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
28extern "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