Libav
movenchint.c
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1 /*
2  * MOV, 3GP, MP4 muxer RTP hinting
3  * Copyright (c) 2010 Martin Storsjo
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 "movenc.h"
23 #include "libavutil/intreadwrite.h"
24 #include "internal.h"
25 #include "rtpenc_chain.h"
26 #include "avio_internal.h"
27 #include "rtp.h"
28 
29 int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
30 {
31  MOVMuxContext *mov = s->priv_data;
32  MOVTrack *track = &mov->tracks[index];
33  MOVTrack *src_track = &mov->tracks[src_index];
34  AVStream *src_st = s->streams[src_index];
35  int ret = AVERROR(ENOMEM);
36 
37  track->tag = MKTAG('r','t','p',' ');
38  track->src_track = src_index;
39 
41  if (!track->enc)
42  goto fail;
44  track->enc->codec_tag = track->tag;
45 
46  ret = ff_rtp_chain_mux_open(&track->rtp_ctx, s, src_st, NULL,
47  RTP_MAX_PACKET_SIZE, src_index);
48  if (ret < 0)
49  goto fail;
50 
51  /* Copy the RTP AVStream timebase back to the hint AVStream */
52  track->timescale = track->rtp_ctx->streams[0]->time_base.den;
53 
54  /* Mark the hinted track that packets written to it should be
55  * sent to this track for hinting. */
56  src_track->hint_track = index;
57  return 0;
58 fail:
60  "Unable to initialize hinting of stream %d\n", src_index);
61  av_freep(&track->enc);
62  /* Set a default timescale, to avoid crashes in av_dump_format */
63  track->timescale = 90000;
64  return ret;
65 }
66 
70 static void sample_queue_pop(HintSampleQueue *queue)
71 {
72  if (queue->len <= 0)
73  return;
74  if (queue->samples[0].own_data)
75  av_free(queue->samples[0].data);
76  queue->len--;
77  memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);
78 }
79 
84 {
85  int i;
86  for (i = 0; i < queue->len; i++)
87  if (queue->samples[i].own_data)
88  av_free(queue->samples[i].data);
89  av_freep(&queue->samples);
90  queue->len = 0;
91  queue->size = 0;
92 }
93 
100  int sample)
101 {
102  /* No need to keep track of smaller samples, since describing them
103  * with immediates is more efficient. */
104  if (size <= 14)
105  return;
106  if (!queue->samples || queue->len >= queue->size) {
107  queue->size += 10;
108  if (av_reallocp(&queue->samples, sizeof(*queue->samples) * queue->size) < 0) {
109  queue->len = queue->size = 0;
110  return;
111  }
112  }
113  queue->samples[queue->len].data = data;
114  queue->samples[queue->len].size = size;
115  queue->samples[queue->len].sample_number = sample;
116  queue->samples[queue->len].offset = 0;
117  queue->samples[queue->len].own_data = 0;
118  queue->len++;
119 }
120 
125 {
126  int i;
127  for (i = 0; i < queue->len; ) {
128  HintSample *sample = &queue->samples[i];
129  if (!sample->own_data) {
130  uint8_t *ptr = av_malloc(sample->size);
131  if (!ptr) {
132  /* Unable to allocate memory for this one, remove it */
133  memmove(queue->samples + i, queue->samples + i + 1,
134  sizeof(HintSample)*(queue->len - i - 1));
135  queue->len--;
136  continue;
137  }
138  memcpy(ptr, sample->data, sample->size);
139  sample->data = ptr;
140  sample->own_data = 1;
141  }
142  i++;
143  }
144 }
145 
162 static int match_segments(const uint8_t *haystack, int h_len,
163  const uint8_t *needle, int n_pos, int n_len,
164  int *match_h_offset_ptr, int *match_n_offset_ptr,
165  int *match_len_ptr)
166 {
167  int h_pos;
168  for (h_pos = 0; h_pos < h_len; h_pos++) {
169  int match_len = 0;
170  int match_h_pos, match_n_pos;
171 
172  /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
173  while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
174  needle[n_pos + match_len] == haystack[h_pos + match_len])
175  match_len++;
176  if (match_len <= 8)
177  continue;
178 
179  /* If a sufficiently large match was found, try to expand
180  * the matched segment backwards. */
181  match_h_pos = h_pos;
182  match_n_pos = n_pos;
183  while (match_n_pos > 0 && match_h_pos > 0 &&
184  needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
185  match_n_pos--;
186  match_h_pos--;
187  match_len++;
188  }
189  if (match_len <= 14)
190  continue;
191  *match_h_offset_ptr = match_h_pos;
192  *match_n_offset_ptr = match_n_pos;
193  *match_len_ptr = match_len;
194  return 0;
195  }
196  return -1;
197 }
198 
214 static int find_sample_match(const uint8_t *data, int len,
215  HintSampleQueue *queue, int *pos,
216  int *match_sample, int *match_offset,
217  int *match_len)
218 {
219  while (queue->len > 0) {
220  HintSample *sample = &queue->samples[0];
221  /* If looking for matches in a new sample, skip the first 5 bytes,
222  * since they often may be modified/removed in the output packet. */
223  if (sample->offset == 0 && sample->size > 5)
224  sample->offset = 5;
225 
226  if (match_segments(data, len, sample->data, sample->offset,
227  sample->size, pos, match_offset, match_len) == 0) {
228  *match_sample = sample->sample_number;
229  /* Next time, look for matches at this offset, with a little
230  * margin to this match. */
231  sample->offset = *match_offset + *match_len + 5;
232  if (sample->offset + 10 >= sample->size)
233  sample_queue_pop(queue); /* Not enough useful data left */
234  return 0;
235  }
236 
237  if (sample->offset < 10 && sample->size > 20) {
238  /* No match found from the start of the sample,
239  * try from the middle of the sample instead. */
240  sample->offset = sample->size/2;
241  } else {
242  /* No match for this sample, remove it */
243  sample_queue_pop(queue);
244  }
245  }
246  return -1;
247 }
248 
249 static void output_immediate(const uint8_t *data, int size,
250  AVIOContext *out, int *entries)
251 {
252  while (size > 0) {
253  int len = size;
254  if (len > 14)
255  len = 14;
256  avio_w8(out, 1); /* immediate constructor */
257  avio_w8(out, len); /* amount of valid data */
258  avio_write(out, data, len);
259  data += len;
260  size -= len;
261 
262  for (; len < 14; len++)
263  avio_w8(out, 0);
264 
265  (*entries)++;
266  }
267 }
268 
269 static void output_match(AVIOContext *out, int match_sample,
270  int match_offset, int match_len, int *entries)
271 {
272  avio_w8(out, 2); /* sample constructor */
273  avio_w8(out, 0); /* track reference */
274  avio_wb16(out, match_len);
275  avio_wb32(out, match_sample);
276  avio_wb32(out, match_offset);
277  avio_wb16(out, 1); /* bytes per block */
278  avio_wb16(out, 1); /* samples per block */
279  (*entries)++;
280 }
281 
282 static void describe_payload(const uint8_t *data, int size,
283  AVIOContext *out, int *entries,
284  HintSampleQueue *queue)
285 {
286  /* Describe the payload using different constructors */
287  while (size > 0) {
288  int match_sample, match_offset, match_len, pos;
289  if (find_sample_match(data, size, queue, &pos, &match_sample,
290  &match_offset, &match_len) < 0)
291  break;
292  output_immediate(data, pos, out, entries);
293  data += pos;
294  size -= pos;
295  output_match(out, match_sample, match_offset, match_len, entries);
296  data += match_len;
297  size -= match_len;
298  }
299  output_immediate(data, size, out, entries);
300 }
301 
315  int size, MOVTrack *trk, int64_t *dts)
316 {
317  int64_t curpos;
318  int64_t count_pos, entries_pos;
319  int count = 0, entries;
320 
321  count_pos = avio_tell(out);
322  /* RTPsample header */
323  avio_wb16(out, 0); /* packet count */
324  avio_wb16(out, 0); /* reserved */
325 
326  while (size > 4) {
327  uint32_t packet_len = AV_RB32(data);
328  uint16_t seq;
329  uint32_t ts;
330  int32_t ts_diff;
331 
332  data += 4;
333  size -= 4;
334  if (packet_len > size || packet_len <= 12)
335  break;
336  if (RTP_PT_IS_RTCP(data[1])) {
337  /* RTCP packet, just skip */
338  data += packet_len;
339  size -= packet_len;
340  continue;
341  }
342 
343  if (packet_len > trk->max_packet_size)
344  trk->max_packet_size = packet_len;
345 
346  seq = AV_RB16(&data[2]);
347  ts = AV_RB32(&data[4]);
348 
349  if (trk->prev_rtp_ts == 0)
350  trk->prev_rtp_ts = ts;
351  /* Unwrap the 32-bit RTP timestamp that wraps around often
352  * into a not (as often) wrapping 64-bit timestamp. */
353  ts_diff = ts - trk->prev_rtp_ts;
354  if (ts_diff > 0) {
355  trk->cur_rtp_ts_unwrapped += ts_diff;
356  trk->prev_rtp_ts = ts;
357  ts_diff = 0;
358  }
359  if (*dts == AV_NOPTS_VALUE)
360  *dts = trk->cur_rtp_ts_unwrapped;
361 
362  count++;
363  /* RTPpacket header */
364  avio_wb32(out, 0); /* relative_time */
365  avio_write(out, data, 2); /* RTP header */
366  avio_wb16(out, seq); /* RTPsequenceseed */
367  avio_wb16(out, ts_diff ? 4 : 0); /* reserved + flags (extra_flag) */
368  entries_pos = avio_tell(out);
369  avio_wb16(out, 0); /* entry count */
370  if (ts_diff) { /* if extra_flag is set */
371  avio_wb32(out, 16); /* extra_information_length */
372  avio_wb32(out, 12); /* rtpoffsetTLV box */
373  avio_write(out, "rtpo", 4);
374  avio_wb32(out, ts_diff);
375  }
376 
377  data += 12;
378  size -= 12;
379  packet_len -= 12;
380 
381  entries = 0;
382  /* Write one or more constructors describing the payload data */
383  describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
384  data += packet_len;
385  size -= packet_len;
386 
387  curpos = avio_tell(out);
388  avio_seek(out, entries_pos, SEEK_SET);
389  avio_wb16(out, entries);
390  avio_seek(out, curpos, SEEK_SET);
391  }
392 
393  curpos = avio_tell(out);
394  avio_seek(out, count_pos, SEEK_SET);
395  avio_wb16(out, count);
396  avio_seek(out, curpos, SEEK_SET);
397  return count;
398 }
399 
401  int track_index, int sample,
402  uint8_t *sample_data, int sample_size)
403 {
404  MOVMuxContext *mov = s->priv_data;
405  MOVTrack *trk = &mov->tracks[track_index];
406  AVFormatContext *rtp_ctx = trk->rtp_ctx;
407  uint8_t *buf = NULL;
408  int size;
409  AVIOContext *hintbuf = NULL;
410  AVPacket hint_pkt;
411  int ret = 0, count;
412 
413  if (!rtp_ctx)
414  return AVERROR(ENOENT);
415  if (!rtp_ctx->pb)
416  return AVERROR(ENOMEM);
417 
418  if (sample_data)
419  sample_queue_push(&trk->sample_queue, sample_data, sample_size, sample);
420  else
421  sample_queue_push(&trk->sample_queue, pkt->data, pkt->size, sample);
422 
423  /* Feed the packet to the RTP muxer */
424  ff_write_chained(rtp_ctx, 0, pkt, s);
425 
426  /* Fetch the output from the RTP muxer, open a new output buffer
427  * for next time. */
428  size = avio_close_dyn_buf(rtp_ctx->pb, &buf);
429  if ((ret = ffio_open_dyn_packet_buf(&rtp_ctx->pb,
430  RTP_MAX_PACKET_SIZE)) < 0)
431  goto done;
432 
433  if (size <= 0)
434  goto done;
435 
436  /* Open a buffer for writing the hint */
437  if ((ret = avio_open_dyn_buf(&hintbuf)) < 0)
438  goto done;
439  av_init_packet(&hint_pkt);
440  count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
441  av_freep(&buf);
442 
443  /* Write the hint data into the hint track */
444  hint_pkt.size = size = avio_close_dyn_buf(hintbuf, &buf);
445  hint_pkt.data = buf;
446  hint_pkt.pts = hint_pkt.dts;
447  hint_pkt.stream_index = track_index;
448  if (pkt->flags & AV_PKT_FLAG_KEY)
449  hint_pkt.flags |= AV_PKT_FLAG_KEY;
450  if (count > 0)
451  ff_mov_write_packet(s, &hint_pkt);
452 done:
453  av_free(buf);
455  return ret;
456 }
457 
459 {
460  AVFormatContext *rtp_ctx = track->rtp_ctx;
461  uint8_t *ptr;
462 
463  av_freep(&track->enc);
465  if (!rtp_ctx)
466  return;
467  if (rtp_ctx->pb) {
468  av_write_trailer(rtp_ctx);
469  avio_close_dyn_buf(rtp_ctx->pb, &ptr);
470  av_free(ptr);
471  }
472  avformat_free_context(rtp_ctx);
473 }