libavcodec/h264_mp4toannexb_bsf.c

   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
  23 typedef 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
  30 static 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+sps_pps_size)[0] = (*poutbuf+offset+sps_pps_size)[1] = 0;
  45         (*poutbuf+offset+sps_pps_size)[2] = 1;
  46     }
  47 }
  48
  49 static 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
 142 static void h264_mp4toannexb_close(AVBitStreamFilterContext *bsfc)
 143 {
 144     H264BSFContext *ctx = bsfc->priv_data;
 145     av_freep(&ctx->sps_pps_data);
 146 }
 147
 148 AVBitStreamFilter h264_mp4toannexb_bsf = {
 149     "h264_mp4toannexb",
 150     sizeof(H264BSFContext),
 151     h264_mp4toannexb_filter,
 152     h264_mp4toannexb_close,
 153 };
 154