec_enc_config_default(vpx_codec_iface_t    *iface,
612             vpx_codec_enc_cfg_t  *cfg,
613             unsigned int          usage);
614 
615 
616     /*!\brief Set or change configuration
617      *
618      * Reconfigures an encoder instance according to the given configuration.
619      *
620      * \param[in]    ctx     Pointer to this instance's context
621      * \param[in]    cfg     Configuration buffer to use
622      *
623      * \retval #VPX_CODEC_OK
624      *     The configuration was populated.
625      * \retval #VPX_CODEC_INCAPABLE
626      *     Interface is not an encoder interface.
627      * \retval #VPX_CODEC_INVALID_PARAM
628      *     A parameter was NULL, or the usage value was not recognized.
629      */
630     vpx_codec_err_t  vpx_codec_enc_config_set(vpx_codec_ctx_t            *ctx,
631             const vpx_codec_enc_cfg_t  *cfg);
632 
633 
634     /*!\brief Get global stream headers
635      *
636      * Retrieves a stream level global header packet, if supported by the codec.
637      *
638      * \param[in]    ctx     Pointer to this instance's context
639      *
640      * \retval NULL
641      *     Encoder does not support global header
642      * \retval Non-NULL
643      *     Pointer to buffer containing global header packet
644      */
645     vpx_fixed_buf_t *vpx_codec_get_global_headers(vpx_codec_ctx_t   *ctx);
646 
647 
648 #define VPX_DL_REALTIME     (1)        /**< deadline parameter analogous to
649     *   VPx REALTIME mode. */
650 #define VPX_DL_GOOD_QUALITY (1000000)  /**< deadline parameter analogous to
651     *   VPx GOOD QUALITY mode. */
652 #define VPX_DL_BEST_QUALITY (0)        /**< deadline parameter analogous to
653     *   VPx BEST QUALITY mode. */
654     /*!\brief Encode a frame
655      *
656      * Encodes a video frame at the given "presentation time." The presentation
657      * time stamp (PTS) \ref MUST be strictly increasing.
658      *
659      * The encoder supports the notion of a soft real-time deadline. Given a
660      * non-zero value to the deadline parameter, the encoder will make a "best
661      * effort" guarantee to  return before the given time slice expires. It is
662      * implicit that limiting the available time to encode will degrade the
663      * output quality. The encoder can be given an unlimited time to produce the
664      * best possible frame by specifying a deadline of '0'. This deadline
665      * supercedes the VPx notion of "best quality, good quality, realtime".
666      * Applications that wish to map these former settings to the new deadline
667      * based system can use the symbols #VPX_DL_REALTIME, #VPX_DL_GOOD_QUALITY,
668      * and #VPX_DL_BEST_QUALITY.
669      *
670      * When the last frame has been passed to the encoder, this function should
671      * continue to be called, with the img parameter set to NULL. This will
672      * signal the end-of-stream condition to the encoder and allow it to encode
673      * any held buffers. Encoding is complete when vpx_codec_encode() is called
674      * and vpx_codec_get_cx_data() returns no data.
675      *
676      * \param[in]    ctx       Pointer to this instance's context
677      * \param[in]    img       Image data to encode, NULL to flush.
678      * \param[in]    pts       Presentation time stamp, in timebase units.
679      * \param[in]    duration  Duration to show frame, in timebase units.
680      * \param[in]    flags     Flags to use for encoding this frame.
681      * \param[in]    deadline  Time to spend encoding, in microseconds. (0=infinite)
682      *
683      * \retval #VPX_CODEC_OK
684      *     The configuration was populated.
685      * \retval #VPX_CODEC_INCAPABLE
686      *     Interface is not an encoder interface.
687      * \retval #VPX_CODEC_INVALID_PARAM
688      *     A parameter was NULL, the image format is unsupported, etc.
689      */
690     vpx_codec_err_t  vpx_codec_encode(vpx_codec_ctx_t            *ctx,
691                                       const vpx_image_t          *img,
692                                       vpx_codec_pts_t             pts,
693                                       unsigned long               duration,
694                                       vpx_enc_frame_flags_t       flags,
695                                       unsigned long               deadline);
696 
697 
698     /*!\brief Set compressed data output buffer
699      *
700      * Sets the buffer that the codec should output the compressed data
701      * into. This call effectively sets the buffer pointer returned in the
702      * next VPX_CODEC_CX_FRAME_PKT packet. Subsequent packets will be
703      * appended into this buffer. The buffer is preserved across frames,
704      * so applications must periodically call this function after flushing
705      * the accumulated compressed data to disk or to the network to reset
706      * the pointer to the buffer's head.
707      *
708      * `pad_before` bytes will be skipped before writing the compressed
709      * data, and `pad_after` bytes will be appended to the packet. The size
710      * of the packet will be the sum of the size of the actual compressed
711      * data, pad_before, and pad_after. The padding bytes will be preserved
712      * (not overwritten).
713      *
714      * Note that calling this function does not guarantee that the returned
715      * compressed data will be placed into the specified buffer. In the
716      * event that the encoded data will not fit into the buffer provided,
717      * the returned packet \ref MAY point to an internal buffer, as it would
718      * if this call were never used. In this event, the output packet will
719      * NOT have any padding, and the application must free space and copy it
720      * to the proper place. This is of particular note in configurations
721      * that may output multiple packets for a single encoded frame (e.g., lagged
722      * encoding) or if the application does not reset the buffer periodically.
723      *
724      * Applications may restore the default behavior of the codec providing
725      * the compressed data buffer by calling this function with a NULL
726      * buffer.
727      *
728      * Applications \ref MUSTNOT call this function during iteration of
729      * vpx_codec_get_cx_data().
730      *
731      * \param[in]    ctx         Pointer to this instance's context
732      * \param[in]    buf         Buffer to store compressed data into
733      * \param[in]    pad_before  Bytes to skip before writing compressed data
734      * \param[in]    pad_after   Bytes to skip after writing compressed data
735      *
736      * \retval #VPX_CODEC_OK
737      *     The buffer was set successfully.
738      * \retval #VPX_CODEC_INVALID_PARAM
739      *     A parameter was NULL, the image format is unsupported, etc.
740      */
741     vpx_codec_err_t vpx_codec_set_cx_data_buf(vpx_codec_ctx_t       *ctx,
742             const vpx_fixed_buf_t *buf,
743             unsigned int           pad_before,
744             unsigned int           pad_after);
745 
746 
747     /*!\brief Encoded data iterator
748      *
749      * Iterates over a list of data packets to be passed from the encoder to the
750      * application. The different kinds of packets available are enumerated in
751      * #vpx_codec_cx_pkt_kind.
752      *
753      * #VPX_CODEC_CX_FRAME_PKT packets should be passed to the application's
754      * muxer. Multiple compressed frames may be in the list.
755      * #VPX_CODEC_STATS_PKT packets should be appended to a global buffer.
756      *
757      * The application \ref MUST silently ignore any packet kinds that it does
758      * not recognize or support.
759      *
760      * The data buffers returned from this function are only guaranteed to be
761      * valid until the application makes another call to any vpx_codec_* function.
762      *
763      * \param[in]     ctx      Pointer to this instance's context
764      * \param[in,out] iter     Iterator storage, initialized to NULL
765      *
766      * \return Returns a pointer to an output data packet (compressed frame data,
767      *         two-pass statistics, etc.) or NULL to signal end-of-list.
768      *
769      */
770     const vpx_codec_cx_pkt_t *vpx_codec_get_cx_data(vpx_codec_ctx_t   *ctx,
771             vpx_codec_iter_t  *iter);
772 
773 
774     /*!\brief Get Preview Frame
775      *
776      * Returns an image that can be used as a preview. Shows the image as it would
777      * exist at the decompressor. The application \ref MUST NOT write into this
778      * image buffer.
779      *
780      * \param[in]     ctx      Pointer to this instance's context
781      *
782      * \return Returns a pointer to a preview image, or NULL if no image is
783      *         available.
784      *
785      */
786     const vpx_image_t *vpx_codec_get_preview_frame(vpx_codec_ctx_t   *ctx);
787 
788 
789     /*!@} - end defgroup encoder*/
790 
791 #endif
792 #ifdef __cplusplus
793 }
794 #endif
795