libavformat/rtpenc_jpeg.c

   1 /*
   2  * RTP JPEG-compressed video Packetizer, RFC 2435
   3  * Copyright (c) 2012 Samuel Pitoiset
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "libavcodec/bytestream.h"
  23 #include "libavcodec/mjpeg.h"
  24 #include "libavutil/intreadwrite.h"
  25 #include "rtpenc.h"
  26
  27 void ff_rtp_send_jpeg(AVFormatContext *s1, const uint8_t *buf, int size)
  28 {
  29     RTPMuxContext *s = s1->priv_data;
  30     const uint8_t *qtables = NULL;
  31     int nb_qtables = 0;
  32     uint8_t type = 1; /* default pixel format is AV_PIX_FMT_YUVJ420P */
  33     uint8_t w, h;
  34     uint8_t *p;
  35     int off = 0; /* fragment offset of the current JPEG frame */
  36     int len;
  37     int i;
  38
  39     s->buf_ptr   = s->buf;
  40     s->timestamp = s->cur_timestamp;
  41
  42     /* convert video pixel dimensions from pixels to blocks */
  43     w = s1->streams[0]->codec->width  >> 3;
  44     h = s1->streams[0]->codec->height >> 3;
  45
  46     /* check if pixel format is not the normal 420 case */
  47     if (s1->streams[0]->codec->pix_fmt == AV_PIX_FMT_YUVJ422P) {
  48         type = 0;
  49     } else if (s1->streams[0]->codec->pix_fmt == AV_PIX_FMT_YUVJ420P) {
  50         type = 1;
  51     } else {
  52         av_log(s1, AV_LOG_ERROR, "Unsupported pixel format\n");
  53         return;
  54     }
  55
  56     /* preparse the header for getting some infos */
  57     for (i = 0; i < size; i++) {
  58         if (buf[i] != 0xff)
  59             continue;
  60
  61         if (buf[i + 1] == DQT) {
  62             if (buf[i + 4])
  63                 av_log(s1, AV_LOG_WARNING,
  64                        "Only 8-bit precision is supported.\n");
  65
  66             /* a quantization table is 64 bytes long */
  67             nb_qtables = AV_RB16(&buf[i + 2]) / 65;
  68             if (i + 4 + nb_qtables * 65 > size) {
  69                 av_log(s1, AV_LOG_ERROR, "Too short JPEG header. Aborted!\n");
  70                 return;
  71             }
  72
  73             qtables = &buf[i + 4];
  74         } else if (buf[i + 1] == SOF0) {
  75             if (buf[i + 14] != 17 || buf[i + 17] != 17) {
  76                 av_log(s1, AV_LOG_ERROR,
  77                        "Only 1x1 chroma blocks are supported. Aborted!\n");
  78                 return;
  79             }
  80         } else if (buf[i + 1] == SOS) {
  81             /* SOS is last marker in the header */
  82             i += AV_RB16(&buf[i + 2]) + 2;
  83             break;
  84         }
  85     }
  86
  87     /* skip JPEG header */
  88     buf  += i;
  89     size -= i;
  90
  91     for (i = size - 2; i >= 0; i--) {
  92         if (buf[i] == 0xff && buf[i + 1] == EOI) {
  93             /* Remove the EOI marker */
  94             size = i;
  95             break;
  96         }
  97     }
  98
  99     p = s->buf_ptr;
 100     while (size > 0) {
 101         int hdr_size = 8;
 102
 103         if (off == 0 && nb_qtables)
 104             hdr_size += 4 + 64 * nb_qtables;
 105
 106         /* payload max in one packet */
 107         len = FFMIN(size, s->max_payload_size - hdr_size);
 108
 109         /* set main header */
 110         bytestream_put_byte(&p, 0);
 111         bytestream_put_be24(&p, off);
 112         bytestream_put_byte(&p, type);
 113         bytestream_put_byte(&p, 255);
 114         bytestream_put_byte(&p, w);
 115         bytestream_put_byte(&p, h);
 116
 117         if (off == 0 && nb_qtables) {
 118             /* set quantization tables header */
 119             bytestream_put_byte(&p, 0);
 120             bytestream_put_byte(&p, 0);
 121             bytestream_put_be16(&p, 64 * nb_qtables);
 122
 123             for (i = 0; i < nb_qtables; i++)
 124                 bytestream_put_buffer(&p, &qtables[65 * i + 1], 64);
 125         }
 126
 127         /* copy payload data */
 128         memcpy(p, buf, len);
 129
 130         /* marker bit is last packet in frame */
 131         ff_rtp_send_data(s1, s->buf, len + hdr_size, size == len);
 132
 133         buf  += len;
 134         size -= len;
 135         off  += len;
 136         p     = s->buf;
 137     }
 138 }