Tristan Matthews | 0a329cc | 2013-07-17 13:20:14 -0400 | [diff] [blame] | 1 | /* $Id$ */ |
| 2 | /* |
| 3 | * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com) |
| 4 | * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License as published by |
| 8 | * the Free Software Foundation; either version 2 of the License, or |
| 9 | * (at your option) any later version. |
| 10 | * |
| 11 | * This program is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | * GNU General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU General Public License |
| 17 | * along with this program; if not, write to the Free Software |
| 18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 19 | */ |
| 20 | |
| 21 | #ifndef __PJMEDIA_DELAYBUF_H__ |
| 22 | #define __PJMEDIA_DELAYBUF_H__ |
| 23 | |
| 24 | |
| 25 | /** |
| 26 | * @file delaybuf.h |
| 27 | * @brief Delay Buffer. |
| 28 | */ |
| 29 | |
| 30 | #include <pjmedia/types.h> |
| 31 | |
| 32 | /** |
| 33 | * @defgroup PJMED_DELAYBUF Adaptive Delay Buffer |
| 34 | * @ingroup PJMEDIA_FRAME_OP |
| 35 | * @brief Adaptive delay buffer with high-quality time-scale |
| 36 | * modification |
| 37 | * @{ |
| 38 | * |
| 39 | * This section describes PJMEDIA's implementation of delay buffer. |
| 40 | * Delay buffer works quite similarly like a fixed jitter buffer, that |
| 41 | * is it will delay the frame retrieval by some interval so that caller |
| 42 | * will get continuous frame from the buffer. This can be useful when |
| 43 | * the put() and get() operations are not evenly interleaved, for example |
| 44 | * when caller performs burst of put() operations and then followed by |
| 45 | * burst of get() operations. With using this delay buffer, the buffer |
| 46 | * will put the burst frames into a buffer so that get() operations |
| 47 | * will always get a frame from the buffer (assuming that the number of |
| 48 | * get() and put() are matched). |
| 49 | * |
| 50 | * The buffer is adaptive, that is it continuously learns the optimal delay |
| 51 | * to be applied to the audio flow at run-time. Once the optimal delay has |
| 52 | * been learned, the delay buffer will apply this delay to the audio flow, |
| 53 | * expanding or shrinking the audio samples as necessary when the actual |
| 54 | * audio samples in the buffer are too low or too high. It does this without |
| 55 | * distorting the audio quality of the audio, by using \a PJMED_WSOLA. |
| 56 | * |
| 57 | * The delay buffer is used in \ref PJMED_SND_PORT, \ref PJMEDIA_SPLITCOMB, |
| 58 | * and \ref PJMEDIA_CONF. |
| 59 | */ |
| 60 | |
| 61 | PJ_BEGIN_DECL |
| 62 | |
| 63 | /** Opaque declaration for delay buffer. */ |
| 64 | typedef struct pjmedia_delay_buf pjmedia_delay_buf; |
| 65 | |
| 66 | /** |
| 67 | * Delay buffer options. |
| 68 | */ |
| 69 | typedef enum pjmedia_delay_buf_flag |
| 70 | { |
| 71 | /** |
| 72 | * Use simple FIFO mechanism for the delay buffer, i.e. |
| 73 | * without WSOLA for expanding and shrinking audio samples. |
| 74 | */ |
| 75 | PJMEDIA_DELAY_BUF_SIMPLE_FIFO = 1 |
| 76 | |
| 77 | } pjmedia_delay_buf_flag; |
| 78 | |
| 79 | /** |
| 80 | * Create the delay buffer. Once the delay buffer is created, it will |
| 81 | * enter learning state unless the delay argument is specified, which |
| 82 | * in this case it will directly enter the running state. |
| 83 | * |
| 84 | * @param pool Pool where the delay buffer will be allocated |
| 85 | * from. |
| 86 | * @param name Optional name for the buffer for log |
| 87 | * identification. |
| 88 | * @param clock_rate Number of samples processed per second. |
| 89 | * @param samples_per_frame Number of samples per frame. |
| 90 | * @param channel_count Number of channel per frame. |
| 91 | * @param max_delay Maximum number of delay to be accommodated, |
| 92 | * in ms, if this value is negative or less than |
| 93 | * one frame time, default maximum delay used is |
| 94 | * 400 ms. |
| 95 | * @param options Options. If PJMEDIA_DELAY_BUF_SIMPLE_FIFO is |
| 96 | * specified, then a simple FIFO mechanism |
| 97 | * will be used instead of the adaptive |
| 98 | * implementation (which uses WSOLA to expand |
| 99 | * or shrink audio samples). |
| 100 | * See #pjmedia_delay_buf_flag for other options. |
| 101 | * @param p_b Pointer to receive the delay buffer instance. |
| 102 | * |
| 103 | * @return PJ_SUCCESS if the delay buffer has been |
| 104 | * created successfully, otherwise the appropriate |
| 105 | * error will be returned. |
| 106 | */ |
| 107 | PJ_DECL(pj_status_t) pjmedia_delay_buf_create(pj_pool_t *pool, |
| 108 | const char *name, |
| 109 | unsigned clock_rate, |
| 110 | unsigned samples_per_frame, |
| 111 | unsigned channel_count, |
| 112 | unsigned max_delay, |
| 113 | unsigned options, |
| 114 | pjmedia_delay_buf **p_b); |
| 115 | |
| 116 | /** |
| 117 | * Put one frame into the buffer. |
| 118 | * |
| 119 | * @param b The delay buffer. |
| 120 | * @param frame Frame to be put into the buffer. This frame |
| 121 | * must have samples_per_frame length. |
| 122 | * |
| 123 | * @return PJ_SUCCESS if frames can be put successfully. |
| 124 | * PJ_EPENDING if the buffer is still at learning |
| 125 | * state. PJ_ETOOMANY if the number of frames |
| 126 | * will exceed maximum delay level, which in this |
| 127 | * case the new frame will overwrite the oldest |
| 128 | * frame in the buffer. |
| 129 | */ |
| 130 | PJ_DECL(pj_status_t) pjmedia_delay_buf_put(pjmedia_delay_buf *b, |
| 131 | pj_int16_t frame[]); |
| 132 | |
| 133 | /** |
| 134 | * Get one frame from the buffer. |
| 135 | * |
| 136 | * @param b The delay buffer. |
| 137 | * @param frame Buffer to receive the frame from the delay |
| 138 | * buffer. |
| 139 | * |
| 140 | * @return PJ_SUCCESS if frame has been copied successfully. |
| 141 | * PJ_EPENDING if no frame is available, either |
| 142 | * because the buffer is still at learning state or |
| 143 | * no buffer is available during running state. |
| 144 | * On non-successful return, the frame will be |
| 145 | * filled with zeroes. |
| 146 | */ |
| 147 | PJ_DECL(pj_status_t) pjmedia_delay_buf_get(pjmedia_delay_buf *b, |
| 148 | pj_int16_t frame[]); |
| 149 | |
| 150 | /** |
| 151 | * Reset delay buffer. This will clear the buffer's content. But keep |
| 152 | * the learning result. |
| 153 | * |
| 154 | * @param b The delay buffer. |
| 155 | * |
| 156 | * @return PJ_SUCCESS on success or the appropriate error. |
| 157 | */ |
| 158 | PJ_DECL(pj_status_t) pjmedia_delay_buf_reset(pjmedia_delay_buf *b); |
| 159 | |
| 160 | /** |
| 161 | * Destroy delay buffer. |
| 162 | * |
| 163 | * @param b Delay buffer session. |
| 164 | * |
| 165 | * @return PJ_SUCCESS normally. |
| 166 | */ |
| 167 | PJ_DECL(pj_status_t) pjmedia_delay_buf_destroy(pjmedia_delay_buf *b); |
| 168 | |
| 169 | |
| 170 | PJ_END_DECL |
| 171 | |
| 172 | /** |
| 173 | * @} |
| 174 | */ |
| 175 | |
| 176 | #endif /* __PJMEDIA_DELAYBUF_H__ */ |