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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  if (memcmp(p, ff_asf_file_header, sizeof(ff_asf_guid))) {
58  if (chunksize > end - p)
59  return -1;
60  p += chunksize;
61  continue;
62  }
63 
64  /* skip most of the file header, to min_pktsize */
65  p += 6 * 8 + 3 * 4 + sizeof(ff_asf_guid) * 2;
66  if (p + 8 <= end && AV_RL32(p) == AV_RL32(p + 4)) {
67  /* and set that to zero */
68  AV_WL32(p, 0);
69  return 0;
70  }
71  break;
72  } while (end - p >= sizeof(ff_asf_guid) + 8);
73 
74  return -1;
75 }
76 
77 /**
78  * The following code is basically a buffered AVIOContext,
79  * with the added benefit of returning -EAGAIN (instead of 0)
80  * on packet boundaries, such that the ASF demuxer can return
81  * safely and resume business at the next packet.
82  */
83 static int packetizer_read(void *opaque, uint8_t *buf, int buf_size)
84 {
85  return AVERROR(EAGAIN);
86 }
87 
88 static void init_packetizer(AVIOContext *pb, uint8_t *buf, int len)
89 {
90  ffio_init_context(pb, buf, len, 0, NULL, packetizer_read, NULL, NULL);
91 
92  /* this "fills" the buffer with its current content */
93  pb->pos = len;
94  pb->buf_end = buf + len;
95 }
96 
98 {
99  int ret = 0;
100  if (av_strstart(p, "pgmpu:data:application/vnd.ms.wms-hdr.asfv1;base64,", &p)) {
101  AVIOContext pb;
102  RTSPState *rt = s->priv_data;
103  AVDictionary *opts = NULL;
104  int len = strlen(p) * 6 / 8;
105  char *buf = av_mallocz(len);
107 
108  av_base64_decode(buf, p, len);
109 
110  if (rtp_asf_fix_header(buf, len) < 0)
111  av_log(s, AV_LOG_ERROR,
112  "Failed to fix invalid RTSP-MS/ASF min_pktsize\n");
113  init_packetizer(&pb, buf, len);
114  if (rt->asf_ctx) {
116  }
117  if (!(iformat = av_find_input_format("asf")))
119  if (!(rt->asf_ctx = avformat_alloc_context()))
120  return AVERROR(ENOMEM);
121  rt->asf_ctx->pb = &pb;
122  av_dict_set(&opts, "no_resync_search", "1", 0);
123 
124  if ((ret = ff_copy_whitelists(rt->asf_ctx, s)) < 0) {
125  av_dict_free(&opts);
126  return ret;
127  }
128 
129  ret = avformat_open_input(&rt->asf_ctx, "", iformat, &opts);
130  av_dict_free(&opts);
131  if (ret < 0)
132  return ret;
133  av_dict_copy(&s->metadata, rt->asf_ctx->metadata, 0);
134  rt->asf_pb_pos = avio_tell(&pb);
135  av_free(buf);
136  rt->asf_ctx->pb = NULL;
137  }
138  return ret;
139 }
140 
141 static int asfrtp_parse_sdp_line(AVFormatContext *s, int stream_index,
142  PayloadContext *asf, const char *line)
143 {
144  if (stream_index < 0)
145  return 0;
146  if (av_strstart(line, "stream:", &line)) {
147  RTSPState *rt = s->priv_data;
148 
149  s->streams[stream_index]->id = strtol(line, NULL, 10);
150 
151  if (rt->asf_ctx) {
152  int i;
153 
154  for (i = 0; i < rt->asf_ctx->nb_streams; i++) {
155  if (s->streams[stream_index]->id == rt->asf_ctx->streams[i]->id) {
156  *s->streams[stream_index]->codec =
157  *rt->asf_ctx->streams[i]->codec;
158  s->streams[stream_index]->need_parsing =
159  rt->asf_ctx->streams[i]->need_parsing;
160  rt->asf_ctx->streams[i]->codec->extradata_size = 0;
161  rt->asf_ctx->streams[i]->codec->extradata = NULL;
162  avpriv_set_pts_info(s->streams[stream_index], 32, 1, 1000);
163  }
164  }
165  }
166  }
167 
168  return 0;
169 }
170 
171 struct PayloadContext {
174 };
175 
176 /**
177  * @return 0 when a packet was written into /p pkt, and no more data is left;
178  * 1 when a packet was written into /p pkt, and more packets might be left;
179  * <0 when not enough data was provided to return a full packet, or on error.
180  */
182  AVStream *st, AVPacket *pkt,
183  uint32_t *timestamp,
184  const uint8_t *buf, int len, uint16_t seq,
185  int flags)
186 {
187  AVIOContext *pb = &asf->pb;
188  int res, mflags, len_off;
189  RTSPState *rt = s->priv_data;
190 
191  if (!rt->asf_ctx)
192  return -1;
193 
194  if (len > 0) {
195  int off, out_len = 0;
196 
197  if (len < 4)
198  return -1;
199 
200  av_freep(&asf->buf);
201 
202  ffio_init_context(pb, (uint8_t *)buf, len, 0, NULL, NULL, NULL, NULL);
203 
204  while (avio_tell(pb) + 4 < len) {
205  int start_off = avio_tell(pb);
206 
207  mflags = avio_r8(pb);
208  len_off = avio_rb24(pb);
209  if (mflags & 0x20) /**< relative timestamp */
210  avio_skip(pb, 4);
211  if (mflags & 0x10) /**< has duration */
212  avio_skip(pb, 4);
213  if (mflags & 0x8) /**< has location ID */
214  avio_skip(pb, 4);
215  off = avio_tell(pb);
216 
217  if (!(mflags & 0x40)) {
218  /**
219  * If 0x40 is not set, the len_off field specifies an offset
220  * of this packet's payload data in the complete (reassembled)
221  * ASF packet. This is used to spread one ASF packet over
222  * multiple RTP packets.
223  */
224  if (asf->pktbuf && len_off != avio_tell(asf->pktbuf)) {
225  ffio_free_dyn_buf(&asf->pktbuf);
226  }
227  if (!len_off && !asf->pktbuf &&
228  (res = avio_open_dyn_buf(&asf->pktbuf)) < 0)
229  return res;
230  if (!asf->pktbuf)
231  return AVERROR(EIO);
232 
233  avio_write(asf->pktbuf, buf + off, len - off);
234  avio_skip(pb, len - off);
235  if (!(flags & RTP_FLAG_MARKER))
236  return -1;
237  out_len = avio_close_dyn_buf(asf->pktbuf, &asf->buf);
238  asf->pktbuf = NULL;
239  } else {
240  /**
241  * If 0x40 is set, the len_off field specifies the length of
242  * the next ASF packet that can be read from this payload
243  * data alone. This is commonly the same as the payload size,
244  * but could be less in case of packet splitting (i.e.
245  * multiple ASF packets in one RTP packet).
246  */
247 
248  int cur_len = start_off + len_off - off;
249  int prev_len = out_len;
250  out_len += cur_len;
251  if (FFMIN(cur_len, len - off) < 0)
252  return -1;
253  if ((res = av_reallocp(&asf->buf, out_len)) < 0)
254  return res;
255  memcpy(asf->buf + prev_len, buf + off,
256  FFMIN(cur_len, len - off));
257  avio_skip(pb, cur_len);
258  }
259  }
260 
261  init_packetizer(pb, asf->buf, out_len);
262  pb->pos += rt->asf_pb_pos;
263  pb->eof_reached = 0;
264  rt->asf_ctx->pb = pb;
265  }
266 
267  for (;;) {
268  int i;
269 
270  res = ff_read_packet(rt->asf_ctx, pkt);
271  rt->asf_pb_pos = avio_tell(pb);
272  if (res != 0)
273  break;
274  for (i = 0; i < s->nb_streams; i++) {
275  if (s->streams[i]->id == rt->asf_ctx->streams[pkt->stream_index]->id) {
276  pkt->stream_index = i;
277  return 1; // FIXME: return 0 if last packet
278  }
279  }
280  av_free_packet(pkt);
281  }
282 
283  return res == 1 ? -1 : res;
284 }
285 
287 {
288  ffio_free_dyn_buf(&asf->pktbuf);
289  av_freep(&asf->buf);
290 }
291 
292 #define RTP_ASF_HANDLER(n, s, t) \
293 RTPDynamicProtocolHandler ff_ms_rtp_ ## n ## _handler = { \
294  .enc_name = s, \
295  .codec_type = t, \
296  .codec_id = AV_CODEC_ID_NONE, \
297  .priv_data_size = sizeof(PayloadContext), \
298  .parse_sdp_a_line = asfrtp_parse_sdp_line, \
299  .close = asfrtp_close_context, \
300  .parse_packet = asfrtp_parse_packet, \
301 }
302 
303 RTP_ASF_HANDLER(asf_pfv, "x-asf-pf", AVMEDIA_TYPE_VIDEO);
304 RTP_ASF_HANDLER(asf_pfa, "x-asf-pf", AVMEDIA_TYPE_AUDIO);