libavcodec/h264_mp4toannexb_bsf.c

   1 /*
   2  * Copyright (c) 2007 Benoit Fouet <benoit.fouet@free.fr>
   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 "libavutil/intreadwrite.h"
  22 #include "avcodec.h"
  23
  24 typedef struct H264BSFContext {
  25     uint8_t  length_size;
  26     uint8_t  first_idr;
  27     uint8_t *sps_pps_data;
  28     uint32_t size;
  29 } H264BSFContext;
  30
  31 static void 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
  37     *poutbuf_size += sps_pps_size+in_size+nal_header_size;
  38     *poutbuf = av_realloc(*poutbuf, *poutbuf_size);
  39     if (sps_pps)
  40         memcpy(*poutbuf+offset, sps_pps, sps_pps_size);
  41     memcpy(*poutbuf+sps_pps_size+nal_header_size+offset, in, in_size);
  42     if (!offset)
  43         AV_WB32(*poutbuf+sps_pps_size, 1);
  44     else {
  45         (*poutbuf+offset+sps_pps_size)[0] = (*poutbuf+offset+sps_pps_size)[1] = 0;
  46         (*poutbuf+offset+sps_pps_size)[2] = 1;
  47     }
  48 }
  49
  50 static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
  51                                    AVCodecContext *avctx, const char *args,
  52                                    uint8_t  **poutbuf, int *poutbuf_size,
  53                                    const uint8_t *buf, int      buf_size,
  54                                    int keyframe) {
  55     H264BSFContext *ctx = bsfc->priv_data;
  56     uint8_t unit_type;
  57     uint32_t nal_size, cumul_size = 0;
  58
  59     /* nothing to filter */
  60     if (!avctx->extradata || avctx->extradata_size < 6) {
  61         *poutbuf = (uint8_t*) buf;
  62         *poutbuf_size = buf_size;
  63         return 0;
  64     }
  65
  66     /* retrieve sps and pps NAL units from extradata */
  67     if (!ctx->sps_pps_data) {
  68         uint16_t unit_size;
  69         uint32_t total_size = 0;
  70         uint8_t *out = NULL, unit_nb, sps_done = 0;
  71         const uint8_t *extradata = avctx->extradata+4;
  72         static const uint8_t nalu_header[4] = {0, 0, 0, 1};
  73
  74         /* retrieve length coded size */
  75         ctx->length_size = (*extradata++ & 0x3) + 1;
  76         if (ctx->length_size == 3)
  77             return AVERROR(EINVAL);
  78
  79         /* retrieve sps and pps unit(s) */
  80         unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
  81         if (!unit_nb) {
  82             unit_nb = *extradata++; /* number of pps unit(s) */
  83             sps_done++;
  84         }
  85         while (unit_nb--) {
  86             unit_size = AV_RB16(extradata);
  87             total_size += unit_size+4;
  88             if (extradata+2+unit_size > avctx->extradata+avctx->extradata_size) {
  89                 av_free(out);
  90                 return AVERROR(EINVAL);
  91             }
  92             out = av_realloc(out, total_size);
  93             if (!out)
  94                 return AVERROR(ENOMEM);
  95             memcpy(out+total_size-unit_size-4, nalu_header, 4);
  96             memcpy(out+total_size-unit_size,   extradata+2, unit_size);
  97             extradata += 2+unit_size;
  98
  99             if (!unit_nb && !sps_done++)
 100                 unit_nb = *extradata++; /* number of pps unit(s) */
 101         }
 102
 103         ctx->sps_pps_data = out;
 104         ctx->size = total_size;
 105         ctx->first_idr = 1;
 106     }
 107
 108     *poutbuf_size = 0;
 109     *poutbuf = NULL;
 110     do {
 111         if (ctx->length_size == 1)
 112             nal_size = buf[0];
 113         else if (ctx->length_size == 2)
 114             nal_size = AV_RB16(buf);
 115         else
 116             nal_size = AV_RB32(buf);
 117
 118         buf += ctx->length_size;
 119         unit_type = *buf & 0x1f;
 120
 121         /* prepend only to the first type 5 NAL unit of an IDR picture */
 122         if (ctx->first_idr && unit_type == 5) {
 123             alloc_and_copy(poutbuf, poutbuf_size,
 124                            ctx->sps_pps_data, ctx->size,
 125                            buf, nal_size);
 126             ctx->first_idr = 0;
 127         }
 128         else {
 129             alloc_and_copy(poutbuf, poutbuf_size,
 130                            NULL, 0,
 131                            buf, nal_size);
 132             if (!ctx->first_idr && unit_type == 1)
 133                 ctx->first_idr = 1;
 134         }
 135
 136         buf += nal_size;
 137         cumul_size += nal_size + ctx->length_size;
 138     } while (cumul_size < buf_size);
 139
 140     return 1;
 141 }
 142
 143 static void h264_mp4toannexb_close(AVBitStreamFilterContext *bsfc)
 144 {
 145     H264BSFContext *ctx = bsfc->priv_data;
 146     av_freep(&ctx->sps_pps_data);
 147 }
 148
 149 AVBitStreamFilter h264_mp4toannexb_bsf = {
 150     "h264_mp4toannexb",
 151     sizeof(H264BSFContext),
 152     h264_mp4toannexb_filter,
 153     h264_mp4toannexb_close,
 154 };
 155