FFmpeg
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
rtpdec_asf.c
Go to the documentation of this file.
1 /*
2  * Microsoft RTP/ASF support.
3  * Copyright (c) 2008 Ronald S. Bultje
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 Microsoft RTP/ASF support
25  * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
26  */
27 
28 #include "libavutil/base64.h"
29 #include "libavutil/avstring.h"
30 #include "libavutil/intreadwrite.h"
31 #include "rtp.h"
32 #include "rtpdec_formats.h"
33 #include "rtsp.h"
34 #include "asf.h"
35 #include "avio_internal.h"
36 #include "internal.h"
37 
38 /**
39  * From MSDN 2.2.1.4, we learn that ASF data packets over RTP should not
40  * contain any padding. Unfortunately, the header min/max_pktsize are not
41  * updated (thus making min_pktsize invalid). Here, we "fix" these faulty
42  * min_pktsize values in the ASF file header.
43  * @return 0 on success, <0 on failure (currently -1).
44  */
45 static int rtp_asf_fix_header(uint8_t *buf, int len)
46 {
47  uint8_t *p = buf, *end = buf + len;
48 
49  if (len < sizeof(ff_asf_guid) * 2 + 22 ||
50  memcmp(p, ff_asf_header, sizeof(ff_asf_guid))) {
51  return -1;
52  }
53  p += sizeof(ff_asf_guid) + 14;
54  do {
55  uint64_t chunksize = AV_RL64(p + sizeof(ff_asf_guid));
56  if (memcmp(p, ff_asf_file_header, sizeof(ff_asf_guid))) {
57  if (chunksize > end - p)
58  return -1;
59  p += chunksize;
60  continue;
61  }
62 
63  /* skip most of the file header, to min_pktsize */
64  p += 6 * 8 + 3 * 4 + sizeof(ff_asf_guid) * 2;
65  if (p + 8 <= end && AV_RL32(p) == AV_RL32(p + 4)) {
66  /* and set that to zero */
67  AV_WL32(p, 0);
68  return 0;
69  }
70  break;
71  } while (end - p >= sizeof(ff_asf_guid) + 8);
72 
73  return -1;
74 }
75 
76 /**
77  * The following code is basically a buffered AVIOContext,
78  * with the added benefit of returning -EAGAIN (instead of 0)
79  * on packet boundaries, such that the ASF demuxer can return
80  * safely and resume business at the next packet.
81  */
82 static int packetizer_read(void *opaque, uint8_t *buf, int buf_size)
83 {
84  return AVERROR(EAGAIN);
85 }
86 
87 static void init_packetizer(AVIOContext *pb, uint8_t *buf, int len)
88 {
89  ffio_init_context(pb, buf, len, 0, NULL, packetizer_read, NULL, NULL);
90 
91  /* this "fills" the buffer with its current content */
92  pb->pos = len;
93  pb->buf_end = buf + len;
94 }
95 
97 {
98  int ret = 0;
99  if (av_strstart(p, "pgmpu:data:application/vnd.ms.wms-hdr.asfv1;base64,", &p)) {
100  AVIOContext pb;
101  RTSPState *rt = s->priv_data;
102  AVDictionary *opts = NULL;
103  int len = strlen(p) * 6 / 8;
104  char *buf = av_mallocz(len);
105  av_base64_decode(buf, p, len);
106 
107  if (rtp_asf_fix_header(buf, len) < 0)
108  av_log(s, AV_LOG_ERROR,
109  "Failed to fix invalid RTSP-MS/ASF min_pktsize\n");
110  init_packetizer(&pb, buf, len);
111  if (rt->asf_ctx) {
113  }
114  if (!(rt->asf_ctx = avformat_alloc_context()))
115  return AVERROR(ENOMEM);
116  rt->asf_ctx->pb = &pb;
117  av_dict_set(&opts, "no_resync_search", "1", 0);
118  ret = avformat_open_input(&rt->asf_ctx, "", &ff_asf_demuxer, &opts);
119  av_dict_free(&opts);
120  if (ret < 0)
121  return ret;
122  av_dict_copy(&s->metadata, rt->asf_ctx->metadata, 0);
123  rt->asf_pb_pos = avio_tell(&pb);
124  av_free(buf);
125  rt->asf_ctx->pb = NULL;
126  }
127  return ret;
128 }
129 
130 static int asfrtp_parse_sdp_line(AVFormatContext *s, int stream_index,
131  PayloadContext *asf, const char *line)
132 {
133  if (stream_index < 0)
134  return 0;
135  if (av_strstart(line, "stream:", &line)) {
136  RTSPState *rt = s->priv_data;
137 
138  s->streams[stream_index]->id = strtol(line, NULL, 10);
139 
140  if (rt->asf_ctx) {
141  int i;
142 
143  for (i = 0; i < rt->asf_ctx->nb_streams; i++) {
144  if (s->streams[stream_index]->id == rt->asf_ctx->streams[i]->id) {
145  *s->streams[stream_index]->codec =
146  *rt->asf_ctx->streams[i]->codec;
147  rt->asf_ctx->streams[i]->codec->extradata_size = 0;
148  rt->asf_ctx->streams[i]->codec->extradata = NULL;
149  avpriv_set_pts_info(s->streams[stream_index], 32, 1, 1000);
150  }
151  }
152  }
153  }
154 
155  return 0;
156 }
157 
158 struct PayloadContext {
161 };
162 
163 /**
164  * @return 0 when a packet was written into /p pkt, and no more data is left;
165  * 1 when a packet was written into /p pkt, and more packets might be left;
166  * <0 when not enough data was provided to return a full packet, or on error.
167  */
169  AVStream *st, AVPacket *pkt,
170  uint32_t *timestamp,
171  const uint8_t *buf, int len, uint16_t seq,
172  int flags)
173 {
174  AVIOContext *pb = &asf->pb;
175  int res, mflags, len_off;
176  RTSPState *rt = s->priv_data;
177 
178  if (!rt->asf_ctx)
179  return -1;
180 
181  if (len > 0) {
182  int off, out_len = 0;
183 
184  if (len < 4)
185  return -1;
186 
187  av_freep(&asf->buf);
188 
189  ffio_init_context(pb, buf, len, 0, NULL, NULL, NULL, NULL);
190 
191  while (avio_tell(pb) + 4 < len) {
192  int start_off = avio_tell(pb);
193 
194  mflags = avio_r8(pb);
195  if (mflags & 0x80)
196  flags |= RTP_FLAG_KEY;
197  len_off = avio_rb24(pb);
198  if (mflags & 0x20) /**< relative timestamp */
199  avio_skip(pb, 4);
200  if (mflags & 0x10) /**< has duration */
201  avio_skip(pb, 4);
202  if (mflags & 0x8) /**< has location ID */
203  avio_skip(pb, 4);
204  off = avio_tell(pb);
205 
206  if (!(mflags & 0x40)) {
207  /**
208  * If 0x40 is not set, the len_off field specifies an offset
209  * of this packet's payload data in the complete (reassembled)
210  * ASF packet. This is used to spread one ASF packet over
211  * multiple RTP packets.
212  */
213  if (asf->pktbuf && len_off != avio_tell(asf->pktbuf)) {
214  uint8_t *p;
215  avio_close_dyn_buf(asf->pktbuf, &p);
216  asf->pktbuf = NULL;
217  av_free(p);
218  }
219  if (!len_off && !asf->pktbuf &&
220  (res = avio_open_dyn_buf(&asf->pktbuf)) < 0)
221  return res;
222  if (!asf->pktbuf)
223  return AVERROR(EIO);
224 
225  avio_write(asf->pktbuf, buf + off, len - off);
226  avio_skip(pb, len - off);
227  if (!(flags & RTP_FLAG_MARKER))
228  return -1;
229  out_len = avio_close_dyn_buf(asf->pktbuf, &asf->buf);
230  asf->pktbuf = NULL;
231  } else {
232  /**
233  * If 0x40 is set, the len_off field specifies the length of
234  * the next ASF packet that can be read from this payload
235  * data alone. This is commonly the same as the payload size,
236  * but could be less in case of packet splitting (i.e.
237  * multiple ASF packets in one RTP packet).
238  */
239 
240  int cur_len = start_off + len_off - off;
241  int prev_len = out_len;
242  void *newmem;
243  out_len += cur_len;
244  if (FFMIN(cur_len, len - off) < 0)
245  return -1;
246  newmem = av_realloc(asf->buf, out_len);
247  if (!newmem)
248  return -1;
249  asf->buf = newmem;
250  memcpy(asf->buf + prev_len, buf + off,
251  FFMIN(cur_len, len - off));
252  avio_skip(pb, cur_len);
253  }
254  }
255 
256  init_packetizer(pb, asf->buf, out_len);
257  pb->pos += rt->asf_pb_pos;
258  pb->eof_reached = 0;
259  rt->asf_ctx->pb = pb;
260  }
261 
262  for (;;) {
263  int i;
264 
265  res = ff_read_packet(rt->asf_ctx, pkt);
266  rt->asf_pb_pos = avio_tell(pb);
267  if (res != 0)
268  break;
269  for (i = 0; i < s->nb_streams; i++) {
270  if (s->streams[i]->id == rt->asf_ctx->streams[pkt->stream_index]->id) {
271  pkt->stream_index = i;
272  return 1; // FIXME: return 0 if last packet
273  }
274  }
275  av_free_packet(pkt);
276  }
277 
278  return res == 1 ? -1 : res;
279 }
280 
282 {
283  return av_mallocz(sizeof(PayloadContext));
284 }
285 
287 {
288  if (asf->pktbuf) {
289  uint8_t *p = NULL;
290  avio_close_dyn_buf(asf->pktbuf, &p);
291  asf->pktbuf = NULL;
292  av_free(p);
293  }
294  av_freep(&asf->buf);
295  av_free(asf);
296 }
297 
298 #define RTP_ASF_HANDLER(n, s, t) \
299 RTPDynamicProtocolHandler ff_ms_rtp_ ## n ## _handler = { \
300  .enc_name = s, \
301  .codec_type = t, \
302  .codec_id = AV_CODEC_ID_NONE, \
303  .parse_sdp_a_line = asfrtp_parse_sdp_line, \
304  .alloc = asfrtp_new_context, \
305  .free = asfrtp_free_context, \
306  .parse_packet = asfrtp_parse_packet, \
307 }
308 
309 RTP_ASF_HANDLER(asf_pfv, "x-asf-pf", AVMEDIA_TYPE_VIDEO);
310 RTP_ASF_HANDLER(asf_pfa, "x-asf-pf", AVMEDIA_TYPE_AUDIO);