libavformat/movenchint.c

   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
  40     track->enc = avcodec_alloc_context3(NULL);
  41     if (!track->enc)
  42         goto fail;
  43     track->enc->codec_type = AVMEDIA_TYPE_DATA;
  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:
  59     av_log(s, AV_LOG_WARNING,
  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
  67 /**
  68  * Remove the first sample from the sample queue.
  69  */
  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
  80 /**
  81  * Empty the sample queue, releasing all memory.
  82  */
  83 static void sample_queue_free(HintSampleQueue *queue)
  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
  94 /**
  95  * Add a reference to the sample data to the sample queue. The data is
  96  * not copied. sample_queue_retain should be called before pkt->data
  97  * is reused/freed.
  98  */
  99 static void sample_queue_push(HintSampleQueue *queue, uint8_t *data, int size,
 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         HintSample* samples;
 108         queue->size += 10;
 109         samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);
 110         if (!samples)
 111             return;
 112         queue->samples = samples;
 113     }
 114     queue->samples[queue->len].data = data;
 115     queue->samples[queue->len].size = size;
 116     queue->samples[queue->len].sample_number = sample;
 117     queue->samples[queue->len].offset = 0;
 118     queue->samples[queue->len].own_data = 0;
 119     queue->len++;
 120 }
 121
 122 /**
 123  * Make local copies of all referenced sample data in the queue.
 124  */
 125 static void sample_queue_retain(HintSampleQueue *queue)
 126 {
 127     int i;
 128     for (i = 0; i < queue->len; ) {
 129         HintSample *sample = &queue->samples[i];
 130         if (!sample->own_data) {
 131             uint8_t* ptr = av_malloc(sample->size);
 132             if (!ptr) {
 133                 /* Unable to allocate memory for this one, remove it */
 134                 memmove(queue->samples + i, queue->samples + i + 1,
 135                         sizeof(HintSample)*(queue->len - i - 1));
 136                 queue->len--;
 137                 continue;
 138             }
 139             memcpy(ptr, sample->data, sample->size);
 140             sample->data = ptr;
 141             sample->own_data = 1;
 142         }
 143         i++;
 144     }
 145 }
 146
 147 /**
 148  * Find matches of needle[n_pos ->] within haystack. If a sufficiently
 149  * large match is found, matching bytes before n_pos are included
 150  * in the match, too (within the limits of the arrays).
 151  *
 152  * @param haystack buffer that may contain parts of needle
 153  * @param h_len length of the haystack buffer
 154  * @param needle buffer containing source data that have been used to
 155  *               construct haystack
 156  * @param n_pos start position in needle used for looking for matches
 157  * @param n_len length of the needle buffer
 158  * @param match_h_offset_ptr offset of the first matching byte within haystack
 159  * @param match_n_offset_ptr offset of the first matching byte within needle
 160  * @param match_len_ptr length of the matched segment
 161  * @return 0 if a match was found, < 0 if no match was found
 162  */
 163 static int match_segments(const uint8_t *haystack, int h_len,
 164                           const uint8_t *needle, int n_pos, int n_len,
 165                           int *match_h_offset_ptr, int *match_n_offset_ptr,
 166                           int *match_len_ptr)
 167 {
 168     int h_pos;
 169     for (h_pos = 0; h_pos < h_len; h_pos++) {
 170         int match_len = 0;
 171         int match_h_pos, match_n_pos;
 172
 173         /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
 174         while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
 175                needle[n_pos + match_len] == haystack[h_pos + match_len])
 176             match_len++;
 177         if (match_len <= 8)
 178             continue;
 179
 180         /* If a sufficiently large match was found, try to expand
 181          * the matched segment backwards. */
 182         match_h_pos = h_pos;
 183         match_n_pos = n_pos;
 184         while (match_n_pos > 0 && match_h_pos > 0 &&
 185                needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
 186             match_n_pos--;
 187             match_h_pos--;
 188             match_len++;
 189         }
 190         if (match_len <= 14)
 191             continue;
 192         *match_h_offset_ptr = match_h_pos;
 193         *match_n_offset_ptr = match_n_pos;
 194         *match_len_ptr = match_len;
 195         return 0;
 196     }
 197     return -1;
 198 }
 199
 200 /**
 201  * Look for segments in samples in the sample queue matching the data
 202  * in ptr. Samples not matching are removed from the queue. If a match
 203  * is found, the next time it will look for matches starting from the
 204  * end of the previous matched segment.
 205  *
 206  * @param data data to find matches for in the sample queue
 207  * @param len length of the data buffer
 208  * @param queue samples used for looking for matching segments
 209  * @param pos the offset in data of the matched segment
 210  * @param match_sample the number of the sample that contained the match
 211  * @param match_offset the offset of the matched segment within the sample
 212  * @param match_len the length of the matched segment
 213  * @return 0 if a match was found, < 0 if no match was found
 214  */
 215 static int find_sample_match(const uint8_t *data, int len,
 216                              HintSampleQueue *queue, int *pos,
 217                              int *match_sample, int *match_offset,
 218                              int *match_len)
 219 {
 220     while (queue->len > 0) {
 221         HintSample *sample = &queue->samples[0];
 222         /* If looking for matches in a new sample, skip the first 5 bytes,
 223          * since they often may be modified/removed in the output packet. */
 224         if (sample->offset == 0 && sample->size > 5)
 225             sample->offset = 5;
 226
 227         if (match_segments(data, len, sample->data, sample->offset,
 228                            sample->size, pos, match_offset, match_len) == 0) {
 229             *match_sample = sample->sample_number;
 230             /* Next time, look for matches at this offset, with a little
 231              * margin to this match. */
 232             sample->offset = *match_offset + *match_len + 5;
 233             if (sample->offset + 10 >= sample->size)
 234                 sample_queue_pop(queue); /* Not enough useful data left */
 235             return 0;
 236         }
 237
 238         if (sample->offset < 10 && sample->size > 20) {
 239             /* No match found from the start of the sample,
 240              * try from the middle of the sample instead. */
 241             sample->offset = sample->size/2;
 242         } else {
 243             /* No match for this sample, remove it */
 244             sample_queue_pop(queue);
 245         }
 246     }
 247     return -1;
 248 }
 249
 250 static void output_immediate(const uint8_t *data, int size,
 251                              AVIOContext *out, int *entries)
 252 {
 253     while (size > 0) {
 254         int len = size;
 255         if (len > 14)
 256             len = 14;
 257         avio_w8(out, 1); /* immediate constructor */
 258         avio_w8(out, len); /* amount of valid data */
 259         avio_write(out, data, len);
 260         data += len;
 261         size -= len;
 262
 263         for (; len < 14; len++)
 264             avio_w8(out, 0);
 265
 266         (*entries)++;
 267     }
 268 }
 269
 270 static void output_match(AVIOContext *out, int match_sample,
 271                          int match_offset, int match_len, int *entries)
 272 {
 273     avio_w8(out, 2); /* sample constructor */
 274     avio_w8(out, 0); /* track reference */
 275     avio_wb16(out, match_len);
 276     avio_wb32(out, match_sample);
 277     avio_wb32(out, match_offset);
 278     avio_wb16(out, 1); /* bytes per block */
 279     avio_wb16(out, 1); /* samples per block */
 280     (*entries)++;
 281 }
 282
 283 static void describe_payload(const uint8_t *data, int size,
 284                              AVIOContext *out, int *entries,
 285                              HintSampleQueue *queue)
 286 {
 287     /* Describe the payload using different constructors */
 288     while (size > 0) {
 289         int match_sample, match_offset, match_len, pos;
 290         if (find_sample_match(data, size, queue, &pos, &match_sample,
 291                               &match_offset, &match_len) < 0)
 292             break;
 293         output_immediate(data, pos, out, entries);
 294         data += pos;
 295         size -= pos;
 296         output_match(out, match_sample, match_offset, match_len, entries);
 297         data += match_len;
 298         size -= match_len;
 299     }
 300     output_immediate(data, size, out, entries);
 301 }
 302
 303 /**
 304  * Write an RTP hint (that may contain one or more RTP packets)
 305  * for the packets in data. data contains one or more packets with a
 306  * BE32 size header.
 307  *
 308  * @param out buffer where the hints are written
 309  * @param data buffer containing RTP packets
 310  * @param size the size of the data buffer
 311  * @param trk the MOVTrack for the hint track
 312  * @param pts pointer where the timestamp for the written RTP hint is stored
 313  * @return the number of RTP packets in the written hint
 314  */
 315 static int write_hint_packets(AVIOContext *out, const uint8_t *data,
 316                               int size, MOVTrack *trk, int64_t *pts)
 317 {
 318     int64_t curpos;
 319     int64_t count_pos, entries_pos;
 320     int count = 0, entries;
 321
 322     count_pos = avio_tell(out);
 323     /* RTPsample header */
 324     avio_wb16(out, 0); /* packet count */
 325     avio_wb16(out, 0); /* reserved */
 326
 327     while (size > 4) {
 328         uint32_t packet_len = AV_RB32(data);
 329         uint16_t seq;
 330         uint32_t ts;
 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         trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
 354         trk->prev_rtp_ts = ts;
 355         if (*pts == AV_NOPTS_VALUE)
 356             *pts = trk->cur_rtp_ts_unwrapped;
 357
 358         count++;
 359         /* RTPpacket header */
 360         avio_wb32(out, 0); /* relative_time */
 361         avio_write(out, data, 2); /* RTP header */
 362         avio_wb16(out, seq); /* RTPsequenceseed */
 363         avio_wb16(out, 0); /* reserved + flags */
 364         entries_pos = avio_tell(out);
 365         avio_wb16(out, 0); /* entry count */
 366
 367         data += 12;
 368         size -= 12;
 369         packet_len -= 12;
 370
 371         entries = 0;
 372         /* Write one or more constructors describing the payload data */
 373         describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
 374         data += packet_len;
 375         size -= packet_len;
 376
 377         curpos = avio_tell(out);
 378         avio_seek(out, entries_pos, SEEK_SET);
 379         avio_wb16(out, entries);
 380         avio_seek(out, curpos, SEEK_SET);
 381     }
 382
 383     curpos = avio_tell(out);
 384     avio_seek(out, count_pos, SEEK_SET);
 385     avio_wb16(out, count);
 386     avio_seek(out, curpos, SEEK_SET);
 387     return count;
 388 }
 389
 390 int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
 391                              int track_index, int sample,
 392                              uint8_t *sample_data, int sample_size)
 393 {
 394     MOVMuxContext *mov = s->priv_data;
 395     MOVTrack *trk = &mov->tracks[track_index];
 396     AVFormatContext *rtp_ctx = trk->rtp_ctx;
 397     uint8_t *buf = NULL;
 398     int size;
 399     AVIOContext *hintbuf = NULL;
 400     AVPacket hint_pkt;
 401     int ret = 0, count;
 402
 403     if (!rtp_ctx)
 404         return AVERROR(ENOENT);
 405     if (!rtp_ctx->pb)
 406         return AVERROR(ENOMEM);
 407
 408     if (sample_data)
 409         sample_queue_push(&trk->sample_queue, sample_data, sample_size, sample);
 410     else
 411         sample_queue_push(&trk->sample_queue, pkt->data, pkt->size, sample);
 412
 413     /* Feed the packet to the RTP muxer */
 414     ff_write_chained(rtp_ctx, 0, pkt, s);
 415
 416     /* Fetch the output from the RTP muxer, open a new output buffer
 417      * for next time. */
 418     size = avio_close_dyn_buf(rtp_ctx->pb, &buf);
 419     if ((ret = ffio_open_dyn_packet_buf(&rtp_ctx->pb,
 420                                        RTP_MAX_PACKET_SIZE)) < 0)
 421         goto done;
 422
 423     if (size <= 0)
 424         goto done;
 425
 426     /* Open a buffer for writing the hint */
 427     if ((ret = avio_open_dyn_buf(&hintbuf)) < 0)
 428         goto done;
 429     av_init_packet(&hint_pkt);
 430     count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
 431     av_freep(&buf);
 432
 433     /* Write the hint data into the hint track */
 434     hint_pkt.size = size = avio_close_dyn_buf(hintbuf, &buf);
 435     hint_pkt.data = buf;
 436     hint_pkt.pts  = hint_pkt.dts;
 437     hint_pkt.stream_index = track_index;
 438     if (pkt->flags & AV_PKT_FLAG_KEY)
 439         hint_pkt.flags |= AV_PKT_FLAG_KEY;
 440     if (count > 0)
 441         ff_mov_write_packet(s, &hint_pkt);
 442 done:
 443     av_free(buf);
 444     sample_queue_retain(&trk->sample_queue);
 445     return ret;
 446 }
 447
 448 void ff_mov_close_hinting(MOVTrack *track) {
 449     AVFormatContext* rtp_ctx = track->rtp_ctx;
 450     uint8_t *ptr;
 451
 452     av_freep(&track->enc);
 453     sample_queue_free(&track->sample_queue);
 454     if (!rtp_ctx)
 455         return;
 456     if (rtp_ctx->pb) {
 457         av_write_trailer(rtp_ctx);
 458         avio_close_dyn_buf(rtp_ctx->pb, &ptr);
 459         av_free(ptr);
 460     }
 461     avformat_free_context(rtp_ctx);
 462 }