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path: root/libavcodec/h264_mp4toannexb_bsf.c (plain)
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1/*
2 * H.264 MP4 to Annex B byte stream format filter
3 * Copyright (c) 2007 Benoit Fouet <benoit.fouet@free.fr>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include <string.h>
23
24#include "libavutil/intreadwrite.h"
25#include "libavutil/mem.h"
26
27#include "avcodec.h"
28#include "bsf.h"
29
30typedef struct H264BSFContext {
31 int32_t sps_offset;
32 int32_t pps_offset;
33 uint8_t length_size;
34 uint8_t new_idr;
35 uint8_t idr_sps_seen;
36 uint8_t idr_pps_seen;
37 int extradata_parsed;
38} H264BSFContext;
39
40static int alloc_and_copy(AVPacket *out,
41 const uint8_t *sps_pps, uint32_t sps_pps_size,
42 const uint8_t *in, uint32_t in_size)
43{
44 uint32_t offset = out->size;
45 uint8_t nal_header_size = offset ? 3 : 4;
46 int err;
47
48 err = av_grow_packet(out, sps_pps_size + in_size + nal_header_size);
49 if (err < 0)
50 return err;
51
52 if (sps_pps)
53 memcpy(out->data + offset, sps_pps, sps_pps_size);
54 memcpy(out->data + sps_pps_size + nal_header_size + offset, in, in_size);
55 if (!offset) {
56 AV_WB32(out->data + sps_pps_size, 1);
57 } else {
58 (out->data + offset + sps_pps_size)[0] =
59 (out->data + offset + sps_pps_size)[1] = 0;
60 (out->data + offset + sps_pps_size)[2] = 1;
61 }
62
63 return 0;
64}
65
66static int h264_extradata_to_annexb(AVBSFContext *ctx, const int padding)
67{
68 H264BSFContext *s = ctx->priv_data;
69 uint16_t unit_size;
70 uint64_t total_size = 0;
71 uint8_t *out = NULL, unit_nb, sps_done = 0,
72 sps_seen = 0, pps_seen = 0;
73 const uint8_t *extradata = ctx->par_in->extradata + 4;
74 static const uint8_t nalu_header[4] = { 0, 0, 0, 1 };
75 int length_size = (*extradata++ & 0x3) + 1; // retrieve length coded size
76
77 s->sps_offset = s->pps_offset = -1;
78
79 /* retrieve sps and pps unit(s) */
80 unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
81 if (!unit_nb) {
82 goto pps;
83 } else {
84 s->sps_offset = 0;
85 sps_seen = 1;
86 }
87
88 while (unit_nb--) {
89 int err;
90
91 unit_size = AV_RB16(extradata);
92 total_size += unit_size + 4;
93 if (total_size > INT_MAX - padding) {
94 av_log(ctx, AV_LOG_ERROR,
95 "Too big extradata size, corrupted stream or invalid MP4/AVCC bitstream\n");
96 av_free(out);
97 return AVERROR(EINVAL);
98 }
99 if (extradata + 2 + unit_size > ctx->par_in->extradata + ctx->par_in->extradata_size) {
100 av_log(ctx, AV_LOG_ERROR, "Packet header is not contained in global extradata, "
101 "corrupted stream or invalid MP4/AVCC bitstream\n");
102 av_free(out);
103 return AVERROR(EINVAL);
104 }
105 if ((err = av_reallocp(&out, total_size + padding)) < 0)
106 return err;
107 memcpy(out + total_size - unit_size - 4, nalu_header, 4);
108 memcpy(out + total_size - unit_size, extradata + 2, unit_size);
109 extradata += 2 + unit_size;
110pps:
111 if (!unit_nb && !sps_done++) {
112 unit_nb = *extradata++; /* number of pps unit(s) */
113 if (unit_nb) {
114 s->pps_offset = total_size;
115 pps_seen = 1;
116 }
117 }
118 }
119
120 if (out)
121 memset(out + total_size, 0, padding);
122
123 if (!sps_seen)
124 av_log(ctx, AV_LOG_WARNING,
125 "Warning: SPS NALU missing or invalid. "
126 "The resulting stream may not play.\n");
127
128 if (!pps_seen)
129 av_log(ctx, AV_LOG_WARNING,
130 "Warning: PPS NALU missing or invalid. "
131 "The resulting stream may not play.\n");
132
133 av_freep(&ctx->par_out->extradata);
134 ctx->par_out->extradata = out;
135 ctx->par_out->extradata_size = total_size;
136
137 return length_size;
138}
139
140static int h264_mp4toannexb_init(AVBSFContext *ctx)
141{
142 H264BSFContext *s = ctx->priv_data;
143 int extra_size = ctx->par_in->extradata_size;
144 int ret;
145
146 /* retrieve sps and pps NAL units from extradata */
147 if (!extra_size ||
148 (extra_size >= 3 && AV_RB24(ctx->par_in->extradata) == 1) ||
149 (extra_size >= 4 && AV_RB32(ctx->par_in->extradata) == 1)) {
150 av_log(ctx, AV_LOG_VERBOSE,
151 "The input looks like it is Annex B already\n");
152 } else if (extra_size >= 6) {
153 ret = h264_extradata_to_annexb(ctx, AV_INPUT_BUFFER_PADDING_SIZE);
154 if (ret < 0)
155 return ret;
156
157 s->length_size = ret;
158 s->new_idr = 1;
159 s->idr_sps_seen = 0;
160 s->idr_pps_seen = 0;
161 s->extradata_parsed = 1;
162 } else {
163 av_log(ctx, AV_LOG_ERROR, "Invalid extradata size: %d\n", extra_size);
164 return AVERROR_INVALIDDATA;
165 }
166
167 return 0;
168}
169
170static int h264_mp4toannexb_filter(AVBSFContext *ctx, AVPacket *out)
171{
172 H264BSFContext *s = ctx->priv_data;
173
174 AVPacket *in;
175 uint8_t unit_type;
176 int32_t nal_size;
177 uint32_t cumul_size = 0;
178 const uint8_t *buf;
179 const uint8_t *buf_end;
180 int buf_size;
181 int ret = 0, i;
182
183 ret = ff_bsf_get_packet(ctx, &in);
184 if (ret < 0)
185 return ret;
186
187 /* nothing to filter */
188 if (!s->extradata_parsed) {
189 av_packet_move_ref(out, in);
190 av_packet_free(&in);
191 return 0;
192 }
193
194 buf = in->data;
195 buf_size = in->size;
196 buf_end = in->data + in->size;
197
198 do {
199 ret= AVERROR(EINVAL);
200 if (buf + s->length_size > buf_end)
201 goto fail;
202
203 for (nal_size = 0, i = 0; i<s->length_size; i++)
204 nal_size = (nal_size << 8) | buf[i];
205
206 buf += s->length_size;
207 unit_type = *buf & 0x1f;
208
209 if (nal_size > buf_end - buf || nal_size < 0)
210 goto fail;
211
212 if (unit_type == 7)
213 s->idr_sps_seen = s->new_idr = 1;
214 else if (unit_type == 8) {
215 s->idr_pps_seen = s->new_idr = 1;
216 /* if SPS has not been seen yet, prepend the AVCC one to PPS */
217 if (!s->idr_sps_seen) {
218 if (s->sps_offset == -1)
219 av_log(ctx, AV_LOG_WARNING, "SPS not present in the stream, nor in AVCC, stream may be unreadable\n");
220 else {
221 if ((ret = alloc_and_copy(out,
222 ctx->par_out->extradata + s->sps_offset,
223 s->pps_offset != -1 ? s->pps_offset : ctx->par_out->extradata_size - s->sps_offset,
224 buf, nal_size)) < 0)
225 goto fail;
226 s->idr_sps_seen = 1;
227 goto next_nal;
228 }
229 }
230 }
231
232 /* if this is a new IDR picture following an IDR picture, reset the idr flag.
233 * Just check first_mb_in_slice to be 0 as this is the simplest solution.
234 * This could be checking idr_pic_id instead, but would complexify the parsing. */
235 if (!s->new_idr && unit_type == 5 && (buf[1] & 0x80))
236 s->new_idr = 1;
237
238 /* prepend only to the first type 5 NAL unit of an IDR picture, if no sps/pps are already present */
239 if (s->new_idr && unit_type == 5 && !s->idr_sps_seen && !s->idr_pps_seen) {
240 if ((ret=alloc_and_copy(out,
241 ctx->par_out->extradata, ctx->par_out->extradata_size,
242 buf, nal_size)) < 0)
243 goto fail;
244 s->new_idr = 0;
245 /* if only SPS has been seen, also insert PPS */
246 } else if (s->new_idr && unit_type == 5 && s->idr_sps_seen && !s->idr_pps_seen) {
247 if (s->pps_offset == -1) {
248 av_log(ctx, AV_LOG_WARNING, "PPS not present in the stream, nor in AVCC, stream may be unreadable\n");
249 if ((ret = alloc_and_copy(out, NULL, 0, buf, nal_size)) < 0)
250 goto fail;
251 } else if ((ret = alloc_and_copy(out,
252 ctx->par_out->extradata + s->pps_offset, ctx->par_out->extradata_size - s->pps_offset,
253 buf, nal_size)) < 0)
254 goto fail;
255 } else {
256 if ((ret=alloc_and_copy(out, NULL, 0, buf, nal_size)) < 0)
257 goto fail;
258 if (!s->new_idr && unit_type == 1) {
259 s->new_idr = 1;
260 s->idr_sps_seen = 0;
261 s->idr_pps_seen = 0;
262 }
263 }
264
265next_nal:
266 buf += nal_size;
267 cumul_size += nal_size + s->length_size;
268 } while (cumul_size < buf_size);
269
270 ret = av_packet_copy_props(out, in);
271 if (ret < 0)
272 goto fail;
273
274fail:
275 if (ret < 0)
276 av_packet_unref(out);
277 av_packet_free(&in);
278
279 return ret;
280}
281
282static const enum AVCodecID codec_ids[] = {
283 AV_CODEC_ID_H264, AV_CODEC_ID_NONE,
284};
285
286const AVBitStreamFilter ff_h264_mp4toannexb_bsf = {
287 .name = "h264_mp4toannexb",
288 .priv_data_size = sizeof(H264BSFContext),
289 .init = h264_mp4toannexb_init,
290 .filter = h264_mp4toannexb_filter,
291 .codec_ids = codec_ids,
292};
293
generated by cgit at 2024-05-17 05:12:42 (GMT)