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  1. /*
  2.  * AVC helper functions for muxers
  3.  * Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>
  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 "avformat.h"
  24. #include "avio.h"
  25. #include "avc.h"
  26.  
  27. static const uint8_t *ff_avc_find_startcode_internal(const uint8_t *p, const uint8_t *end)
  28. {
  29.     const uint8_t *a = p + 4 - ((intptr_t)p & 3);
  30.  
  31.     for (end -= 3; p < a && p < end; p++) {
  32.         if (p[0] == 0 && p[1] == 0 && p[2] == 1)
  33.             return p;
  34.     }
  35.  
  36.     for (end -= 3; p < end; p += 4) {
  37.         uint32_t x = *(const uint32_t*)p;
  38. //      if ((x - 0x01000100) & (~x) & 0x80008000) // little endian
  39. //      if ((x - 0x00010001) & (~x) & 0x00800080) // big endian
  40.         if ((x - 0x01010101) & (~x) & 0x80808080) { // generic
  41.             if (p[1] == 0) {
  42.                 if (p[0] == 0 && p[2] == 1)
  43.                     return p;
  44.                 if (p[2] == 0 && p[3] == 1)
  45.                     return p+1;
  46.             }
  47.             if (p[3] == 0) {
  48.                 if (p[2] == 0 && p[4] == 1)
  49.                     return p+2;
  50.                 if (p[4] == 0 && p[5] == 1)
  51.                     return p+3;
  52.             }
  53.         }
  54.     }
  55.  
  56.     for (end += 3; p < end; p++) {
  57.         if (p[0] == 0 && p[1] == 0 && p[2] == 1)
  58.             return p;
  59.     }
  60.  
  61.     return end + 3;
  62. }
  63.  
  64. const uint8_t *ff_avc_find_startcode(const uint8_t *p, const uint8_t *end){
  65.     const uint8_t *out= ff_avc_find_startcode_internal(p, end);
  66.     if(p<out && out<end && !out[-1]) out--;
  67.     return out;
  68. }
  69.  
  70. int ff_avc_parse_nal_units(AVIOContext *pb, const uint8_t *buf_in, int size)
  71. {
  72.     const uint8_t *p = buf_in;
  73.     const uint8_t *end = p + size;
  74.     const uint8_t *nal_start, *nal_end;
  75.  
  76.     size = 0;
  77.     nal_start = ff_avc_find_startcode(p, end);
  78.     for (;;) {
  79.         while (nal_start < end && !*(nal_start++));
  80.         if (nal_start == end)
  81.             break;
  82.  
  83.         nal_end = ff_avc_find_startcode(nal_start, end);
  84.         avio_wb32(pb, nal_end - nal_start);
  85.         avio_write(pb, nal_start, nal_end - nal_start);
  86.         size += 4 + nal_end - nal_start;
  87.         nal_start = nal_end;
  88.     }
  89.     return size;
  90. }
  91.  
  92. int ff_avc_parse_nal_units_buf(const uint8_t *buf_in, uint8_t **buf, int *size)
  93. {
  94.     AVIOContext *pb;
  95.     int ret = avio_open_dyn_buf(&pb);
  96.     if(ret < 0)
  97.         return ret;
  98.  
  99.     ff_avc_parse_nal_units(pb, buf_in, *size);
  100.  
  101.     av_freep(buf);
  102.     *size = avio_close_dyn_buf(pb, buf);
  103.     return 0;
  104. }
  105.  
  106. int ff_isom_write_avcc(AVIOContext *pb, const uint8_t *data, int len)
  107. {
  108.     if (len > 6) {
  109.         /* check for h264 start code */
  110.         if (AV_RB32(data) == 0x00000001 ||
  111.             AV_RB24(data) == 0x000001) {
  112.             uint8_t *buf=NULL, *end, *start;
  113.             uint32_t sps_size=0, pps_size=0;
  114.             uint8_t *sps=0, *pps=0;
  115.  
  116.             int ret = ff_avc_parse_nal_units_buf(data, &buf, &len);
  117.             if (ret < 0)
  118.                 return ret;
  119.             start = buf;
  120.             end = buf + len;
  121.  
  122.             /* look for sps and pps */
  123.             while (end - buf > 4) {
  124.                 uint32_t size;
  125.                 uint8_t nal_type;
  126.                 size = FFMIN(AV_RB32(buf), end - buf - 4);
  127.                 buf += 4;
  128.                 nal_type = buf[0] & 0x1f;
  129.  
  130.                 if (nal_type == 7) { /* SPS */
  131.                     sps = buf;
  132.                     sps_size = size;
  133.                 } else if (nal_type == 8) { /* PPS */
  134.                     pps = buf;
  135.                     pps_size = size;
  136.                 }
  137.  
  138.                 buf += size;
  139.             }
  140.  
  141.             if (!sps || !pps || sps_size < 4 || sps_size > UINT16_MAX || pps_size > UINT16_MAX)
  142.                 return AVERROR_INVALIDDATA;
  143.  
  144.             avio_w8(pb, 1); /* version */
  145.             avio_w8(pb, sps[1]); /* profile */
  146.             avio_w8(pb, sps[2]); /* profile compat */
  147.             avio_w8(pb, sps[3]); /* level */
  148.             avio_w8(pb, 0xff); /* 6 bits reserved (111111) + 2 bits nal size length - 1 (11) */
  149.             avio_w8(pb, 0xe1); /* 3 bits reserved (111) + 5 bits number of sps (00001) */
  150.  
  151.             avio_wb16(pb, sps_size);
  152.             avio_write(pb, sps, sps_size);
  153.             avio_w8(pb, 1); /* number of pps */
  154.             avio_wb16(pb, pps_size);
  155.             avio_write(pb, pps, pps_size);
  156.             av_free(start);
  157.         } else {
  158.             avio_write(pb, data, len);
  159.         }
  160.     }
  161.     return 0;
  162. }
  163.  
  164. int ff_avc_write_annexb_extradata(const uint8_t *in, uint8_t **buf, int *size)
  165. {
  166.     uint16_t sps_size, pps_size;
  167.     uint8_t *out;
  168.     int out_size;
  169.  
  170.     *buf = NULL;
  171.     if (*size >= 4 && (AV_RB32(in) == 0x00000001 || AV_RB24(in) == 0x000001))
  172.         return 0;
  173.     if (*size < 11 || in[0] != 1)
  174.         return AVERROR_INVALIDDATA;
  175.  
  176.     sps_size = AV_RB16(&in[6]);
  177.     if (11 + sps_size > *size)
  178.         return AVERROR_INVALIDDATA;
  179.     pps_size = AV_RB16(&in[9 + sps_size]);
  180.     if (11 + sps_size + pps_size > *size)
  181.         return AVERROR_INVALIDDATA;
  182.     out_size = 8 + sps_size + pps_size;
  183.     out = av_mallocz(out_size);
  184.     if (!out)
  185.         return AVERROR(ENOMEM);
  186.     AV_WB32(&out[0], 0x00000001);
  187.     memcpy(out + 4, &in[8], sps_size);
  188.     AV_WB32(&out[4 + sps_size], 0x00000001);
  189.     memcpy(out + 8 + sps_size, &in[11 + sps_size], pps_size);
  190.     *buf = out;
  191.     *size = out_size;
  192.     return 0;
  193. }
  194.