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rtpdec_xiph.c
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1 /*
2  * Xiph RTP Protocols
3  * Copyright (c) 2009 Colin McQuillian
4  * Copyright (c) 2010 Josh Allmann
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * @brief Xiph / RTP Code
26  * @author Colin McQuillan <m.niloc@gmail.com>
27  * @author Josh Allmann <joshua.allmann@gmail.com>
28  */
29 
30 #include "libavutil/avassert.h"
31 #include "libavutil/avstring.h"
32 #include "libavutil/base64.h"
33 #include "libavcodec/bytestream.h"
34 
35 #include "rtpdec.h"
36 #include "rtpdec_formats.h"
37 
38 /**
39  * RTP/Xiph specific private data.
40  */
41 struct PayloadContext {
42  unsigned ident; ///< 24-bit stream configuration identifier
43  uint32_t timestamp;
44  AVIOContext* fragment; ///< buffer for split payloads
48 };
49 
51 {
52  return av_mallocz(sizeof(PayloadContext));
53 }
54 
56 {
57  if (data->fragment) {
58  uint8_t* p;
59  avio_close_dyn_buf(data->fragment, &p);
60  av_free(p);
61  data->fragment = NULL;
62  }
63 }
64 
66 {
68  av_free(data->split_buf);
69  av_free(data);
70 }
71 
72 static int xiph_vorbis_init(AVFormatContext *ctx, int st_index,
74 {
75  if (st_index < 0)
76  return 0;
78  return 0;
79 }
80 
81 
83  AVStream *st, AVPacket *pkt, uint32_t *timestamp,
84  const uint8_t *buf, int len, uint16_t seq,
85  int flags)
86 {
87 
88  int ident, fragmented, tdt, num_pkts, pkt_len;
89 
90  if (!buf) {
91  if (!data->split_buf || data->split_pos + 2 > data->split_buf_len ||
92  data->split_pkts <= 0) {
93  av_log(ctx, AV_LOG_ERROR, "No more data to return\n");
94  return AVERROR_INVALIDDATA;
95  }
96  pkt_len = AV_RB16(data->split_buf + data->split_pos);
97  data->split_pos += 2;
98  if (data->split_pos + pkt_len > data->split_buf_len) {
99  av_log(ctx, AV_LOG_ERROR, "Not enough data to return\n");
100  return AVERROR_INVALIDDATA;
101  }
102  if (av_new_packet(pkt, pkt_len)) {
103  av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
104  return AVERROR(ENOMEM);
105  }
106  pkt->stream_index = st->index;
107  memcpy(pkt->data, data->split_buf + data->split_pos, pkt_len);
108  data->split_pos += pkt_len;
109  data->split_pkts--;
110  return data->split_pkts > 0;
111  }
112 
113  if (len < 6) {
114  av_log(ctx, AV_LOG_ERROR, "Invalid %d byte packet\n", len);
115  return AVERROR_INVALIDDATA;
116  }
117 
118  // read xiph rtp headers
119  ident = AV_RB24(buf);
120  fragmented = buf[3] >> 6;
121  tdt = (buf[3] >> 4) & 3;
122  num_pkts = buf[3] & 0xf;
123  pkt_len = AV_RB16(buf + 4);
124 
125  if (pkt_len > len - 6) {
126  av_log(ctx, AV_LOG_ERROR,
127  "Invalid packet length %d in %d byte packet\n", pkt_len,
128  len);
129  return AVERROR_INVALIDDATA;
130  }
131 
132  if (ident != data->ident) {
133  av_log(ctx, AV_LOG_ERROR,
134  "Unimplemented Xiph SDP configuration change detected\n");
135  return AVERROR_PATCHWELCOME;
136  }
137 
138  if (tdt) {
139  av_log(ctx, AV_LOG_ERROR,
140  "Unimplemented RTP Xiph packet settings (%d,%d,%d)\n",
141  fragmented, tdt, num_pkts);
142  return AVERROR_PATCHWELCOME;
143  }
144 
145  buf += 6; // move past header bits
146  len -= 6;
147 
148  if (fragmented == 0) {
149  if (av_new_packet(pkt, pkt_len)) {
150  av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
151  return AVERROR(ENOMEM);
152  }
153  pkt->stream_index = st->index;
154  memcpy(pkt->data, buf, pkt_len);
155  buf += pkt_len;
156  len -= pkt_len;
157  num_pkts--;
158 
159  if (num_pkts > 0) {
160  if (len > data->split_buf_size || !data->split_buf) {
161  av_freep(&data->split_buf);
162  data->split_buf_size = 2 * len;
163  data->split_buf = av_malloc(data->split_buf_size);
164  if (!data->split_buf) {
165  av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
166  av_free_packet(pkt);
167  return AVERROR(ENOMEM);
168  }
169  }
170  memcpy(data->split_buf, buf, len);
171  data->split_buf_len = len;
172  data->split_pos = 0;
173  data->split_pkts = num_pkts;
174  return 1;
175  }
176 
177  return 0;
178 
179  } else if (fragmented == 1) {
180  // start of xiph data fragment
181  int res;
182 
183  // end packet has been lost somewhere, so drop buffered data
185 
186  if((res = avio_open_dyn_buf(&data->fragment)) < 0)
187  return res;
188 
189  avio_write(data->fragment, buf, pkt_len);
190  data->timestamp = *timestamp;
191 
192  } else {
193  av_assert1(fragmented < 4);
194  if (data->timestamp != *timestamp) {
195  // skip if fragmented timestamp is incorrect;
196  // a start packet has been lost somewhere
198  av_log(ctx, AV_LOG_ERROR, "RTP timestamps don't match!\n");
199  return AVERROR_INVALIDDATA;
200  }
201  if (!data->fragment) {
202  av_log(ctx, AV_LOG_WARNING,
203  "Received packet without a start fragment; dropping.\n");
204  return AVERROR(EAGAIN);
205  }
206 
207  // copy data to fragment buffer
208  avio_write(data->fragment, buf, pkt_len);
209 
210  if (fragmented == 3) {
211  // end of xiph data packet
212  int ret = ff_rtp_finalize_packet(pkt, &data->fragment, st->index);
213  if (ret < 0) {
214  av_log(ctx, AV_LOG_ERROR,
215  "Error occurred when getting fragment buffer.");
216  return ret;
217  }
218 
219  return 0;
220  }
221  }
222 
223  return AVERROR(EAGAIN);
224 }
225 
226 /**
227  * Length encoding described in RFC5215 section 3.1.1.
228  */
229 static int get_base128(const uint8_t ** buf, const uint8_t * buf_end)
230 {
231  int n = 0;
232  for (; *buf < buf_end; ++*buf) {
233  n <<= 7;
234  n += **buf & 0x7f;
235  if (!(**buf & 0x80)) {
236  ++*buf;
237  return n;
238  }
239  }
240  return 0;
241 }
242 
243 /**
244  * Based off parse_packed_headers in Vorbis RTP
245  */
246 static int
247 parse_packed_headers(const uint8_t * packed_headers,
248  const uint8_t * packed_headers_end,
249  AVCodecContext * codec, PayloadContext * xiph_data)
250 {
251 
252  unsigned num_packed, num_headers, length, length1, length2, extradata_alloc;
253  uint8_t *ptr;
254 
255  if (packed_headers_end - packed_headers < 9) {
256  av_log(codec, AV_LOG_ERROR,
257  "Invalid %td byte packed header.",
258  packed_headers_end - packed_headers);
259  return AVERROR_INVALIDDATA;
260  }
261 
262  num_packed = bytestream_get_be32(&packed_headers);
263  xiph_data->ident = bytestream_get_be24(&packed_headers);
264  length = bytestream_get_be16(&packed_headers);
265  num_headers = get_base128(&packed_headers, packed_headers_end);
266  length1 = get_base128(&packed_headers, packed_headers_end);
267  length2 = get_base128(&packed_headers, packed_headers_end);
268 
269  if (num_packed != 1 || num_headers > 3) {
270  av_log(codec, AV_LOG_ERROR,
271  "Unimplemented number of headers: %d packed headers, %d headers\n",
272  num_packed, num_headers);
273  return AVERROR_PATCHWELCOME;
274  }
275 
276  if (packed_headers_end - packed_headers != length ||
277  length1 > length || length2 > length - length1) {
278  av_log(codec, AV_LOG_ERROR,
279  "Bad packed header lengths (%d,%d,%td,%d)\n", length1,
280  length2, packed_headers_end - packed_headers, length);
281  return AVERROR_INVALIDDATA;
282  }
283 
284  /* allocate extra space:
285  * -- length/255 +2 for xiphlacing
286  * -- one for the '2' marker
287  * -- FF_INPUT_BUFFER_PADDING_SIZE required */
288  extradata_alloc = length + length/255 + 3 + FF_INPUT_BUFFER_PADDING_SIZE;
289 
290  ptr = codec->extradata = av_malloc(extradata_alloc);
291  if (!ptr) {
292  av_log(codec, AV_LOG_ERROR, "Out of memory\n");
293  return AVERROR(ENOMEM);
294  }
295  *ptr++ = 2;
296  ptr += av_xiphlacing(ptr, length1);
297  ptr += av_xiphlacing(ptr, length2);
298  memcpy(ptr, packed_headers, length);
299  ptr += length;
300  codec->extradata_size = ptr - codec->extradata;
301  // clear out remaining parts of the buffer
302  memset(ptr, 0, extradata_alloc - codec->extradata_size);
303 
304  return 0;
305 }
306 
307 static int xiph_parse_fmtp_pair(AVStream* stream,
308  PayloadContext *xiph_data,
309  char *attr, char *value)
310 {
311  AVCodecContext *codec = stream->codec;
312  int result = 0;
313 
314  if (!strcmp(attr, "sampling")) {
315  if (!strcmp(value, "YCbCr-4:2:0")) {
316  codec->pix_fmt = AV_PIX_FMT_YUV420P;
317  } else if (!strcmp(value, "YCbCr-4:4:2")) {
318  codec->pix_fmt = AV_PIX_FMT_YUV422P;
319  } else if (!strcmp(value, "YCbCr-4:4:4")) {
320  codec->pix_fmt = AV_PIX_FMT_YUV444P;
321  } else {
322  av_log(codec, AV_LOG_ERROR,
323  "Unsupported pixel format %s\n", attr);
324  return AVERROR_INVALIDDATA;
325  }
326  } else if (!strcmp(attr, "width")) {
327  /* This is an integer between 1 and 1048561
328  * and MUST be in multiples of 16. */
329  codec->width = atoi(value);
330  return 0;
331  } else if (!strcmp(attr, "height")) {
332  /* This is an integer between 1 and 1048561
333  * and MUST be in multiples of 16. */
334  codec->height = atoi(value);
335  return 0;
336  } else if (!strcmp(attr, "delivery-method")) {
337  /* Possible values are: inline, in_band, out_band/specific_name. */
338  return AVERROR_PATCHWELCOME;
339  } else if (!strcmp(attr, "configuration-uri")) {
340  /* NOTE: configuration-uri is supported only under 2 conditions:
341  *--after the delivery-method tag
342  * --with a delivery-method value of out_band */
343  return AVERROR_PATCHWELCOME;
344  } else if (!strcmp(attr, "configuration")) {
345  /* NOTE: configuration is supported only AFTER the delivery-method tag
346  * The configuration value is a base64 encoded packed header */
347  uint8_t *decoded_packet = NULL;
348  int packet_size;
349  size_t decoded_alloc = strlen(value) / 4 * 3 + 4;
350 
351  if (decoded_alloc <= INT_MAX) {
352  decoded_packet = av_malloc(decoded_alloc);
353  if (decoded_packet) {
354  packet_size =
355  av_base64_decode(decoded_packet, value, decoded_alloc);
356 
357  result = parse_packed_headers
358  (decoded_packet, decoded_packet + packet_size, codec,
359  xiph_data);
360  } else {
361  av_log(codec, AV_LOG_ERROR,
362  "Out of memory while decoding SDP configuration.\n");
363  result = AVERROR(ENOMEM);
364  }
365  } else {
366  av_log(codec, AV_LOG_ERROR, "Packet too large\n");
367  result = AVERROR_INVALIDDATA;
368  }
369  av_free(decoded_packet);
370  }
371  return result;
372 }
373 
374 static int xiph_parse_sdp_line(AVFormatContext *s, int st_index,
375  PayloadContext *data, const char *line)
376 {
377  const char *p;
378 
379  if (st_index < 0)
380  return 0;
381 
382  if (av_strstart(line, "fmtp:", &p)) {
383  return ff_parse_fmtp(s->streams[st_index], data, p,
385  }
386 
387  return 0;
388 }
389 
391  .enc_name = "theora",
392  .codec_type = AVMEDIA_TYPE_VIDEO,
393  .codec_id = AV_CODEC_ID_THEORA,
394  .parse_sdp_a_line = xiph_parse_sdp_line,
395  .alloc = xiph_new_context,
396  .free = xiph_free_context,
397  .parse_packet = xiph_handle_packet
398 };
399 
401  .enc_name = "vorbis",
402  .codec_type = AVMEDIA_TYPE_AUDIO,
403  .codec_id = AV_CODEC_ID_VORBIS,
404  .init = xiph_vorbis_init,
405  .parse_sdp_a_line = xiph_parse_sdp_line,
406  .alloc = xiph_new_context,
407  .free = xiph_free_context,
408  .parse_packet = xiph_handle_packet
409 };