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