libavformat/prompeg.c

   1 /*
   2  * Pro-MPEG Code of Practice #3 Release 2 FEC
   3  * Copyright (c) 2016 Mobibase, France (http://www.mobibase.com)
   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  * Pro-MPEG Code of Practice #3 Release 2 FEC protocol
  25  * @author Vlad Tarca <vlad.tarca@gmail.com>
  26  */
  27
  28 /*
  29  * Reminder:
  30
  31  [RFC 2733] FEC Packet Structure
  32
  33    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  34    |                         RTP Header                            |
  35    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  36    |                         FEC Header                            |
  37    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  38    |                         FEC Payload                           |
  39    |                                                               |
  40    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  41
  42
  43  [RFC 3550] RTP header
  44
  45     0                   1                   2                   3
  46     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  47    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  48    |V=2|P|X|  CC   |M|     PT      |       sequence number         |
  49    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  50    |                           timestamp                           |
  51    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  52    |           synchronization source (SSRC) identifier            |
  53    +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
  54    |            contributing source (CSRC) identifiers             |
  55    |                             ....                              |
  56    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  57
  58  [RFC 3550] RTP header extension (after CSRC)
  59
  60     0                   1                   2                   3
  61     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  62    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  63    |      defined by profile       |           length              |
  64    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  65    |                        header extension                       |
  66    |                             ....                              |
  67    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  68
  69  [Pro-MPEG COP3] FEC Header
  70
  71    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  72    |      SNBase low bits          |        length recovery        |
  73    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  74    |E| PT recovery |                 mask                          |
  75    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  76    |                          TS recovery                          |
  77    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  78    |X|D|type |index|    offset     |      NA       |SNBase ext bits|
  79    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  80
  81  */
  82
  83 #include "libavutil/avstring.h"
  84 #include "libavutil/intreadwrite.h"
  85 #include "libavutil/opt.h"
  86 #include "libavutil/parseutils.h"
  87 #include "libavutil/random_seed.h"
  88 #include "avformat.h"
  89 #include "config.h"
  90 #include "url.h"
  91
  92 #define PROMPEG_RTP_PT 0x60
  93 #define PROMPEG_FEC_COL 0x0
  94 #define PROMPEG_FEC_ROW 0x1
  95
  96 typedef struct PrompegFec {
  97     uint16_t sn;
  98     uint32_t ts;
  99     uint8_t *bitstring;
 100 } PrompegFec;
 101
 102 typedef struct PrompegContext {
 103     const AVClass *class;
 104     URLContext *fec_col_hd, *fec_row_hd;
 105     PrompegFec **fec_arr, **fec_col_tmp, **fec_col, *fec_row;
 106     int ttl;
 107     uint8_t l, d;
 108     uint8_t *rtp_buf;
 109     uint16_t rtp_col_sn, rtp_row_sn;
 110     uint16_t length_recovery;
 111     int packet_size;
 112     int packet_idx, packet_idx_max;
 113     int fec_arr_len;
 114     int bitstring_size;
 115     int rtp_buf_size;
 116     int init;
 117     int first;
 118 } PrompegContext;
 119
 120 #define OFFSET(x) offsetof(PrompegContext, x)
 121 #define E AV_OPT_FLAG_ENCODING_PARAM
 122
 123 static const AVOption options[] = {
 124     { "ttl",   "Time to live (in milliseconds, multicast only)", OFFSET(ttl), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, .flags = E },
 125     { "l", "FEC L", OFFSET(l), AV_OPT_TYPE_INT, { .i64 =  5 }, 4, 20, .flags = E },
 126     { "d", "FEC D", OFFSET(d), AV_OPT_TYPE_INT, { .i64 =  5 }, 4, 20, .flags = E },
 127     { NULL }
 128 };
 129
 130 static const AVClass prompeg_class = {
 131     .class_name = "prompeg",
 132     .item_name  = av_default_item_name,
 133     .option     = options,
 134     .version    = LIBAVUTIL_VERSION_INT,
 135 };
 136
 137 static void xor_fast(const uint8_t *in1, const uint8_t *in2, uint8_t *out, int size) {
 138     int i, n, s;
 139
 140 #if HAVE_FAST_64BIT
 141     uint64_t v1, v2;
 142
 143     n = size / sizeof (uint64_t);
 144     s = n * sizeof (uint64_t);
 145
 146     for (i = 0; i < n; i++) {
 147         v1 = AV_RN64A(in1);
 148         v2 = AV_RN64A(in2);
 149         AV_WN64A(out, v1 ^ v2);
 150         in1 += 8;
 151         in2 += 8;
 152         out += 8;
 153     }
 154 #else
 155     uint32_t v1, v2;
 156
 157     n = size / sizeof (uint32_t);
 158     s = n * sizeof (uint32_t);
 159
 160     for (i = 0; i < n; i++) {
 161         v1 = AV_RN32A(in1);
 162         v2 = AV_RN32A(in2);
 163         AV_WN32A(out, v1 ^ v2);
 164         in1 += 4;
 165         in2 += 4;
 166         out += 4;
 167     }
 168 #endif
 169
 170     n = size - s;
 171
 172     for (i = 0; i < n; i++) {
 173         out[i] = in1[i] ^ in2[i];
 174     }
 175 }
 176
 177 static int prompeg_create_bitstring(URLContext *h, const uint8_t *buf, int size,
 178         uint8_t **bitstring) {
 179     PrompegContext *s = h->priv_data;
 180     uint8_t *b;
 181
 182     if (size < 12 || (buf[0] & 0xc0) != 0x80 || (buf[1] & 0x7f) != 0x21) {
 183         av_log(h, AV_LOG_ERROR, "Unsupported stream format (expected MPEG-TS over RTP)\n");
 184         return AVERROR(EINVAL);
 185     }
 186     if (size != s->packet_size) {
 187         av_log(h, AV_LOG_ERROR, "The RTP packet size must be constant (set pkt_size)\n");
 188         return AVERROR(EINVAL);
 189     }
 190
 191     *bitstring = av_malloc(s->bitstring_size);
 192     if (!*bitstring) {
 193         av_log(h, AV_LOG_ERROR, "Failed to allocate the bitstring buffer\n");
 194         return AVERROR(ENOMEM);
 195     }
 196     b = *bitstring;
 197
 198     // P, X, CC
 199     b[0] = buf[0] & 0x3f;
 200     // M, PT
 201     b[1] = buf[1];
 202     // Timestamp
 203     b[2] = buf[4];
 204     b[3] = buf[5];
 205     b[4] = buf[6];
 206     b[5] = buf[7];
 207     /*
 208      * length_recovery: the unsigned network-ordered sum of lengths of CSRC,
 209      * padding, extension and media payload
 210      */
 211     AV_WB16(b + 6, s->length_recovery);
 212     // Payload
 213     memcpy(b + 8, buf + 12, s->length_recovery);
 214
 215     return 0;
 216 }
 217
 218 static int prompeg_write_fec(URLContext *h, PrompegFec *fec, uint8_t type) {
 219     PrompegContext *s = h->priv_data;
 220     URLContext *hd;
 221     uint8_t *buf = s->rtp_buf; // zero-filled
 222     uint8_t *b = fec->bitstring;
 223     uint16_t sn;
 224     int ret;
 225
 226     sn = type == PROMPEG_FEC_COL ? ++s->rtp_col_sn : ++s->rtp_row_sn;
 227
 228     // V, P, X, CC
 229     buf[0] = 0x80 | (b[0] & 0x3f);
 230     // M, PT
 231     buf[1] = (b[1] & 0x80) | PROMPEG_RTP_PT;
 232     // SN
 233     AV_WB16(buf + 2, sn);
 234     // TS
 235     AV_WB32(buf + 4, fec->ts);
 236     // CSRC=0
 237     //AV_WB32(buf + 8, 0);
 238     // SNBase low bits
 239     AV_WB16(buf + 12, fec->sn);
 240     // Length recovery
 241     buf[14] = b[6];
 242     buf[15] = b[7];
 243     // E=1, PT recovery
 244     buf[16] = 0x80 | b[1];
 245     // Mask=0
 246     //buf[17] = 0x0;
 247     //buf[18] = 0x0;
 248     //buf[19] = 0x0;
 249     // TS recovery
 250     buf[20] = b[2];
 251     buf[21] = b[3];
 252     buf[22] = b[4];
 253     buf[23] = b[5];
 254     // X=0, D, type=0, index=0
 255     buf[24] = type == PROMPEG_FEC_COL ? 0x0 : 0x40;
 256     // offset
 257     buf[25] = type == PROMPEG_FEC_COL ? s->l : 0x1;
 258     // NA
 259     buf[26] = type == PROMPEG_FEC_COL ? s->d : s->l;
 260     // SNBase ext bits=0
 261     //buf[27] = 0x0;
 262     // Payload
 263     memcpy(buf + 28, b + 8, s->length_recovery);
 264
 265     hd = type == PROMPEG_FEC_COL ? s->fec_col_hd : s->fec_row_hd;
 266     ret = ffurl_write(hd, buf, s->rtp_buf_size);
 267     return ret;
 268 }
 269
 270 static int prompeg_open(URLContext *h, const char *uri, int flags) {
 271     PrompegContext *s = h->priv_data;
 272     AVDictionary *udp_opts = NULL;
 273     int rtp_port;
 274     char hostname[256];
 275     char buf[1024];
 276
 277     s->fec_col_hd = NULL;
 278     s->fec_row_hd = NULL;
 279
 280     if (s->l * s->d > 100) {
 281         av_log(h, AV_LOG_ERROR, "L * D must be <= 100\n");
 282         return AVERROR(EINVAL);
 283     }
 284
 285     av_url_split(NULL, 0, NULL, 0, hostname, sizeof (hostname), &rtp_port,
 286             NULL, 0, uri);
 287
 288     if (rtp_port < 1 || rtp_port > UINT16_MAX - 4) {
 289         av_log(h, AV_LOG_ERROR, "Invalid RTP base port %d\n", rtp_port);
 290         return AVERROR(EINVAL);
 291     }
 292
 293     if (s->ttl > 0) {
 294         av_dict_set_int(&udp_opts, "ttl", s->ttl, 0);
 295     }
 296
 297     ff_url_join(buf, sizeof (buf), "udp", NULL, hostname, rtp_port + 2, NULL);
 298     if (ffurl_open_whitelist(&s->fec_col_hd, buf, flags, &h->interrupt_callback,
 299             &udp_opts, h->protocol_whitelist, h->protocol_blacklist, h) < 0)
 300         goto fail;
 301     ff_url_join(buf, sizeof (buf), "udp", NULL, hostname, rtp_port + 4, NULL);
 302     if (ffurl_open_whitelist(&s->fec_row_hd, buf, flags, &h->interrupt_callback,
 303             &udp_opts, h->protocol_whitelist, h->protocol_blacklist, h) < 0)
 304         goto fail;
 305
 306     h->max_packet_size = s->fec_col_hd->max_packet_size;
 307     s->init = 1;
 308
 309     av_dict_free(&udp_opts);
 310     av_log(h, AV_LOG_INFO, "ProMPEG CoP#3-R2 FEC L=%d D=%d\n", s->l, s->d);
 311     return 0;
 312
 313 fail:
 314     ffurl_closep(&s->fec_col_hd);
 315     ffurl_closep(&s->fec_row_hd);
 316     av_dict_free(&udp_opts);
 317     return AVERROR(EIO);
 318 }
 319
 320 static int prompeg_init(URLContext *h, const uint8_t *buf, int size) {
 321     PrompegContext *s = h->priv_data;
 322     uint32_t seed;
 323     int i;
 324
 325     s->fec_arr = NULL;
 326     s->rtp_buf = NULL;
 327
 328     if (size < 12 || size > UINT16_MAX + 12) {
 329         av_log(h, AV_LOG_ERROR, "Invalid RTP packet size\n");
 330         return AVERROR_INVALIDDATA;
 331     }
 332
 333     s->packet_idx = 0;
 334     s->packet_idx_max = s->l * s->d;
 335     s->packet_size = size;
 336     s->length_recovery = size - 12;
 337     s->rtp_buf_size = 28 + s->length_recovery; // 12 + 16: RTP + FEC headers
 338     s->bitstring_size = 8 + s->length_recovery; // 8: P, X, CC, M, PT, SN, TS
 339     s->fec_arr_len = 1 + 2 * s->l; // row + column tmp + column out
 340
 341     if (h->flags & AVFMT_FLAG_BITEXACT) {
 342         s->rtp_col_sn = 0;
 343         s->rtp_row_sn = 0;
 344     } else {
 345         seed = av_get_random_seed();
 346         s->rtp_col_sn = seed & 0x0fff;
 347         s->rtp_row_sn = (seed >> 16) & 0x0fff;
 348     }
 349
 350     s->fec_arr = av_malloc_array(s->fec_arr_len, sizeof (PrompegFec*));
 351     if (!s->fec_arr) {
 352         goto fail;
 353     }
 354     for (i = 0; i < s->fec_arr_len; i++) {
 355         s->fec_arr[i] = av_malloc(sizeof (PrompegFec));
 356         if (!s->fec_arr[i]) {
 357             goto fail;
 358         }
 359         s->fec_arr[i]->bitstring = av_malloc_array(s->bitstring_size, sizeof (uint8_t));
 360         if (!s->fec_arr[i]->bitstring) {
 361             av_freep(&s->fec_arr[i]);
 362             goto fail;
 363         }
 364     }
 365     s->fec_row = *s->fec_arr;
 366     s->fec_col = s->fec_arr + 1;
 367     s->fec_col_tmp = s->fec_arr + 1 + s->l;
 368
 369     s->rtp_buf = av_malloc_array(s->rtp_buf_size, sizeof (uint8_t));
 370     if (!s->rtp_buf) {
 371         goto fail;
 372     }
 373     memset(s->rtp_buf, 0, s->rtp_buf_size);
 374
 375     s->init = 0;
 376     s->first = 1;
 377
 378     return 0;
 379
 380 fail:
 381     av_log(h, AV_LOG_ERROR, "Failed to allocate the FEC buffer\n");
 382     return AVERROR(ENOMEM);
 383 }
 384
 385 static int prompeg_write(URLContext *h, const uint8_t *buf, int size) {
 386     PrompegContext *s = h->priv_data;
 387     PrompegFec *fec_tmp;
 388     uint8_t *bitstring = NULL;
 389     int col_idx, col_out_idx, row_idx;
 390     int ret = 0;
 391
 392     if (s->init && ((ret = prompeg_init(h, buf, size)) < 0))
 393         goto end;
 394
 395     if ((ret = prompeg_create_bitstring(h, buf, size, &bitstring)) < 0)
 396         goto end;
 397
 398     col_idx = s->packet_idx % s->l;
 399     row_idx = s->packet_idx / s->l % s->d;
 400
 401     // FEC' (row) send block-aligned, xor
 402     if (col_idx == 0) {
 403         if (!s->first || s->packet_idx > 0) {
 404             if ((ret = prompeg_write_fec(h, s->fec_row, PROMPEG_FEC_ROW)) < 0)
 405                 goto end;
 406         }
 407         memcpy(s->fec_row->bitstring, bitstring, s->bitstring_size);
 408         s->fec_row->sn = AV_RB16(buf + 2);
 409         s->fec_row->ts = AV_RB32(buf + 4);
 410     } else {
 411         xor_fast(s->fec_row->bitstring, bitstring, s->fec_row->bitstring,
 412                 s->bitstring_size);
 413     }
 414
 415     // FEC (column) xor
 416     if (row_idx == 0) {
 417         if (!s->first) {
 418             // swap fec_col and fec_col_tmp
 419             fec_tmp = s->fec_col[col_idx];
 420             s->fec_col[col_idx] = s->fec_col_tmp[col_idx];
 421             s->fec_col_tmp[col_idx] = fec_tmp;
 422         }
 423         memcpy(s->fec_col_tmp[col_idx]->bitstring, bitstring, s->bitstring_size);
 424         s->fec_col_tmp[col_idx]->sn = AV_RB16(buf + 2);
 425         s->fec_col_tmp[col_idx]->ts = AV_RB32(buf + 4);
 426     } else {
 427         xor_fast(s->fec_col_tmp[col_idx]->bitstring, bitstring,
 428                 s->fec_col_tmp[col_idx]->bitstring, s->bitstring_size);
 429     }
 430
 431     // FEC (column) send block-aligned
 432     if (!s->first && s->packet_idx % s->d == 0) {
 433         col_out_idx = s->packet_idx / s->d;
 434         if ((ret = prompeg_write_fec(h, s->fec_col[col_out_idx], PROMPEG_FEC_COL)) < 0)
 435             goto end;
 436     }
 437
 438     if (++s->packet_idx >= s->packet_idx_max) {
 439         s->packet_idx = 0;
 440         if (s->first)
 441             s->first = 0;
 442     }
 443
 444     ret = size;
 445
 446 end:
 447     av_free(bitstring);
 448     return ret;
 449 }
 450
 451 static int prompeg_close(URLContext *h) {
 452     PrompegContext *s = h->priv_data;
 453     int i;
 454
 455     ffurl_closep(&s->fec_col_hd);
 456     ffurl_closep(&s->fec_row_hd);
 457
 458     if (s->fec_arr) {
 459         for (i = 0; i < s->fec_arr_len; i++) {
 460             av_free(s->fec_arr[i]->bitstring);
 461             av_freep(&s->fec_arr[i]);
 462         }
 463         av_freep(&s->fec_arr);
 464     }
 465     av_freep(&s->rtp_buf);
 466
 467     return 0;
 468 }
 469
 470 const URLProtocol ff_prompeg_protocol = {
 471     .name                      = "prompeg",
 472     .url_open                  = prompeg_open,
 473     .url_write                 = prompeg_write,
 474     .url_close                 = prompeg_close,
 475     .priv_data_size            = sizeof(PrompegContext),
 476     .flags                     = URL_PROTOCOL_FLAG_NETWORK,
 477     .priv_data_class           = &prompeg_class,
 478 };