2 * Pro-MPEG Code of Practice #3 Release 2 FEC
3 * Copyright (c) 2016 Mobibase, France (http://www.mobibase.com)
5 * This file is part of FFmpeg.
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.
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.
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
24 * Pro-MPEG Code of Practice #3 Release 2 FEC protocol
25 * @author Vlad Tarca <vlad.tarca@gmail.com>
31 [RFC 2733] FEC Packet Structure
33 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
35 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
37 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
40 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
51 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
52 | synchronization source (SSRC) identifier |
53 +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
54 | contributing source (CSRC) identifiers |
56 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
58 [RFC 3550] RTP header extension (after CSRC)
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
67 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
69 [Pro-MPEG COP3] FEC Header
71 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
72 | SNBase low bits | length recovery |
73 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
74 |E| PT recovery | mask |
75 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
77 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
78 |X|D|type |index| offset | NA |SNBase ext bits|
79 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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"
92 #define PROMPEG_RTP_PT 0x60
93 #define PROMPEG_FEC_COL 0x0
94 #define PROMPEG_FEC_ROW 0x1
96 typedef struct PrompegFec {
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;
109 uint16_t rtp_col_sn, rtp_row_sn;
110 uint16_t length_recovery;
112 int packet_idx, packet_idx_max;
120 #define OFFSET(x) offsetof(PrompegContext, x)
121 #define E AV_OPT_FLAG_ENCODING_PARAM
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 },
130 static const AVClass prompeg_class = {
131 .class_name = "prompeg",
132 .item_name = av_default_item_name,
134 .version = LIBAVUTIL_VERSION_INT,
137 static void xor_fast(const uint8_t *in1, const uint8_t *in2, uint8_t *out, int size) {
143 n = size / sizeof (uint64_t);
144 s = n * sizeof (uint64_t);
146 for (i = 0; i < n; i++) {
149 AV_WN64A(out, v1 ^ v2);
157 n = size / sizeof (uint32_t);
158 s = n * sizeof (uint32_t);
160 for (i = 0; i < n; i++) {
163 AV_WN32A(out, v1 ^ v2);
172 for (i = 0; i < n; i++) {
173 out[i] = in1[i] ^ in2[i];
177 static int prompeg_create_bitstring(URLContext *h, const uint8_t *buf, int size,
178 uint8_t **bitstring) {
179 PrompegContext *s = h->priv_data;
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);
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);
191 *bitstring = av_malloc(s->bitstring_size);
193 av_log(h, AV_LOG_ERROR, "Failed to allocate the bitstring buffer\n");
194 return AVERROR(ENOMEM);
199 b[0] = buf[0] & 0x3f;
208 * length_recovery: the unsigned network-ordered sum of lengths of CSRC,
209 * padding, extension and media payload
211 AV_WB16(b + 6, s->length_recovery);
213 memcpy(b + 8, buf + 12, s->length_recovery);
218 static int prompeg_write_fec(URLContext *h, PrompegFec *fec, uint8_t type) {
219 PrompegContext *s = h->priv_data;
221 uint8_t *buf = s->rtp_buf; // zero-filled
222 uint8_t *b = fec->bitstring;
226 sn = type == PROMPEG_FEC_COL ? ++s->rtp_col_sn : ++s->rtp_row_sn;
229 buf[0] = 0x80 | (b[0] & 0x3f);
231 buf[1] = (b[1] & 0x80) | PROMPEG_RTP_PT;
233 AV_WB16(buf + 2, sn);
235 AV_WB32(buf + 4, fec->ts);
237 //AV_WB32(buf + 8, 0);
239 AV_WB16(buf + 12, fec->sn);
244 buf[16] = 0x80 | b[1];
254 // X=0, D, type=0, index=0
255 buf[24] = type == PROMPEG_FEC_COL ? 0x0 : 0x40;
257 buf[25] = type == PROMPEG_FEC_COL ? s->l : 0x1;
259 buf[26] = type == PROMPEG_FEC_COL ? s->d : s->l;
263 memcpy(buf + 28, b + 8, s->length_recovery);
265 hd = type == PROMPEG_FEC_COL ? s->fec_col_hd : s->fec_row_hd;
266 ret = ffurl_write(hd, buf, s->rtp_buf_size);
270 static int prompeg_open(URLContext *h, const char *uri, int flags) {
271 PrompegContext *s = h->priv_data;
272 AVDictionary *udp_opts = NULL;
277 s->fec_col_hd = NULL;
278 s->fec_row_hd = NULL;
280 if (s->l * s->d > 100) {
281 av_log(h, AV_LOG_ERROR, "L * D must be <= 100\n");
282 return AVERROR(EINVAL);
285 av_url_split(NULL, 0, NULL, 0, hostname, sizeof (hostname), &rtp_port,
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);
294 snprintf(buf, sizeof (buf), "%d", s->ttl);
295 av_dict_set(&udp_opts, "ttl", buf, 0);
298 ff_url_join(buf, sizeof (buf), "udp", NULL, hostname, rtp_port + 2, NULL);
299 if (ffurl_open_whitelist(&s->fec_col_hd, buf, flags, &h->interrupt_callback,
300 &udp_opts, h->protocol_whitelist, h->protocol_blacklist, h) < 0)
302 ff_url_join(buf, sizeof (buf), "udp", NULL, hostname, rtp_port + 4, NULL);
303 if (ffurl_open_whitelist(&s->fec_row_hd, buf, flags, &h->interrupt_callback,
304 &udp_opts, h->protocol_whitelist, h->protocol_blacklist, h) < 0)
307 h->max_packet_size = s->fec_col_hd->max_packet_size;
310 av_dict_free(&udp_opts);
311 av_log(h, AV_LOG_INFO, "ProMPEG CoP#3-R2 FEC L=%d D=%d\n", s->l, s->d);
315 ffurl_closep(&s->fec_col_hd);
316 ffurl_closep(&s->fec_row_hd);
317 av_dict_free(&udp_opts);
321 static int prompeg_init(URLContext *h, const uint8_t *buf, int size) {
322 PrompegContext *s = h->priv_data;
329 if (size < 12 || size > UINT16_MAX + 12) {
330 av_log(h, AV_LOG_ERROR, "Invalid RTP packet size\n");
331 return AVERROR_INVALIDDATA;
335 s->packet_idx_max = s->l * s->d;
336 s->packet_size = size;
337 s->length_recovery = size - 12;
338 s->rtp_buf_size = 28 + s->length_recovery; // 12 + 16: RTP + FEC headers
339 s->bitstring_size = 8 + s->length_recovery; // 8: P, X, CC, M, PT, SN, TS
340 s->fec_arr_len = 1 + 2 * s->l; // row + column tmp + column out
342 if (h->flags & AVFMT_FLAG_BITEXACT) {
346 seed = av_get_random_seed();
347 s->rtp_col_sn = seed & 0x0fff;
348 s->rtp_row_sn = (seed >> 16) & 0x0fff;
351 s->fec_arr = av_malloc_array(s->fec_arr_len, sizeof (PrompegFec*));
355 for (i = 0; i < s->fec_arr_len; i++) {
356 s->fec_arr[i] = av_malloc(sizeof (PrompegFec));
357 if (!s->fec_arr[i]) {
360 s->fec_arr[i]->bitstring = av_malloc_array(s->bitstring_size, sizeof (uint8_t));
361 if (!s->fec_arr[i]->bitstring) {
362 av_freep(&s->fec_arr[i]);
366 s->fec_row = *s->fec_arr;
367 s->fec_col = s->fec_arr + 1;
368 s->fec_col_tmp = s->fec_arr + 1 + s->l;
370 s->rtp_buf = av_malloc_array(s->rtp_buf_size, sizeof (uint8_t));
374 memset(s->rtp_buf, 0, s->rtp_buf_size);
382 av_log(h, AV_LOG_ERROR, "Failed to allocate the FEC buffer\n");
383 return AVERROR(ENOMEM);
386 static int prompeg_write(URLContext *h, const uint8_t *buf, int size) {
387 PrompegContext *s = h->priv_data;
389 uint8_t *bitstring = NULL;
390 int col_idx, col_out_idx, row_idx;
391 int ret, written = 0;
393 if (s->init && ((ret = prompeg_init(h, buf, size)) < 0))
396 if ((ret = prompeg_create_bitstring(h, buf, size, &bitstring)) < 0)
399 col_idx = s->packet_idx % s->l;
400 row_idx = s->packet_idx / s->l % s->d;
402 // FEC' (row) send block-aligned, xor
404 if (!s->first || s->packet_idx > 0) {
405 if ((ret = prompeg_write_fec(h, s->fec_row, PROMPEG_FEC_ROW)) < 0)
409 memcpy(s->fec_row->bitstring, bitstring, s->bitstring_size);
410 s->fec_row->sn = AV_RB16(buf + 2);
411 s->fec_row->ts = AV_RB32(buf + 4);
413 xor_fast(s->fec_row->bitstring, bitstring, s->fec_row->bitstring,
420 // swap fec_col and fec_col_tmp
421 fec_tmp = s->fec_col[col_idx];
422 s->fec_col[col_idx] = s->fec_col_tmp[col_idx];
423 s->fec_col_tmp[col_idx] = fec_tmp;
425 memcpy(s->fec_col_tmp[col_idx]->bitstring, bitstring, s->bitstring_size);
426 s->fec_col_tmp[col_idx]->sn = AV_RB16(buf + 2);
427 s->fec_col_tmp[col_idx]->ts = AV_RB32(buf + 4);
429 xor_fast(s->fec_col_tmp[col_idx]->bitstring, bitstring,
430 s->fec_col_tmp[col_idx]->bitstring, s->bitstring_size);
433 // FEC (column) send block-aligned
434 if (!s->first && s->packet_idx % s->d == 0) {
435 col_out_idx = s->packet_idx / s->l;
436 if ((ret = prompeg_write_fec(h, s->fec_col[col_out_idx], PROMPEG_FEC_COL)) < 0)
441 if (++s->packet_idx >= s->packet_idx_max) {
454 static int prompeg_close(URLContext *h) {
455 PrompegContext *s = h->priv_data;
458 ffurl_closep(&s->fec_col_hd);
459 ffurl_closep(&s->fec_row_hd);
462 for (i = 0; i < s->fec_arr_len; i++) {
463 av_free(s->fec_arr[i]->bitstring);
464 av_freep(&s->fec_arr[i]);
466 av_freep(&s->fec_arr);
468 av_freep(&s->rtp_buf);
473 const URLProtocol ff_prompeg_protocol = {
475 .url_open = prompeg_open,
476 .url_write = prompeg_write,
477 .url_close = prompeg_close,
478 .priv_data_size = sizeof(PrompegContext),
479 .flags = URL_PROTOCOL_FLAG_NETWORK,
480 .priv_data_class = &prompeg_class,