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rtpdec_asf.c
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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/avassert.h"
29 #include "libavutil/base64.h"
30 #include "libavutil/avstring.h"
31 #include "libavutil/intreadwrite.h"
32 #include "rtp.h"
33 #include "rtpdec_formats.h"
34 #include "rtsp.h"
35 #include "asf.h"
36 #include "avio_internal.h"
37 #include "internal.h"
38 
39 /**
40  * From MSDN 2.2.1.4, we learn that ASF data packets over RTP should not
41  * contain any padding. Unfortunately, the header min/max_pktsize are not
42  * updated (thus making min_pktsize invalid). Here, we "fix" these faulty
43  * min_pktsize values in the ASF file header.
44  * @return 0 on success, <0 on failure (currently -1).
45  */
46 static int rtp_asf_fix_header(uint8_t *buf, int len)
47 {
48  uint8_t *p = buf, *end = buf + len;
49 
50  if (len < sizeof(ff_asf_guid) * 2 + 22 ||
51  memcmp(p, ff_asf_header, sizeof(ff_asf_guid))) {
52  return -1;
53  }
54  p += sizeof(ff_asf_guid) + 14;
55  do {
56  uint64_t chunksize = AV_RL64(p + sizeof(ff_asf_guid));
57  int skip = 6 * 8 + 3 * 4 + sizeof(ff_asf_guid) * 2;
58  if (memcmp(p, ff_asf_file_header, sizeof(ff_asf_guid))) {
59  if (chunksize > end - p)
60  return -1;
61  p += chunksize;
62  continue;
63  }
64 
65  if (end - p < 8 + skip)
66  break;
67  /* skip most of the file header, to min_pktsize */
68  p += skip;
69  if (AV_RL32(p) == AV_RL32(p + 4)) {
70  /* and set that to zero */
71  AV_WL32(p, 0);
72  return 0;
73  }
74  break;
75  } while (end - p >= sizeof(ff_asf_guid) + 8);
76 
77  return -1;
78 }
79 
80 /**
81  * The following code is basically a buffered AVIOContext,
82  * with the added benefit of returning -EAGAIN (instead of 0)
83  * on packet boundaries, such that the ASF demuxer can return
84  * safely and resume business at the next packet.
85  */
86 static int packetizer_read(void *opaque, uint8_t *buf, int buf_size)
87 {
88  return AVERROR(EAGAIN);
89 }
90 
91 static void init_packetizer(AVIOContext *pb, uint8_t *buf, int len)
92 {
93  ffio_init_context(pb, buf, len, 0, NULL, packetizer_read, NULL, NULL);
94 
95  /* this "fills" the buffer with its current content */
96  pb->pos = len;
97  pb->buf_end = buf + len;
98 }
99 
101 {
102  int ret = 0;
103  if (av_strstart(p, "pgmpu:data:application/vnd.ms.wms-hdr.asfv1;base64,", &p)) {
104  AVIOContext pb;
105  RTSPState *rt = s->priv_data;
106  AVDictionary *opts = NULL;
107  int len = strlen(p) * 6 / 8;
108  char *buf = av_mallocz(len);
110 
111  av_base64_decode(buf, p, len);
112 
113  if (rtp_asf_fix_header(buf, len) < 0)
114  av_log(s, AV_LOG_ERROR,
115  "Failed to fix invalid RTSP-MS/ASF min_pktsize\n");
116  init_packetizer(&pb, buf, len);
117  if (rt->asf_ctx) {
119  }
120  if (!(iformat = av_find_input_format("asf")))
122  if (!(rt->asf_ctx = avformat_alloc_context()))
123  return AVERROR(ENOMEM);
124  rt->asf_ctx->pb = &pb;
125  av_dict_set(&opts, "no_resync_search", "1", 0);
126 
127  if ((ret = ff_copy_whitelists(rt->asf_ctx, s)) < 0) {
128  av_dict_free(&opts);
129  return ret;
130  }
131 
132  ret = avformat_open_input(&rt->asf_ctx, "", iformat, &opts);
133  av_dict_free(&opts);
134  if (ret < 0)
135  return ret;
136  av_dict_copy(&s->metadata, rt->asf_ctx->metadata, 0);
137  rt->asf_pb_pos = avio_tell(&pb);
138  av_free(buf);
139  rt->asf_ctx->pb = NULL;
140  }
141  return ret;
142 }
143 
144 static int asfrtp_parse_sdp_line(AVFormatContext *s, int stream_index,
145  PayloadContext *asf, const char *line)
146 {
147  if (stream_index < 0)
148  return 0;
149  if (av_strstart(line, "stream:", &line)) {
150  RTSPState *rt = s->priv_data;
151 
152  s->streams[stream_index]->id = strtol(line, NULL, 10);
153 
154  if (rt->asf_ctx) {
155  int i;
156 
157  for (i = 0; i < rt->asf_ctx->nb_streams; i++) {
158  if (s->streams[stream_index]->id == rt->asf_ctx->streams[i]->id) {
159  *s->streams[stream_index]->codec =
160  *rt->asf_ctx->streams[i]->codec;
161  s->streams[stream_index]->need_parsing =
162  rt->asf_ctx->streams[i]->need_parsing;
163  rt->asf_ctx->streams[i]->codec->extradata_size = 0;
164  rt->asf_ctx->streams[i]->codec->extradata = NULL;
165  avpriv_set_pts_info(s->streams[stream_index], 32, 1, 1000);
166  }
167  }
168  }
169  }
170 
171  return 0;
172 }
173 
174 struct PayloadContext {
177 };
178 
179 /**
180  * @return 0 when a packet was written into /p pkt, and no more data is left;
181  * 1 when a packet was written into /p pkt, and more packets might be left;
182  * <0 when not enough data was provided to return a full packet, or on error.
183  */
185  AVStream *st, AVPacket *pkt,
186  uint32_t *timestamp,
187  const uint8_t *buf, int len, uint16_t seq,
188  int flags)
189 {
190  AVIOContext *pb = &asf->pb;
191  int res, mflags, len_off;
192  RTSPState *rt = s->priv_data;
193 
194  if (!rt->asf_ctx)
195  return -1;
196 
197  if (len > 0) {
198  int off, out_len = 0;
199 
200  if (len < 4)
201  return -1;
202 
203  av_freep(&asf->buf);
204 
205  ffio_init_context(pb, (uint8_t *)buf, len, 0, NULL, NULL, NULL, NULL);
206 
207  while (avio_tell(pb) + 4 < len) {
208  int start_off = avio_tell(pb);
209 
210  mflags = avio_r8(pb);
211  len_off = avio_rb24(pb);
212  if (mflags & 0x20) /**< relative timestamp */
213  avio_skip(pb, 4);
214  if (mflags & 0x10) /**< has duration */
215  avio_skip(pb, 4);
216  if (mflags & 0x8) /**< has location ID */
217  avio_skip(pb, 4);
218  off = avio_tell(pb);
219 
220  if (!(mflags & 0x40)) {
221  /**
222  * If 0x40 is not set, the len_off field specifies an offset
223  * of this packet's payload data in the complete (reassembled)
224  * ASF packet. This is used to spread one ASF packet over
225  * multiple RTP packets.
226  */
227  if (asf->pktbuf && len_off != avio_tell(asf->pktbuf)) {
228  ffio_free_dyn_buf(&asf->pktbuf);
229  }
230  if (!len_off && !asf->pktbuf &&
231  (res = avio_open_dyn_buf(&asf->pktbuf)) < 0)
232  return res;
233  if (!asf->pktbuf)
234  return AVERROR(EIO);
235 
236  avio_write(asf->pktbuf, buf + off, len - off);
237  avio_skip(pb, len - off);
238  if (!(flags & RTP_FLAG_MARKER))
239  return -1;
240  out_len = avio_close_dyn_buf(asf->pktbuf, &asf->buf);
241  asf->pktbuf = NULL;
242  } else {
243  /**
244  * If 0x40 is set, the len_off field specifies the length of
245  * the next ASF packet that can be read from this payload
246  * data alone. This is commonly the same as the payload size,
247  * but could be less in case of packet splitting (i.e.
248  * multiple ASF packets in one RTP packet).
249  */
250 
251  int cur_len = start_off + len_off - off;
252  int prev_len = out_len;
253  out_len += cur_len;
254  if (FFMIN(cur_len, len - off) < 0)
255  return -1;
256  if ((res = av_reallocp(&asf->buf, out_len)) < 0)
257  return res;
258  memcpy(asf->buf + prev_len, buf + off,
259  FFMIN(cur_len, len - off));
260  avio_skip(pb, cur_len);
261  }
262  }
263 
264  init_packetizer(pb, asf->buf, out_len);
265  pb->pos += rt->asf_pb_pos;
266  pb->eof_reached = 0;
267  rt->asf_ctx->pb = pb;
268  }
269 
270  for (;;) {
271  int i;
272 
273  res = ff_read_packet(rt->asf_ctx, pkt);
274  rt->asf_pb_pos = avio_tell(pb);
275  if (res != 0)
276  break;
277  for (i = 0; i < s->nb_streams; i++) {
278  if (s->streams[i]->id == rt->asf_ctx->streams[pkt->stream_index]->id) {
279  pkt->stream_index = i;
280  return 1; // FIXME: return 0 if last packet
281  }
282  }
283  av_free_packet(pkt);
284  }
285 
286  return res == 1 ? -1 : res;
287 }
288 
290 {
291  ffio_free_dyn_buf(&asf->pktbuf);
292  av_freep(&asf->buf);
293 }
294 
295 #define RTP_ASF_HANDLER(n, s, t) \
296 RTPDynamicProtocolHandler ff_ms_rtp_ ## n ## _handler = { \
297  .enc_name = s, \
298  .codec_type = t, \
299  .codec_id = AV_CODEC_ID_NONE, \
300  .priv_data_size = sizeof(PayloadContext), \
301  .parse_sdp_a_line = asfrtp_parse_sdp_line, \
302  .close = asfrtp_close_context, \
303  .parse_packet = asfrtp_parse_packet, \
304 }
305 
306 RTP_ASF_HANDLER(asf_pfv, "x-asf-pf", AVMEDIA_TYPE_VIDEO);
307 RTP_ASF_HANDLER(asf_pfa, "x-asf-pf", AVMEDIA_TYPE_AUDIO);