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#include <inttypes.h>
20
21#include "libavutil/log.h"
22
23#include "bsf.h"
24#include "bsf_internal.h"
25#include "cbs.h"
26#include "cbs_bsf.h"
27#include "cbs_h264.h"
28#include "codec_id.h"
29#include "h264.h"
30#include "packet.h"
31
32#define NEW_GLOBAL_PIC_INIT_QP 26
33
34typedef struct H264RedundantPPSContext {
35    CBSBSFContext common;
36} H264RedundantPPSContext;
37
38
39static int h264_redundant_pps_fixup_pps(H264RedundantPPSContext *ctx,
40                                        CodedBitstreamUnit *unit)
41{
42    H264RawPPS *pps;
43    int err;
44
45    // The changes we are about to perform affect the parsing process,
46    // so we must make sure that the PPS is writable, otherwise the
47    // parsing of future slices will be incorrect and even raise errors.
48    err = ff_cbs_make_unit_writable(ctx->common.input, unit);
49    if (err < 0)
50        return err;
51    pps = unit->content;
52
53    // Overwrite pic_init_qp with the global value.
54    pps->pic_init_qp_minus26 = NEW_GLOBAL_PIC_INIT_QP - 26;
55
56    // Some PPSs have this set, so it must be set in all of them.
57    // (Slices which do not use such a PPS on input will still have
58    // *_weight_l*flag as zero and therefore write equivalently.)
59    pps->weighted_pred_flag = 1;
60
61    return 0;
62}
63
64static int h264_redundant_pps_fixup_slice(H264RedundantPPSContext *ctx,
65                                          H264RawSliceHeader *slice)
66{
67    const CodedBitstreamH264Context *const in = ctx->common.input->priv_data;
68    const H264RawPPS *const pps = in->pps[slice->pic_parameter_set_id];
69
70    // We modified the PPS's qp value, now offset this by applying
71    // the negative offset to the slices.
72    slice->slice_qp_delta += pps->pic_init_qp_minus26
73                             - (NEW_GLOBAL_PIC_INIT_QP - 26);
74
75    return 0;
76}
77
78static int h264_redundant_pps_update_fragment(AVBSFContext *bsf,
79                                              AVPacket *pkt,
80                                              CodedBitstreamFragment *au)
81{
82    H264RedundantPPSContext *ctx = bsf->priv_data;
83    int au_has_sps;
84    int err, i;
85
86    au_has_sps = 0;
87    for (i = 0; i < au->nb_units; i++) {
88        CodedBitstreamUnit *nal = &au->units[i];
89
90        if (nal->type == H264_NAL_SPS)
91            au_has_sps = 1;
92        if (nal->type == H264_NAL_PPS) {
93            err = h264_redundant_pps_fixup_pps(ctx, nal);
94            if (err < 0)
95                return err;
96            if (!au_has_sps) {
97                av_log(bsf, AV_LOG_VERBOSE, "Deleting redundant PPS "
98                       "at %"PRId64".\n", pkt->pts);
99                ff_cbs_delete_unit(au, i);
100                i--;
101                continue;
102            }
103        }
104        if (nal->type == H264_NAL_SLICE ||
105            nal->type == H264_NAL_IDR_SLICE) {
106            H264RawSlice *slice = nal->content;
107            h264_redundant_pps_fixup_slice(ctx, &slice->header);
108        }
109    }
110
111    return 0;
112}
113
114static const CBSBSFType h264_redundant_pps_type = {
115    .codec_id        = AV_CODEC_ID_H264,
116    .fragment_name   = "access unit",
117    .unit_name       = "NAL unit",
118    .update_fragment = &h264_redundant_pps_update_fragment,
119};
120
121static int h264_redundant_pps_init(AVBSFContext *bsf)
122{
123    return ff_cbs_bsf_generic_init(bsf, &h264_redundant_pps_type);
124}
125
126static const enum AVCodecID h264_redundant_pps_codec_ids[] = {
127    AV_CODEC_ID_H264, AV_CODEC_ID_NONE,
128};
129
130const FFBitStreamFilter ff_h264_redundant_pps_bsf = {
131    .p.name         = "h264_redundant_pps",
132    .p.codec_ids    = h264_redundant_pps_codec_ids,
133    .priv_data_size = sizeof(H264RedundantPPSContext),
134    .init           = &h264_redundant_pps_init,
135    .close          = &ff_cbs_bsf_generic_close,
136    .filter         = &ff_cbs_bsf_generic_filter,
137};
138