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1 /*
2  * Copyright (C) 2004 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg 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 GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include <math.h>
22 #include "libavutil/eval.h"
23 #include "libavutil/imgutils.h"
24 #include "libavutil/pixdesc.h"
25 #include "libavutil/opt.h"
26 #include "libavutil/video_enc_params.h"
27 
28 #include "avfilter.h"
29 #include "formats.h"
30 #include "internal.h"
31 #include "video.h"
32 
33 typedef struct QPContext {
34     const AVClass *class;
35     char *qp_expr_str;
36     int8_t lut[257];
37     int h, qstride;
38     int evaluate_per_mb;
39 } QPContext;
40 
41 static const char *const var_names[] = { "known", "qp", "x", "y", "w", "h", NULL };
42 
43 #define OFFSET(x) offsetof(QPContext, x)
44 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
45 
46 static const AVOption qp_options[] = {
47     { "qp", "set qp expression", OFFSET(qp_expr_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
48     { NULL }
49 };
50 
51 AVFILTER_DEFINE_CLASS(qp);
52 
config_input(AVFilterLink * inlink)53 static int config_input(AVFilterLink *inlink)
54 {
55     AVFilterContext *ctx = inlink->dst;
56     QPContext *s = ctx->priv;
57     int i;
58     int ret;
59     AVExpr *e = NULL;
60 
61     if (!s->qp_expr_str)
62         return 0;
63 
64     ret = av_expr_parse(&e, s->qp_expr_str, var_names, NULL, NULL, NULL, NULL, 0, ctx);
65     if (ret < 0)
66         return ret;
67 
68     s->h       = (inlink->h + 15) >> 4;
69     s->qstride = (inlink->w + 15) >> 4;
70     for (i = -129; i < 128; i++) {
71         double var_values[] = { i != -129, i, NAN, NAN, s->qstride, s->h, 0};
72         double temp_val = av_expr_eval(e, var_values, NULL);
73 
74         if (isnan(temp_val)) {
75             if(strchr(s->qp_expr_str, 'x') || strchr(s->qp_expr_str, 'y'))
76                 s->evaluate_per_mb = 1;
77             else {
78                 av_expr_free(e);
79                 return AVERROR(EINVAL);
80             }
81         }
82 
83         s->lut[i + 129] = lrintf(temp_val);
84     }
85     av_expr_free(e);
86 
87     return 0;
88 }
89 
filter_frame(AVFilterLink * inlink,AVFrame * in)90 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
91 {
92     AVFilterContext *ctx = inlink->dst;
93     AVFilterLink *outlink = ctx->outputs[0];
94     QPContext *s = ctx->priv;
95     AVFrame *out = NULL;
96     int ret;
97 
98     AVFrameSideData *sd_in;
99     AVVideoEncParams *par_in = NULL;
100     int8_t in_qp_global = 0;
101 
102     AVVideoEncParams *par_out;
103 
104     if (!s->qp_expr_str || ctx->is_disabled)
105         return ff_filter_frame(outlink, in);
106 
107     sd_in = av_frame_get_side_data(in, AV_FRAME_DATA_VIDEO_ENC_PARAMS);
108     if (sd_in && sd_in->size >= sizeof(AVVideoEncParams)) {
109         par_in = (AVVideoEncParams*)sd_in->data;
110 
111         // we accept the input QP table only if it is of the MPEG2 type
112         // and contains either no blocks at all or 16x16 macroblocks
113         if (par_in->type == AV_VIDEO_ENC_PARAMS_MPEG2 &&
114             (par_in->nb_blocks == s->h * s->qstride || !par_in->nb_blocks)) {
115             in_qp_global = par_in->qp;
116             if (!par_in->nb_blocks)
117                 par_in = NULL;
118         } else
119             par_in = NULL;
120     }
121 
122     out = av_frame_clone(in);
123     if (!out) {
124         ret = AVERROR(ENOMEM);
125         goto fail;
126     }
127 
128     par_out = av_video_enc_params_create_side_data(out, AV_VIDEO_ENC_PARAMS_MPEG2,
129                                                    (s->evaluate_per_mb || sd_in) ?
130                                                    s->h * s->qstride : 0);
131     if (!par_out) {
132         ret = AVERROR(ENOMEM);
133         goto fail;
134     }
135 
136 #define BLOCK_QP_DELTA(block_idx) \
137     (par_in ? av_video_enc_params_block(par_in, block_idx)->delta_qp : 0)
138 
139     if (s->evaluate_per_mb) {
140         int y, x;
141 
142         for (y = 0; y < s->h; y++)
143             for (x = 0; x < s->qstride; x++) {
144                 unsigned int block_idx = y * s->qstride + x;
145                 AVVideoBlockParams *b = av_video_enc_params_block(par_out, block_idx);
146                 int qp = sd_in ? in_qp_global + BLOCK_QP_DELTA(block_idx) : NAN;
147                 double var_values[] = { !!sd_in, qp, x, y, s->qstride, s->h, 0};
148                 double temp_val;
149 
150                 ret = av_expr_parse_and_eval(&temp_val, s->qp_expr_str,
151                                             var_names, var_values,
152                                             NULL, NULL, NULL, NULL, 0, 0, ctx);
153                 if (ret < 0)
154                     goto fail;
155                 b->delta_qp = lrintf(temp_val);
156             }
157     } else if (sd_in) {
158         int y, x;
159 
160         for (y = 0; y < s->h; y++)
161             for (x = 0; x < s->qstride; x++) {
162                 unsigned int block_idx = y * s->qstride + x;
163                 AVVideoBlockParams *b = av_video_enc_params_block(par_out, block_idx);
164                 b->delta_qp = s->lut[129 + (int8_t)(in_qp_global + BLOCK_QP_DELTA(block_idx))];
165             }
166     } else {
167         par_out->qp = s->lut[0];
168     }
169 
170     ret = ff_filter_frame(outlink, out);
171     out = NULL;
172 fail:
173     av_frame_free(&in);
174     av_frame_free(&out);
175     return ret;
176 }
177 
178 static const AVFilterPad qp_inputs[] = {
179     {
180         .name         = "default",
181         .type         = AVMEDIA_TYPE_VIDEO,
182         .filter_frame = filter_frame,
183         .config_props = config_input,
184     },
185 };
186 
187 static const AVFilterPad qp_outputs[] = {
188     {
189         .name = "default",
190         .type = AVMEDIA_TYPE_VIDEO,
191     },
192 };
193 
194 const AVFilter ff_vf_qp = {
195     .name          = "qp",
196     .description   = NULL_IF_CONFIG_SMALL("Change video quantization parameters."),
197     .priv_size     = sizeof(QPContext),
198     FILTER_INPUTS(qp_inputs),
199     FILTER_OUTPUTS(qp_outputs),
200     .priv_class    = &qp_class,
201     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL |
202                      AVFILTER_FLAG_METADATA_ONLY,
203 };
204