xref: /third_party/ffmpeg/libavcodec/setts_bsf.c (revision cabdff1a) 
1/*
2 * Copyright (c) 2021 Paul B Mahol
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/**
22 * @file
23 * Change the PTS/DTS timestamps.
24 */
25
26#include "libavutil/opt.h"
27#include "libavutil/eval.h"
28
29#include "bsf.h"
30#include "bsf_internal.h"
31
32static const char *const var_names[] = {
33    "N",           ///< frame number (starting at zero)
34    "TS",
35    "POS",         ///< original position in the file of the frame
36    "PREV_INPTS",  ///< previous  input PTS
37    "PREV_INDTS",  ///< previous  input DTS
38    "PREV_INDURATION", ///< previous input duration
39    "PREV_OUTPTS", ///< previous output PTS
40    "PREV_OUTDTS", ///< previous output DTS
41    "PREV_OUTDURATION", ///< previous output duration
42    "NEXT_PTS",    ///< next input PTS
43    "NEXT_DTS",    ///< next input DTS
44    "NEXT_DURATION", ///< next input duration
45    "PTS",         ///< original PTS in the file of the frame
46    "DTS",         ///< original DTS in the file of the frame
47    "DURATION",    ///< original duration in the file of the frame
48    "STARTPTS",    ///< PTS at start of movie
49    "STARTDTS",    ///< DTS at start of movie
50    "TB",          ///< input timebase of the stream
51    "TB_OUT",      ///< output timebase of the stream
52    "SR",          ///< sample rate of the stream
53    "NOPTS",       ///< The AV_NOPTS_VALUE constant
54    NULL
55};
56
57enum var_name {
58    VAR_N,
59    VAR_TS,
60    VAR_POS,
61    VAR_PREV_INPTS,
62    VAR_PREV_INDTS,
63    VAR_PREV_INDUR,
64    VAR_PREV_OUTPTS,
65    VAR_PREV_OUTDTS,
66    VAR_PREV_OUTDUR,
67    VAR_NEXT_PTS,
68    VAR_NEXT_DTS,
69    VAR_NEXT_DUR,
70    VAR_PTS,
71    VAR_DTS,
72    VAR_DURATION,
73    VAR_STARTPTS,
74    VAR_STARTDTS,
75    VAR_TB,
76    VAR_TB_OUT,
77    VAR_SR,
78    VAR_NOPTS,
79    VAR_VARS_NB
80};
81
82typedef struct SetTSContext {
83    const AVClass *class;
84
85    char *ts_str;
86    char *pts_str;
87    char *dts_str;
88    char *duration_str;
89
90    AVRational time_base;
91
92    int64_t frame_number;
93
94    double var_values[VAR_VARS_NB];
95
96    AVExpr *ts_expr;
97    AVExpr *pts_expr;
98    AVExpr *dts_expr;
99    AVExpr *duration_expr;
100
101    AVPacket *prev_inpkt;
102    AVPacket *prev_outpkt;
103    AVPacket *cur_pkt;
104} SetTSContext;
105
106static int setts_init(AVBSFContext *ctx)
107{
108    SetTSContext *s = ctx->priv_data;
109    int ret;
110
111    s->prev_inpkt = av_packet_alloc();
112    s->prev_outpkt = av_packet_alloc();
113    s->cur_pkt = av_packet_alloc();
114    if (!s->prev_inpkt || !s->prev_outpkt || !s->cur_pkt)
115        return AVERROR(ENOMEM);
116
117    if ((ret = av_expr_parse(&s->ts_expr, s->ts_str,
118                             var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
119        av_log(ctx, AV_LOG_ERROR, "Error while parsing ts expression '%s'\n", s->ts_str);
120        return ret;
121    }
122
123    if ((ret = av_expr_parse(&s->duration_expr, s->duration_str,
124                             var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
125        av_log(ctx, AV_LOG_ERROR, "Error while parsing duration expression '%s'\n", s->duration_str);
126        return ret;
127    }
128
129    if (s->pts_str) {
130        if ((ret = av_expr_parse(&s->pts_expr, s->pts_str,
131                                 var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
132            av_log(ctx, AV_LOG_ERROR, "Error while parsing pts expression '%s'\n", s->pts_str);
133            return ret;
134        }
135    }
136
137    if (s->dts_str) {
138        if ((ret = av_expr_parse(&s->dts_expr, s->dts_str,
139                                 var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
140            av_log(ctx, AV_LOG_ERROR, "Error while parsing dts expression '%s'\n", s->dts_str);
141            return ret;
142        }
143    }
144
145    if (s->time_base.num > 0 && s->time_base.den > 0)
146        ctx->time_base_out = s->time_base;
147
148    s->frame_number= 0;
149    s->var_values[VAR_STARTPTS] = AV_NOPTS_VALUE;
150    s->var_values[VAR_STARTDTS] = AV_NOPTS_VALUE;
151    s->var_values[VAR_NOPTS] = AV_NOPTS_VALUE;
152    s->var_values[VAR_TB]    = ctx->time_base_in.den ? av_q2d(ctx->time_base_in) : 0;
153    s->var_values[VAR_TB_OUT]= ctx->time_base_out.den ? av_q2d(ctx->time_base_out) : 0;
154    s->var_values[VAR_SR]    = ctx->par_in->sample_rate;
155
156    return 0;
157}
158
159static int setts_filter(AVBSFContext *ctx, AVPacket *pkt)
160{
161    SetTSContext *s = ctx->priv_data;
162    int64_t new_ts, new_pts, new_dts, new_duration;
163    int ret;
164
165    ret = ff_bsf_get_packet_ref(ctx, pkt);
166    if (ret < 0 && (ret != AVERROR_EOF || !s->cur_pkt->data))
167        return ret;
168
169    if (!s->cur_pkt->data) {
170         av_packet_move_ref(s->cur_pkt, pkt);
171         return AVERROR(EAGAIN);
172    }
173
174    if (s->var_values[VAR_STARTPTS] == AV_NOPTS_VALUE)
175        s->var_values[VAR_STARTPTS] = s->cur_pkt->pts;
176
177    if (s->var_values[VAR_STARTDTS] == AV_NOPTS_VALUE)
178        s->var_values[VAR_STARTDTS] = s->cur_pkt->dts;
179
180    s->var_values[VAR_N]           = s->frame_number++;
181    s->var_values[VAR_TS]          = s->cur_pkt->dts;
182    s->var_values[VAR_POS]         = s->cur_pkt->pos;
183    s->var_values[VAR_PTS]         = s->cur_pkt->pts;
184    s->var_values[VAR_DTS]         = s->cur_pkt->dts;
185    s->var_values[VAR_DURATION]    = s->cur_pkt->duration;
186    s->var_values[VAR_PREV_INPTS]  = s->prev_inpkt->pts;
187    s->var_values[VAR_PREV_INDTS]  = s->prev_inpkt->dts;
188    s->var_values[VAR_PREV_INDUR]  = s->prev_inpkt->duration;
189    s->var_values[VAR_PREV_OUTPTS] = s->prev_outpkt->pts;
190    s->var_values[VAR_PREV_OUTDTS] = s->prev_outpkt->dts;
191    s->var_values[VAR_PREV_OUTDUR] = s->prev_outpkt->duration;
192    s->var_values[VAR_NEXT_PTS]    = pkt->pts;
193    s->var_values[VAR_NEXT_DTS]    = pkt->dts;
194    s->var_values[VAR_NEXT_DUR]    = pkt->duration;
195
196    new_ts = llrint(av_expr_eval(s->ts_expr, s->var_values, NULL));
197    new_duration = llrint(av_expr_eval(s->duration_expr, s->var_values, NULL));
198
199    if (s->pts_str) {
200        s->var_values[VAR_TS] = s->cur_pkt->pts;
201        new_pts = llrint(av_expr_eval(s->pts_expr, s->var_values, NULL));
202    } else {
203        new_pts = new_ts;
204    }
205
206    if (s->dts_str) {
207        s->var_values[VAR_TS] = s->cur_pkt->dts;
208        new_dts = llrint(av_expr_eval(s->dts_expr, s->var_values, NULL));
209    } else {
210        new_dts = new_ts;
211    }
212
213    av_packet_unref(s->prev_inpkt);
214    av_packet_unref(s->prev_outpkt);
215    av_packet_move_ref(s->prev_inpkt, s->cur_pkt);
216    av_packet_move_ref(s->cur_pkt, pkt);
217
218    ret = av_packet_ref(pkt, s->prev_inpkt);
219    if (ret < 0)
220        return ret;
221
222    pkt->pts = new_pts;
223    pkt->dts = new_dts;
224    pkt->duration = new_duration;
225
226    ret = av_packet_ref(s->prev_outpkt, pkt);
227    if (ret < 0)
228        av_packet_unref(pkt);
229
230    return ret;
231}
232
233static void setts_close(AVBSFContext *bsf)
234{
235    SetTSContext *s = bsf->priv_data;
236
237    av_packet_free(&s->prev_inpkt);
238    av_packet_free(&s->prev_outpkt);
239    av_packet_free(&s->cur_pkt);
240
241    av_expr_free(s->ts_expr);
242    s->ts_expr = NULL;
243    av_expr_free(s->pts_expr);
244    s->pts_expr = NULL;
245    av_expr_free(s->dts_expr);
246    s->dts_expr = NULL;
247    av_expr_free(s->duration_expr);
248    s->duration_expr = NULL;
249}
250
251#define OFFSET(x) offsetof(SetTSContext, x)
252#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_SUBTITLE_PARAM|AV_OPT_FLAG_BSF_PARAM)
253
254static const AVOption options[] = {
255    { "ts",  "set expression for packet PTS and DTS", OFFSET(ts_str),  AV_OPT_TYPE_STRING, {.str="TS"}, 0, 0, FLAGS },
256    { "pts", "set expression for packet PTS", OFFSET(pts_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
257    { "dts", "set expression for packet DTS", OFFSET(dts_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
258    { "duration", "set expression for packet duration", OFFSET(duration_str), AV_OPT_TYPE_STRING, {.str="DURATION"}, 0, 0, FLAGS },
259    { "time_base", "set output timebase", OFFSET(time_base), AV_OPT_TYPE_RATIONAL, {.dbl=0}, 0, INT_MAX, FLAGS },
260    { NULL },
261};
262
263static const AVClass setts_class = {
264    .class_name = "setts_bsf",
265    .item_name  = av_default_item_name,
266    .option     = options,
267    .version    = LIBAVUTIL_VERSION_INT,
268};
269
270const FFBitStreamFilter ff_setts_bsf = {
271    .p.name         = "setts",
272    .p.priv_class   = &setts_class,
273    .priv_data_size = sizeof(SetTSContext),
274    .init           = setts_init,
275    .close          = setts_close,
276    .filter         = setts_filter,
277};
278