Add a bitstream filter for H.264.
[libav.git] / libavcodec / h264_mp4toannexb_bsf.c
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1/*
2 * Copyright (c) 2007 Benoit Fouet <benoit.fouet@purplelabs.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#include "avcodec.h"
22
23typedef struct H264BSFContext {
24 uint8_t length_size;
25 uint8_t first_idr;
26 uint8_t *sps_pps_data;
27 uint32_t size;
28} H264BSFContext;
29
30static void alloc_and_copy(uint8_t **poutbuf, int *poutbuf_size,
31 const uint8_t *sps_pps, uint32_t sps_pps_size,
32 const uint8_t *in, uint32_t in_size) {
33 uint32_t offset = *poutbuf_size;
34 uint8_t nal_header_size = offset ? 3 : 4;
35
36 *poutbuf_size += sps_pps_size+in_size+nal_header_size;
37 *poutbuf = av_realloc(*poutbuf, *poutbuf_size);
38 if (sps_pps)
39 memcpy(*poutbuf+offset, sps_pps, sps_pps_size);
40 memcpy(*poutbuf+sps_pps_size+nal_header_size+offset, in, in_size);
41 if (!offset)
42 AV_WB32(*poutbuf+sps_pps_size, 1);
43 else {
44 (*poutbuf+offset)[0] = (*poutbuf+offset)[1] = 0;
45 (*poutbuf+offset)[2] = 1;
46 }
47}
48
49static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
50 AVCodecContext *avctx, const char *args,
51 uint8_t **poutbuf, int *poutbuf_size,
52 const uint8_t *buf, int buf_size,
53 int keyframe) {
54 H264BSFContext *ctx = bsfc->priv_data;
55 uint8_t unit_type;
56 uint32_t nal_size, cumul_size = 0;
57
58 /* nothing to filter */
59 if (!avctx->extradata || avctx->extradata_size < 6) {
60 *poutbuf = (uint8_t*) buf;
61 *poutbuf_size = buf_size;
62 return 0;
63 }
64
65 /* retrieve sps and pps NAL units from extradata */
66 if (!ctx->sps_pps_data) {
67 uint16_t unit_size;
68 uint32_t total_size = 0;
69 uint8_t *out = NULL, unit_nb, sps_done = 0;
70 const uint8_t *extradata = avctx->extradata+4;
71 static const uint8_t nalu_header[4] = {0, 0, 0, 1};
72
73 /* retrieve length coded size */
74 ctx->length_size = (*extradata++ & 0x3) + 1;
75 if (ctx->length_size == 3)
76 return AVERROR(EINVAL);
77
78 /* retrieve sps and pps unit(s) */
79 unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
80 if (!unit_nb) {
81 unit_nb = *extradata++; /* number of pps unit(s) */
82 sps_done++;
83 }
84 while (unit_nb--) {
85 unit_size = AV_RB16(extradata);
86 total_size += unit_size+4;
87 if (extradata+2+unit_size > avctx->extradata+avctx->extradata_size) {
88 av_free(out);
89 return AVERROR(EINVAL);
90 }
91 out = av_realloc(out, total_size);
92 if (!out)
93 return AVERROR(ENOMEM);
94 memcpy(out+total_size-unit_size-4, nalu_header, 4);
95 memcpy(out+total_size-unit_size, extradata+2, unit_size);
96 extradata += 2+unit_size;
97
98 if (!unit_nb && !sps_done++)
99 unit_nb = *extradata++; /* number of pps unit(s) */
100 }
101
102 ctx->sps_pps_data = out;
103 ctx->size = total_size;
104 ctx->first_idr = 1;
105 }
106
107 *poutbuf_size = 0;
108 *poutbuf = NULL;
109 do {
110 if (ctx->length_size == 1)
111 nal_size = buf[0];
112 else if (ctx->length_size == 2)
113 nal_size = AV_RB16(buf);
114 else
115 nal_size = AV_RB32(buf);
116
117 buf += ctx->length_size;
118 unit_type = *buf & 0x1f;
119
120 /* prepend only to the first type 5 NAL unit of an IDR picture */
121 if (ctx->first_idr && unit_type == 5) {
122 alloc_and_copy(poutbuf, poutbuf_size,
123 ctx->sps_pps_data, ctx->size,
124 buf, nal_size);
125 ctx->first_idr = 0;
126 }
127 else {
128 alloc_and_copy(poutbuf, poutbuf_size,
129 NULL, 0,
130 buf, nal_size);
131 if (!ctx->first_idr && unit_type == 1)
132 ctx->first_idr = 1;
133 }
134
135 buf += nal_size;
136 cumul_size += nal_size + ctx->length_size;
137 } while (cumul_size < buf_size);
138
139 return 1;
140}
141
142static void h264_mp4toannexb_close(AVBitStreamFilterContext *bsfc)
143{
144 H264BSFContext *ctx = bsfc->priv_data;
145 av_freep(&ctx->sps_pps_data);
146}
147
148AVBitStreamFilter h264_mp4toannexb_bsf = {
149 "h264_mp4toannexb",
150 sizeof(H264BSFContext),
151 h264_mp4toannexb_filter,
152 h264_mp4toannexb_close,
153};
154