2 * H.264 MP4 to Annex B byte stream format filter
3 * Copyright (c) 2007 Benoit Fouet <benoit.fouet@free.fr>
5 * This file is part of FFmpeg.
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.
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.
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
24 #include "libavutil/avassert.h"
25 #include "libavutil/intreadwrite.h"
26 #include "libavutil/mem.h"
30 #include "bytestream.h"
33 typedef struct H264BSFContext {
45 static void count_or_copy(uint8_t **out, uint64_t *out_size,
46 const uint8_t *in, int in_size, int ps, int copy)
48 uint8_t start_code_size = ps < 0 ? 0 : *out_size == 0 || ps ? 4 : 3;
51 memcpy(*out + start_code_size, in, in_size);
52 if (start_code_size == 4) {
54 } else if (start_code_size) {
59 *out += start_code_size + in_size;
61 *out_size += start_code_size + in_size;
64 static int h264_extradata_to_annexb(AVBSFContext *ctx, const int padding)
66 H264BSFContext *s = ctx->priv_data;
67 GetByteContext ogb, *gb = &ogb;
69 uint32_t total_size = 0;
70 uint8_t *out = NULL, unit_nb, sps_done = 0;
71 static const uint8_t nalu_header[4] = { 0, 0, 0, 1 };
72 int length_size, pps_offset = 0;
74 bytestream2_init(gb, ctx->par_in->extradata, ctx->par_in->extradata_size);
76 bytestream2_skipu(gb, 4);
78 /* retrieve length coded size */
79 length_size = (bytestream2_get_byteu(gb) & 0x3) + 1;
81 /* retrieve sps and pps unit(s) */
82 unit_nb = bytestream2_get_byteu(gb) & 0x1f; /* number of sps unit(s) */
90 /* possible overread ok due to padding */
91 unit_size = bytestream2_get_be16u(gb);
92 total_size += unit_size + 4;
93 av_assert1(total_size <= INT_MAX - padding);
94 if (bytestream2_get_bytes_left(gb) < unit_size + !sps_done) {
95 av_log(ctx, AV_LOG_ERROR, "Global extradata truncated, "
96 "corrupted stream or invalid MP4/AVCC bitstream\n");
98 return AVERROR_INVALIDDATA;
100 if ((err = av_reallocp(&out, total_size + padding)) < 0)
102 memcpy(out + total_size - unit_size - 4, nalu_header, 4);
103 bytestream2_get_bufferu(gb, out + total_size - unit_size, unit_size);
105 if (!unit_nb && !sps_done++) {
106 unit_nb = bytestream2_get_byteu(gb); /* number of pps unit(s) */
107 pps_offset = total_size;
112 memset(out + total_size, 0, padding);
116 s->sps_size = pps_offset;
118 av_log(ctx, AV_LOG_WARNING,
119 "Warning: SPS NALU missing or invalid. "
120 "The resulting stream may not play.\n");
122 if (pps_offset < total_size) {
123 s->pps = out + pps_offset;
124 s->pps_size = total_size - pps_offset;
126 av_log(ctx, AV_LOG_WARNING,
127 "Warning: PPS NALU missing or invalid. "
128 "The resulting stream may not play.\n");
131 av_freep(&ctx->par_out->extradata);
132 ctx->par_out->extradata = out;
133 ctx->par_out->extradata_size = total_size;
138 static int h264_mp4toannexb_init(AVBSFContext *ctx)
140 H264BSFContext *s = ctx->priv_data;
141 int extra_size = ctx->par_in->extradata_size;
144 /* retrieve sps and pps NAL units from extradata */
146 (extra_size >= 3 && AV_RB24(ctx->par_in->extradata) == 1) ||
147 (extra_size >= 4 && AV_RB32(ctx->par_in->extradata) == 1)) {
148 av_log(ctx, AV_LOG_VERBOSE,
149 "The input looks like it is Annex B already\n");
150 } else if (extra_size >= 7) {
151 ret = h264_extradata_to_annexb(ctx, AV_INPUT_BUFFER_PADDING_SIZE);
155 s->length_size = ret;
159 s->extradata_parsed = 1;
161 av_log(ctx, AV_LOG_ERROR, "Invalid extradata size: %d\n", extra_size);
162 return AVERROR_INVALIDDATA;
168 static int h264_mp4toannexb_filter(AVBSFContext *ctx, AVPacket *opkt)
170 H264BSFContext *s = ctx->priv_data;
172 uint8_t unit_type, new_idr, sps_seen, pps_seen;
174 const uint8_t *buf_end;
179 ret = ff_bsf_get_packet(ctx, &in);
183 /* nothing to filter */
184 if (!s->extradata_parsed) {
185 av_packet_move_ref(opkt, in);
190 buf_end = in->data + in->size;
192 #define LOG_ONCE(...) \
195 for (int j = 0; j < 2; j++) {
197 new_idr = s->new_idr;
198 sps_seen = s->idr_sps_seen;
199 pps_seen = s->idr_pps_seen;
203 uint32_t nal_size = 0;
205 /* possible overread ok due to padding */
206 for (int i = 0; i < s->length_size; i++)
207 nal_size = (nal_size << 8) | buf[i];
209 buf += s->length_size;
211 /* This check requires the cast as the right side might
212 * otherwise be promoted to an unsigned value. */
213 if ((int64_t)nal_size > buf_end - buf) {
214 ret = AVERROR_INVALIDDATA;
221 unit_type = *buf & 0x1f;
223 if (unit_type == H264_NAL_SPS) {
224 sps_seen = new_idr = 1;
225 } else if (unit_type == H264_NAL_PPS) {
226 pps_seen = new_idr = 1;
227 /* if SPS has not been seen yet, prepend the AVCC one to PPS */
230 LOG_ONCE(ctx, AV_LOG_WARNING, "SPS not present in the stream, nor in AVCC, stream may be unreadable\n");
232 count_or_copy(&out, &out_size, s->sps, s->sps_size, -1, j);
238 /* If this is a new IDR picture following an IDR picture, reset the idr flag.
239 * Just check first_mb_in_slice to be 0 as this is the simplest solution.
240 * This could be checking idr_pic_id instead, but would complexify the parsing. */
241 if (!new_idr && unit_type == H264_NAL_IDR_SLICE && (buf[1] & 0x80))
244 /* prepend only to the first type 5 NAL unit of an IDR picture, if no sps/pps are already present */
245 if (new_idr && unit_type == H264_NAL_IDR_SLICE && !sps_seen && !pps_seen) {
246 if (ctx->par_out->extradata)
247 count_or_copy(&out, &out_size, ctx->par_out->extradata,
248 ctx->par_out->extradata_size, -1, j);
250 /* if only SPS has been seen, also insert PPS */
251 } else if (new_idr && unit_type == H264_NAL_IDR_SLICE && sps_seen && !pps_seen) {
253 LOG_ONCE(ctx, AV_LOG_WARNING, "PPS not present in the stream, nor in AVCC, stream may be unreadable\n");
255 count_or_copy(&out, &out_size, s->pps, s->pps_size, -1, j);
259 count_or_copy(&out, &out_size, buf, nal_size,
260 unit_type == H264_NAL_SPS || unit_type == H264_NAL_PPS, j);
261 if (!new_idr && unit_type == H264_NAL_SLICE) {
268 } while (buf < buf_end);
271 if (out_size > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE) {
272 ret = AVERROR_INVALIDDATA;
275 ret = av_new_packet(opkt, out_size);
283 av_assert1(out_size == opkt->size);
285 s->new_idr = new_idr;
286 s->idr_sps_seen = sps_seen;
287 s->idr_pps_seen = pps_seen;
289 ret = av_packet_copy_props(opkt, in);
295 av_packet_unref(opkt);
301 static void h264_mp4toannexb_flush(AVBSFContext *ctx)
303 H264BSFContext *s = ctx->priv_data;
307 s->new_idr = s->extradata_parsed;
310 static const enum AVCodecID codec_ids[] = {
311 AV_CODEC_ID_H264, AV_CODEC_ID_NONE,
314 const AVBitStreamFilter ff_h264_mp4toannexb_bsf = {
315 .name = "h264_mp4toannexb",
316 .priv_data_size = sizeof(H264BSFContext),
317 .init = h264_mp4toannexb_init,
318 .filter = h264_mp4toannexb_filter,
319 .flush = h264_mp4toannexb_flush,
320 .codec_ids = codec_ids,