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
25typedef 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
32static 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
51static 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    int32_t nal_size;
59    uint32_t cumul_size = 0;
60    const uint8_t *buf_end = buf + buf_size;
61
62    /* nothing to filter */
63    if (!avctx->extradata || avctx->extradata_size < 6) {
64        *poutbuf = (uint8_t*) buf;
65        *poutbuf_size = buf_size;
66        return 0;
67    }
68
69    /* retrieve sps and pps NAL units from extradata */
70    if (!ctx->sps_pps_data) {
71        uint16_t unit_size;
72        uint32_t total_size = 0;
73        uint8_t *out = NULL, unit_nb, sps_done = 0;
74        const uint8_t *extradata = avctx->extradata+4;
75        static const uint8_t nalu_header[4] = {0, 0, 0, 1};
76
77        /* retrieve length coded size */
78        ctx->length_size = (*extradata++ & 0x3) + 1;
79        if (ctx->length_size == 3)
80            return AVERROR(EINVAL);
81
82        /* retrieve sps and pps unit(s) */
83        unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
84        if (!unit_nb) {
85            unit_nb = *extradata++; /* number of pps unit(s) */
86            sps_done++;
87        }
88        while (unit_nb--) {
89            unit_size = AV_RB16(extradata);
90            total_size += unit_size+4;
91            if (extradata+2+unit_size > avctx->extradata+avctx->extradata_size) {
92                av_free(out);
93                return AVERROR(EINVAL);
94            }
95            out = av_realloc(out, total_size);
96            if (!out)
97                return AVERROR(ENOMEM);
98            memcpy(out+total_size-unit_size-4, nalu_header, 4);
99            memcpy(out+total_size-unit_size,   extradata+2, unit_size);
100            extradata += 2+unit_size;
101
102            if (!unit_nb && !sps_done++)
103                unit_nb = *extradata++; /* number of pps unit(s) */
104        }
105
106        ctx->sps_pps_data = out;
107        ctx->size = total_size;
108        ctx->first_idr = 1;
109    }
110
111    *poutbuf_size = 0;
112    *poutbuf = NULL;
113    do {
114        if (buf + ctx->length_size > buf_end)
115            goto fail;
116
117        if (ctx->length_size == 1)
118            nal_size = buf[0];
119        else if (ctx->length_size == 2)
120            nal_size = AV_RB16(buf);
121        else
122            nal_size = AV_RB32(buf);
123
124        buf += ctx->length_size;
125        unit_type = *buf & 0x1f;
126
127        if (buf + nal_size > buf_end || nal_size < 0)
128            goto fail;
129
130        /* prepend only to the first type 5 NAL unit of an IDR picture */
131        if (ctx->first_idr && unit_type == 5) {
132            alloc_and_copy(poutbuf, poutbuf_size,
133                           ctx->sps_pps_data, ctx->size,
134                           buf, nal_size);
135            ctx->first_idr = 0;
136        }
137        else {
138            alloc_and_copy(poutbuf, poutbuf_size,
139                           NULL, 0,
140                           buf, nal_size);
141            if (!ctx->first_idr && unit_type == 1)
142                ctx->first_idr = 1;
143        }
144
145        buf += nal_size;
146        cumul_size += nal_size + ctx->length_size;
147    } while (cumul_size < buf_size);
148
149    return 1;
150
151fail:
152    av_freep(poutbuf);
153    *poutbuf_size = 0;
154    return AVERROR(EINVAL);
155}
156
157static void h264_mp4toannexb_close(AVBitStreamFilterContext *bsfc)
158{
159    H264BSFContext *ctx = bsfc->priv_data;
160    av_freep(&ctx->sps_pps_data);
161}
162
163AVBitStreamFilter h264_mp4toannexb_bsf = {
164    "h264_mp4toannexb",
165    sizeof(H264BSFContext),
166    h264_mp4toannexb_filter,
167    h264_mp4toannexb_close,
168};
169
170