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     int      extradata_parsed;
  29 } H264BSFContext;
  30
  31 static int alloc_and_copy(uint8_t **poutbuf,          int *poutbuf_size,
  32                           const uint8_t *sps_pps, uint32_t sps_pps_size,
  33                           const uint8_t *in,      uint32_t in_size) {
  34     uint32_t offset = *poutbuf_size;
  35     uint8_t nal_header_size = offset ? 3 : 4;
  36     void *tmp;
  37
  38     *poutbuf_size += sps_pps_size+in_size+nal_header_size;
  39     tmp = av_realloc(*poutbuf, *poutbuf_size);
  40     if (!tmp)
  41         return AVERROR(ENOMEM);
  42     *poutbuf = tmp;
  43     if (sps_pps)
  44         memcpy(*poutbuf+offset, sps_pps, sps_pps_size);
  45     memcpy(*poutbuf+sps_pps_size+nal_header_size+offset, in, in_size);
  46     if (!offset) {
  47         AV_WB32(*poutbuf+sps_pps_size, 1);
  48     } else {
  49         (*poutbuf+offset+sps_pps_size)[0] = (*poutbuf+offset+sps_pps_size)[1] = 0;
  50         (*poutbuf+offset+sps_pps_size)[2] = 1;
  51     }
  52
  53     return 0;
  54 }
  55
  56 static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
  57                                    AVCodecContext *avctx, const char *args,
  58                                    uint8_t  **poutbuf, int *poutbuf_size,
  59                                    const uint8_t *buf, int      buf_size,
  60                                    int keyframe) {
  61     H264BSFContext *ctx = bsfc->priv_data;
  62     uint8_t unit_type;
  63     int32_t nal_size;
  64     uint32_t cumul_size = 0;
  65     const uint8_t *buf_end = buf + buf_size;
  66
  67     /* nothing to filter */
  68     if (!avctx->extradata || avctx->extradata_size < 6) {
  69         *poutbuf = (uint8_t*) buf;
  70         *poutbuf_size = buf_size;
  71         return 0;
  72     }
  73
  74     /* retrieve sps and pps NAL units from extradata */
  75     if (!ctx->extradata_parsed) {
  76         uint16_t unit_size;
  77         uint64_t total_size = 0;
  78         uint8_t *out = NULL, unit_nb, sps_done = 0;
  79         const uint8_t *extradata = avctx->extradata+4;
  80         static const uint8_t nalu_header[4] = {0, 0, 0, 1};
  81
  82         /* retrieve length coded size */
  83         ctx->length_size = (*extradata++ & 0x3) + 1;
  84         if (ctx->length_size == 3)
  85             return AVERROR(EINVAL);
  86
  87         /* retrieve sps and pps unit(s) */
  88         unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
  89         if (!unit_nb) {
  90             unit_nb = *extradata++; /* number of pps unit(s) */
  91             sps_done++;
  92         }
  93         while (unit_nb--) {
  94             void *tmp;
  95
  96             unit_size = AV_RB16(extradata);
  97             total_size += unit_size+4;
  98             if (total_size > INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE ||
  99                 extradata+2+unit_size > avctx->extradata+avctx->extradata_size) {
 100                 av_free(out);
 101                 return AVERROR(EINVAL);
 102             }
 103             tmp = av_realloc(out, total_size + FF_INPUT_BUFFER_PADDING_SIZE);
 104             if (!tmp) {
 105                 av_free(out);
 106                 return AVERROR(ENOMEM);
 107             }
 108             out = tmp;
 109             memcpy(out+total_size-unit_size-4, nalu_header, 4);
 110             memcpy(out+total_size-unit_size,   extradata+2, unit_size);
 111             extradata += 2+unit_size;
 112
 113             if (!unit_nb && !sps_done++)
 114                 unit_nb = *extradata++; /* number of pps unit(s) */
 115         }
 116
 117         memset(out + total_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
 118         av_free(avctx->extradata);
 119         avctx->extradata      = out;
 120         avctx->extradata_size = total_size;
 121         ctx->first_idr        = 1;
 122         ctx->extradata_parsed = 1;
 123     }
 124
 125     *poutbuf_size = 0;
 126     *poutbuf = NULL;
 127     do {
 128         if (buf + ctx->length_size > buf_end)
 129             goto fail;
 130
 131         if (ctx->length_size == 1) {
 132             nal_size = buf[0];
 133         } else if (ctx->length_size == 2) {
 134             nal_size = AV_RB16(buf);
 135         } else
 136             nal_size = AV_RB32(buf);
 137
 138         buf += ctx->length_size;
 139         unit_type = *buf & 0x1f;
 140
 141         if (buf + nal_size > buf_end || nal_size < 0)
 142             goto fail;
 143
 144         /* prepend only to the first type 5 NAL unit of an IDR picture */
 145         if (ctx->first_idr && unit_type == 5) {
 146             if (alloc_and_copy(poutbuf, poutbuf_size,
 147                                avctx->extradata, avctx->extradata_size,
 148                                buf, nal_size) < 0)
 149                 goto fail;
 150             ctx->first_idr = 0;
 151         } else {
 152             if (alloc_and_copy(poutbuf, poutbuf_size,
 153                                NULL, 0,
 154                                buf, nal_size) < 0)
 155                 goto fail;
 156             if (!ctx->first_idr && unit_type == 1)
 157                 ctx->first_idr = 1;
 158         }
 159
 160         buf += nal_size;
 161         cumul_size += nal_size + ctx->length_size;
 162     } while (cumul_size < buf_size);
 163
 164     return 1;
 165
 166 fail:
 167     av_freep(poutbuf);
 168     *poutbuf_size = 0;
 169     return AVERROR(EINVAL);
 170 }
 171
 172 AVBitStreamFilter ff_h264_mp4toannexb_bsf = {
 173     "h264_mp4toannexb",
 174     sizeof(H264BSFContext),
 175     h264_mp4toannexb_filter,
 176 };
 177