1/*
2 * Copyright (c) 2019 James Almer <jamrial@gmail.com>
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 * This bitstream filter splits AV1 Temporal Units into packets containing
24 * just one frame, plus any leading and trailing OBUs that may be present at
25 * the beginning or end, respectively.
26 *
27 * Temporal Units already containing only one frame will be passed through
28 * unchanged. When splitting can't be performed, the Temporal Unit will be
29 * passed through containing only the remaining OBUs starting from the first
30 * one after the last successfully split frame.
31 */
32
33#include "libavutil/avassert.h"
34
35#include "bsf.h"
36#include "bsf_internal.h"
37#include "cbs.h"
38#include "cbs_av1.h"
39
40typedef struct AV1FSplitContext {
41    AVPacket *buffer_pkt;
42    CodedBitstreamContext *cbc;
43    CodedBitstreamFragment temporal_unit;
44
45    int nb_frames;
46    int cur_frame;
47    int cur_frame_idx;
48    int last_frame_idx;
49} AV1FSplitContext;
50
51static int av1_frame_split_filter(AVBSFContext *ctx, AVPacket *out)
52{
53    AV1FSplitContext *s = ctx->priv_data;
54    CodedBitstreamFragment *td = &s->temporal_unit;
55    int i, ret;
56    int split = !!s->buffer_pkt->data;
57
58    if (!s->buffer_pkt->data) {
59        int nb_frames = 0;
60
61        ret = ff_bsf_get_packet_ref(ctx, s->buffer_pkt);
62        if (ret < 0)
63            return ret;
64
65        ret = ff_cbs_read_packet(s->cbc, td, s->buffer_pkt);
66        if (ret < 0) {
67            av_log(ctx, AV_LOG_WARNING, "Failed to parse temporal unit.\n");
68            goto passthrough;
69        }
70
71        for (i = 0; i < td->nb_units; i++) {
72            CodedBitstreamUnit *unit = &td->units[i];
73
74            if (unit->type == AV1_OBU_FRAME ||
75                unit->type == AV1_OBU_FRAME_HEADER)
76                nb_frames++;
77            else if (unit->type == AV1_OBU_TILE_LIST) {
78                av_log(ctx, AV_LOG_VERBOSE, "Large scale tiles are unsupported.\n");
79                goto passthrough;
80            }
81        }
82        if (nb_frames > 1) {
83            s->cur_frame = 0;
84            s->cur_frame_idx = s->last_frame_idx = 0;
85            s->nb_frames = nb_frames;
86            split = 1;
87        }
88    }
89
90    if (split) {
91        AV1RawFrameHeader *frame = NULL;
92        int cur_frame_type = -1, size = 0;
93
94        for (i = s->cur_frame_idx; i < td->nb_units; i++) {
95            CodedBitstreamUnit *unit = &td->units[i];
96
97            size += unit->data_size;
98            if (unit->type == AV1_OBU_FRAME) {
99                AV1RawOBU *obu = unit->content;
100
101                if (frame) {
102                    av_log(ctx, AV_LOG_WARNING, "Frame OBU found when Tile data for a "
103                                                "previous frame was expected.\n");
104                    goto passthrough;
105                }
106
107                frame = &obu->obu.frame.header;
108                cur_frame_type = obu->header.obu_type;
109                s->last_frame_idx = s->cur_frame_idx;
110                s->cur_frame_idx  = i + 1;
111                s->cur_frame++;
112
113                // split here unless it's the last frame, in which case
114                // include every trailing OBU
115                if (s->cur_frame < s->nb_frames)
116                    break;
117            } else if (unit->type == AV1_OBU_FRAME_HEADER) {
118                AV1RawOBU *obu = unit->content;
119
120                if (frame) {
121                    av_log(ctx, AV_LOG_WARNING, "Frame Header OBU found when Tile data for a "
122                                                "previous frame was expected.\n");
123                    goto passthrough;
124                }
125
126                frame = &obu->obu.frame_header;
127                cur_frame_type = obu->header.obu_type;
128                s->last_frame_idx = s->cur_frame_idx;
129                s->cur_frame++;
130
131                // split here if show_existing_frame unless it's the last
132                // frame, in which case include every trailing OBU
133                if (frame->show_existing_frame &&
134                    s->cur_frame < s->nb_frames) {
135                    s->cur_frame_idx = i + 1;
136                    break;
137                }
138            } else if (unit->type == AV1_OBU_TILE_GROUP) {
139                AV1RawOBU *obu = unit->content;
140                AV1RawTileGroup *group = &obu->obu.tile_group;
141
142                if (!frame || cur_frame_type != AV1_OBU_FRAME_HEADER) {
143                    av_log(ctx, AV_LOG_WARNING, "Unexpected Tile Group OBU found before a "
144                                                "Frame Header.\n");
145                    goto passthrough;
146                }
147
148                if ((group->tg_end == (frame->tile_cols * frame->tile_rows) - 1) &&
149                    // include every trailing OBU with the last frame
150                    s->cur_frame < s->nb_frames) {
151                    s->cur_frame_idx = i + 1;
152                    break;
153                }
154            }
155        }
156        av_assert0(frame && s->cur_frame <= s->nb_frames);
157
158        ret = av_packet_ref(out, s->buffer_pkt);
159        if (ret < 0)
160            goto fail;
161
162        out->data = (uint8_t *)td->units[s->last_frame_idx].data;
163        out->size = size;
164
165        // skip the frame in the buffer packet if it's split successfully, so it's not present
166        // if the packet is passed through in case of failure when splitting another frame.
167        s->buffer_pkt->data += size;
168        s->buffer_pkt->size -= size;
169
170        if (!frame->show_existing_frame && !frame->show_frame)
171            out->pts = AV_NOPTS_VALUE;
172
173        if (s->cur_frame == s->nb_frames) {
174            av_packet_unref(s->buffer_pkt);
175            ff_cbs_fragment_reset(td);
176        }
177
178        return 0;
179    }
180
181passthrough:
182    av_packet_move_ref(out, s->buffer_pkt);
183
184    ret = 0;
185fail:
186    if (ret < 0) {
187        av_packet_unref(out);
188        av_packet_unref(s->buffer_pkt);
189    }
190    ff_cbs_fragment_reset(td);
191
192    return ret;
193}
194
195static const CodedBitstreamUnitType decompose_unit_types[] = {
196    AV1_OBU_TEMPORAL_DELIMITER,
197    AV1_OBU_SEQUENCE_HEADER,
198    AV1_OBU_FRAME_HEADER,
199    AV1_OBU_TILE_GROUP,
200    AV1_OBU_FRAME,
201};
202
203static int av1_frame_split_init(AVBSFContext *ctx)
204{
205    AV1FSplitContext *s = ctx->priv_data;
206    CodedBitstreamFragment *td = &s->temporal_unit;
207    int ret;
208
209    s->buffer_pkt = av_packet_alloc();
210    if (!s->buffer_pkt)
211        return AVERROR(ENOMEM);
212
213    ret = ff_cbs_init(&s->cbc, AV_CODEC_ID_AV1, ctx);
214    if (ret < 0)
215        return ret;
216
217    s->cbc->decompose_unit_types    = decompose_unit_types;
218    s->cbc->nb_decompose_unit_types = FF_ARRAY_ELEMS(decompose_unit_types);
219
220    if (!ctx->par_in->extradata_size)
221        return 0;
222
223    ret = ff_cbs_read_extradata(s->cbc, td, ctx->par_in);
224    if (ret < 0)
225        av_log(ctx, AV_LOG_WARNING, "Failed to parse extradata.\n");
226
227    ff_cbs_fragment_reset(td);
228
229    return 0;
230}
231
232static void av1_frame_split_flush(AVBSFContext *ctx)
233{
234    AV1FSplitContext *s = ctx->priv_data;
235
236    av_packet_unref(s->buffer_pkt);
237    ff_cbs_fragment_reset(&s->temporal_unit);
238}
239
240static void av1_frame_split_close(AVBSFContext *ctx)
241{
242    AV1FSplitContext *s = ctx->priv_data;
243
244    av_packet_free(&s->buffer_pkt);
245    ff_cbs_fragment_free(&s->temporal_unit);
246    ff_cbs_close(&s->cbc);
247}
248
249static const enum AVCodecID av1_frame_split_codec_ids[] = {
250    AV_CODEC_ID_AV1, AV_CODEC_ID_NONE,
251};
252
253const FFBitStreamFilter ff_av1_frame_split_bsf = {
254    .p.name         = "av1_frame_split",
255    .p.codec_ids    = av1_frame_split_codec_ids,
256    .priv_data_size = sizeof(AV1FSplitContext),
257    .init           = av1_frame_split_init,
258    .flush          = av1_frame_split_flush,
259    .close          = av1_frame_split_close,
260    .filter         = av1_frame_split_filter,
261};
262