video_enc_params.h (5991B)
1 /* 2 * This file is part of FFmpeg. 3 * 4 * FFmpeg is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU Lesser General Public 6 * License as published by the Free Software Foundation; either 7 * version 2.1 of the License, or (at your option) any later version. 8 * 9 * FFmpeg is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * Lesser General Public License for more details. 13 * 14 * You should have received a copy of the GNU Lesser General Public 15 * License along with FFmpeg; if not, write to the Free Software 16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 17 */ 18 19 #ifndef AVUTIL_VIDEO_ENC_PARAMS_H 20 #define AVUTIL_VIDEO_ENC_PARAMS_H 21 22 #include <stddef.h> 23 #include <stdint.h> 24 25 #include "libavutil/avassert.h" 26 #include "libavutil/frame.h" 27 28 enum AVVideoEncParamsType { 29 AV_VIDEO_ENC_PARAMS_NONE = -1, 30 /** 31 * VP9 stores: 32 * - per-frame base (luma AC) quantizer index, exported as AVVideoEncParams.qp 33 * - deltas for luma DC, chroma AC and chroma DC, exported in the 34 * corresponding entries in AVVideoEncParams.delta_qp 35 * - per-segment delta, exported as for each block as AVVideoBlockParams.delta_qp 36 * 37 * To compute the resulting quantizer index for a block: 38 * - for luma AC, add the base qp and the per-block delta_qp, saturating to 39 * unsigned 8-bit. 40 * - for luma DC and chroma AC/DC, add the corresponding 41 * AVVideoBlockParams.delta_qp to the luma AC index, again saturating to 42 * unsigned 8-bit. 43 */ 44 AV_VIDEO_ENC_PARAMS_VP9, 45 46 /** 47 * H.264 stores: 48 * - in PPS (per-picture): 49 * * initial QP_Y (luma) value, exported as AVVideoEncParams.qp 50 * * delta(s) for chroma QP values (same for both, or each separately), 51 * exported as in the corresponding entries in AVVideoEncParams.delta_qp 52 * - per-slice QP delta, not exported directly, added to the per-MB value 53 * - per-MB delta; not exported directly; the final per-MB quantizer 54 * parameter - QP_Y - minus the value in AVVideoEncParams.qp is exported 55 * as AVVideoBlockParams.qp_delta. 56 */ 57 AV_VIDEO_ENC_PARAMS_H264, 58 59 /* 60 * MPEG-2-compatible quantizer. 61 * 62 * Summing the frame-level qp with the per-block delta_qp gives the 63 * resulting quantizer for the block. 64 */ 65 AV_VIDEO_ENC_PARAMS_MPEG2, 66 }; 67 68 /** 69 * Video encoding parameters for a given frame. This struct is allocated along 70 * with an optional array of per-block AVVideoBlockParams descriptors. 71 * Must be allocated with av_video_enc_params_alloc(). 72 */ 73 typedef struct AVVideoEncParams { 74 /** 75 * Number of blocks in the array. 76 * 77 * May be 0, in which case no per-block information is present. In this case 78 * the values of blocks_offset / block_size are unspecified and should not 79 * be accessed. 80 */ 81 unsigned int nb_blocks; 82 /** 83 * Offset in bytes from the beginning of this structure at which the array 84 * of blocks starts. 85 */ 86 size_t blocks_offset; 87 /* 88 * Size of each block in bytes. May not match sizeof(AVVideoBlockParams). 89 */ 90 size_t block_size; 91 92 /** 93 * Type of the parameters (the codec they are used with). 94 */ 95 enum AVVideoEncParamsType type; 96 97 /** 98 * Base quantisation parameter for the frame. The final quantiser for a 99 * given block in a given plane is obtained from this value, possibly 100 * combined with {@code delta_qp} and the per-block delta in a manner 101 * documented for each type. 102 */ 103 int32_t qp; 104 105 /** 106 * Quantisation parameter offset from the base (per-frame) qp for a given 107 * plane (first index) and AC/DC coefficients (second index). 108 */ 109 int32_t delta_qp[4][2]; 110 } AVVideoEncParams; 111 112 /** 113 * Data structure for storing block-level encoding information. 114 * It is allocated as a part of AVVideoEncParams and should be retrieved with 115 * av_video_enc_params_block(). 116 * 117 * sizeof(AVVideoBlockParams) is not a part of the ABI and new fields may be 118 * added to it. 119 */ 120 typedef struct AVVideoBlockParams { 121 /** 122 * Distance in luma pixels from the top-left corner of the visible frame 123 * to the top-left corner of the block. 124 * Can be negative if top/right padding is present on the coded frame. 125 */ 126 int src_x, src_y; 127 /** 128 * Width and height of the block in luma pixels. 129 */ 130 int w, h; 131 132 /** 133 * Difference between this block's final quantization parameter and the 134 * corresponding per-frame value. 135 */ 136 int32_t delta_qp; 137 } AVVideoBlockParams; 138 139 /** 140 * Get the block at the specified {@code idx}. Must be between 0 and nb_blocks - 1. 141 */ 142 static av_always_inline AVVideoBlockParams* 143 av_video_enc_params_block(AVVideoEncParams *par, unsigned int idx) 144 { 145 av_assert0(idx < par->nb_blocks); 146 return (AVVideoBlockParams *)((uint8_t *)par + par->blocks_offset + 147 idx * par->block_size); 148 } 149 150 /** 151 * Allocates memory for AVVideoEncParams of the given type, plus an array of 152 * {@code nb_blocks} AVVideoBlockParams and initializes the variables. Can be 153 * freed with a normal av_free() call. 154 * 155 * @param out_size if non-NULL, the size in bytes of the resulting data array is 156 * written here. 157 */ 158 AVVideoEncParams *av_video_enc_params_alloc(enum AVVideoEncParamsType type, 159 unsigned int nb_blocks, size_t *out_size); 160 161 /** 162 * Allocates memory for AVEncodeInfoFrame plus an array of 163 * {@code nb_blocks} AVEncodeInfoBlock in the given AVFrame {@code frame} 164 * as AVFrameSideData of type AV_FRAME_DATA_VIDEO_ENC_PARAMS 165 * and initializes the variables. 166 */ 167 AVVideoEncParams* 168 av_video_enc_params_create_side_data(AVFrame *frame, enum AVVideoEncParamsType type, 169 unsigned int nb_blocks); 170 171 #endif /* AVUTIL_VIDEO_ENC_PARAMS_H */