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  1. /*
  2.  * RTP packetization for H.264 (RFC3984)
  3.  * Copyright (c) 2008 Luca Abeni
  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. /**
  23.  * @file
  24.  * @brief H.264 packetization
  25.  * @author Luca Abeni <lucabe72@email.it>
  26.  */
  27.  
  28. #include "avformat.h"
  29. #include "avc.h"
  30. #include "rtpenc.h"
  31.  
  32. static const uint8_t *avc_mp4_find_startcode(const uint8_t *start, const uint8_t *end, int nal_length_size)
  33. {
  34.     unsigned int res = 0;
  35.  
  36.     if (end - start < nal_length_size)
  37.         return NULL;
  38.     while (nal_length_size--)
  39.         res = (res << 8) | *start++;
  40.  
  41.     if (res > end - start)
  42.         return NULL;
  43.  
  44.     return start + res;
  45. }
  46.  
  47. static void nal_send(AVFormatContext *s1, const uint8_t *buf, int size, int last)
  48. {
  49.     RTPMuxContext *s = s1->priv_data;
  50.  
  51.     av_log(s1, AV_LOG_DEBUG, "Sending NAL %x of len %d M=%d\n", buf[0] & 0x1F, size, last);
  52.     if (size <= s->max_payload_size) {
  53.         ff_rtp_send_data(s1, buf, size, last);
  54.     } else {
  55.         uint8_t type = buf[0] & 0x1F;
  56.         uint8_t nri = buf[0] & 0x60;
  57.  
  58.         if (s->flags & FF_RTP_FLAG_H264_MODE0) {
  59.             av_log(s1, AV_LOG_ERROR,
  60.                    "NAL size %d > %d, try -slice-max-size %d\n", size,
  61.                    s->max_payload_size, s->max_payload_size);
  62.             return;
  63.         }
  64.         av_log(s1, AV_LOG_DEBUG, "NAL size %d > %d\n", size, s->max_payload_size);
  65.         s->buf[0] = 28;        /* FU Indicator; Type = 28 ---> FU-A */
  66.         s->buf[0] |= nri;
  67.         s->buf[1] = type;
  68.         s->buf[1] |= 1 << 7;
  69.         buf += 1;
  70.         size -= 1;
  71.         while (size + 2 > s->max_payload_size) {
  72.             memcpy(&s->buf[2], buf, s->max_payload_size - 2);
  73.             ff_rtp_send_data(s1, s->buf, s->max_payload_size, 0);
  74.             buf += s->max_payload_size - 2;
  75.             size -= s->max_payload_size - 2;
  76.             s->buf[1] &= ~(1 << 7);
  77.         }
  78.         s->buf[1] |= 1 << 6;
  79.         memcpy(&s->buf[2], buf, size);
  80.         ff_rtp_send_data(s1, s->buf, size + 2, last);
  81.     }
  82. }
  83.  
  84. void ff_rtp_send_h264(AVFormatContext *s1, const uint8_t *buf1, int size)
  85. {
  86.     const uint8_t *r, *end = buf1 + size;
  87.     RTPMuxContext *s = s1->priv_data;
  88.  
  89.     s->timestamp = s->cur_timestamp;
  90.     if (s->nal_length_size)
  91.         r = avc_mp4_find_startcode(buf1, end, s->nal_length_size) ? buf1 : end;
  92.     else
  93.         r = ff_avc_find_startcode(buf1, end);
  94.     while (r < end) {
  95.         const uint8_t *r1;
  96.  
  97.         if (s->nal_length_size) {
  98.             r1 = avc_mp4_find_startcode(r, end, s->nal_length_size);
  99.             if (!r1)
  100.                 r1 = end;
  101.             r += s->nal_length_size;
  102.         } else {
  103.             while (!*(r++));
  104.             r1 = ff_avc_find_startcode(r, end);
  105.         }
  106.         nal_send(s1, r, r1 - r, r1 == end);
  107.         r = r1;
  108.     }
  109. }
  110.