936418a8a02ae6483e9203c73c19dd22ae359e70
[libav.git] / libavcodec / h264_mp4toannexb_bsf.c
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 "libavutil/intreadwrite.h"
23 #include "avcodec.h"
24
25 typedef struct H264BSFContext {
26 uint8_t length_size;
27 uint8_t first_idr;
28 uint8_t *sps_pps_data;
29 uint32_t size;
30 } H264BSFContext;
31
32 static void alloc_and_copy(uint8_t **poutbuf, int *poutbuf_size,
33 const uint8_t *sps_pps, uint32_t sps_pps_size,
34 const uint8_t *in, uint32_t in_size) {
35 uint32_t offset = *poutbuf_size;
36 uint8_t nal_header_size = offset ? 3 : 4;
37
38 *poutbuf_size += sps_pps_size+in_size+nal_header_size;
39 *poutbuf = av_realloc(*poutbuf, *poutbuf_size);
40 if (sps_pps)
41 memcpy(*poutbuf+offset, sps_pps, sps_pps_size);
42 memcpy(*poutbuf+sps_pps_size+nal_header_size+offset, in, in_size);
43 if (!offset)
44 AV_WB32(*poutbuf+sps_pps_size, 1);
45 else {
46 (*poutbuf+offset+sps_pps_size)[0] = (*poutbuf+offset+sps_pps_size)[1] = 0;
47 (*poutbuf+offset+sps_pps_size)[2] = 1;
48 }
49 }
50
51 static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
52 AVCodecContext *avctx, const char *args,
53 uint8_t **poutbuf, int *poutbuf_size,
54 const uint8_t *buf, int buf_size,
55 int keyframe) {
56 H264BSFContext *ctx = bsfc->priv_data;
57 uint8_t unit_type;
58 uint32_t nal_size, cumul_size = 0;
59
60 /* nothing to filter */
61 if (!avctx->extradata || avctx->extradata_size < 6) {
62 *poutbuf = (uint8_t*) buf;
63 *poutbuf_size = buf_size;
64 return 0;
65 }
66
67 /* retrieve sps and pps NAL units from extradata */
68 if (!ctx->sps_pps_data) {
69 uint16_t unit_size;
70 uint32_t total_size = 0;
71 uint8_t *out = NULL, unit_nb, sps_done = 0;
72 const uint8_t *extradata = avctx->extradata+4;
73 static const uint8_t nalu_header[4] = {0, 0, 0, 1};
74
75 /* retrieve length coded size */
76 ctx->length_size = (*extradata++ & 0x3) + 1;
77 if (ctx->length_size == 3)
78 return AVERROR(EINVAL);
79
80 /* retrieve sps and pps unit(s) */
81 unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
82 if (!unit_nb) {
83 unit_nb = *extradata++; /* number of pps unit(s) */
84 sps_done++;
85 }
86 while (unit_nb--) {
87 unit_size = AV_RB16(extradata);
88 total_size += unit_size+4;
89 if (extradata+2+unit_size > avctx->extradata+avctx->extradata_size) {
90 av_free(out);
91 return AVERROR(EINVAL);
92 }
93 out = av_realloc(out, total_size);
94 if (!out)
95 return AVERROR(ENOMEM);
96 memcpy(out+total_size-unit_size-4, nalu_header, 4);
97 memcpy(out+total_size-unit_size, extradata+2, unit_size);
98 extradata += 2+unit_size;
99
100 if (!unit_nb && !sps_done++)
101 unit_nb = *extradata++; /* number of pps unit(s) */
102 }
103
104 ctx->sps_pps_data = out;
105 ctx->size = total_size;
106 ctx->first_idr = 1;
107 }
108
109 *poutbuf_size = 0;
110 *poutbuf = NULL;
111 do {
112 if (ctx->length_size == 1)
113 nal_size = buf[0];
114 else if (ctx->length_size == 2)
115 nal_size = AV_RB16(buf);
116 else
117 nal_size = AV_RB32(buf);
118
119 buf += ctx->length_size;
120 unit_type = *buf & 0x1f;
121
122 /* prepend only to the first type 5 NAL unit of an IDR picture */
123 if (ctx->first_idr && unit_type == 5) {
124 alloc_and_copy(poutbuf, poutbuf_size,
125 ctx->sps_pps_data, ctx->size,
126 buf, nal_size);
127 ctx->first_idr = 0;
128 }
129 else {
130 alloc_and_copy(poutbuf, poutbuf_size,
131 NULL, 0,
132 buf, nal_size);
133 if (!ctx->first_idr && unit_type == 1)
134 ctx->first_idr = 1;
135 }
136
137 buf += nal_size;
138 cumul_size += nal_size + ctx->length_size;
139 } while (cumul_size < buf_size);
140
141 return 1;
142 }
143
144 static void h264_mp4toannexb_close(AVBitStreamFilterContext *bsfc)
145 {
146 H264BSFContext *ctx = bsfc->priv_data;
147 av_freep(&ctx->sps_pps_data);
148 }
149
150 AVBitStreamFilter h264_mp4toannexb_bsf = {
151 "h264_mp4toannexb",
152 sizeof(H264BSFContext),
153 h264_mp4toannexb_filter,
154 h264_mp4toannexb_close,
155 };
156