libavformat/async.c

   1 /*
   2  * Input async protocol.
   3  * Copyright (c) 2015 Zhang Rui <bbcallen@gmail.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  * Based on libavformat/cache.c by Michael Niedermayer
  22  */
  23
  24  /**
  25  * @TODO
  26  *      support timeout
  27  *      support work with concatdec, hls
  28  */
  29
  30 #include "libavutil/avassert.h"
  31 #include "libavutil/avstring.h"
  32 #include "libavutil/error.h"
  33 #include "libavutil/fifo.h"
  34 #include "libavutil/log.h"
  35 #include "libavutil/opt.h"
  36 #include "libavutil/thread.h"
  37 #include "url.h"
  38 #include <stdint.h>
  39
  40 #if HAVE_UNISTD_H
  41 #include <unistd.h>
  42 #endif
  43
  44 #define BUFFER_CAPACITY         (4 * 1024 * 1024)
  45 #define READ_BACK_CAPACITY      (4 * 1024 * 1024)
  46 #define SHORT_SEEK_THRESHOLD    (256 * 1024)
  47
  48 typedef struct RingBuffer
  49 {
  50     AVFifoBuffer *fifo;
  51     int           read_back_capacity;
  52
  53     int           read_pos;
  54 } RingBuffer;
  55
  56 typedef struct Context {
  57     AVClass        *class;
  58     URLContext     *inner;
  59
  60     int             seek_request;
  61     int64_t         seek_pos;
  62     int             seek_whence;
  63     int             seek_completed;
  64     int64_t         seek_ret;
  65
  66     int             inner_io_error;
  67     int             io_error;
  68     int             io_eof_reached;
  69
  70     int64_t         logical_pos;
  71     int64_t         logical_size;
  72     RingBuffer      ring;
  73
  74     pthread_cond_t  cond_wakeup_main;
  75     pthread_cond_t  cond_wakeup_background;
  76     pthread_mutex_t mutex;
  77     pthread_t       async_buffer_thread;
  78
  79     int             abort_request;
  80     AVIOInterruptCB interrupt_callback;
  81 } Context;
  82
  83 static int ring_init(RingBuffer *ring, unsigned int capacity, int read_back_capacity)
  84 {
  85     memset(ring, 0, sizeof(RingBuffer));
  86     ring->fifo = av_fifo_alloc(capacity + read_back_capacity);
  87     if (!ring->fifo)
  88         return AVERROR(ENOMEM);
  89
  90     ring->read_back_capacity = read_back_capacity;
  91     return 0;
  92 }
  93
  94 static void ring_destroy(RingBuffer *ring)
  95 {
  96     av_fifo_freep(&ring->fifo);
  97 }
  98
  99 static void ring_reset(RingBuffer *ring)
 100 {
 101     av_fifo_reset(ring->fifo);
 102     ring->read_pos = 0;
 103 }
 104
 105 static int ring_size(RingBuffer *ring)
 106 {
 107     return av_fifo_size(ring->fifo) - ring->read_pos;
 108 }
 109
 110 static int ring_space(RingBuffer *ring)
 111 {
 112     return av_fifo_space(ring->fifo);
 113 }
 114
 115 static int ring_generic_read(RingBuffer *ring, void *dest, int buf_size, void (*func)(void*, void*, int))
 116 {
 117     int ret;
 118
 119     av_assert2(buf_size <= ring_size(ring));
 120     ret = av_fifo_generic_peek_at(ring->fifo, dest, ring->read_pos, buf_size, func);
 121     ring->read_pos += buf_size;
 122
 123     if (ring->read_pos > ring->read_back_capacity) {
 124         av_fifo_drain(ring->fifo, ring->read_pos - ring->read_back_capacity);
 125         ring->read_pos = ring->read_back_capacity;
 126     }
 127
 128     return ret;
 129 }
 130
 131 static int ring_generic_write(RingBuffer *ring, void *src, int size, int (*func)(void*, void*, int))
 132 {
 133     av_assert2(size <= ring_space(ring));
 134     return av_fifo_generic_write(ring->fifo, src, size, func);
 135 }
 136
 137 static int ring_size_of_read_back(RingBuffer *ring)
 138 {
 139     return ring->read_pos;
 140 }
 141
 142 static int ring_drain(RingBuffer *ring, int offset)
 143 {
 144     av_assert2(offset >= -ring_size_of_read_back(ring));
 145     av_assert2(offset <= ring_size(ring));
 146     ring->read_pos += offset;
 147     return 0;
 148 }
 149
 150 static int async_check_interrupt(void *arg)
 151 {
 152     URLContext *h   = arg;
 153     Context    *c   = h->priv_data;
 154
 155     if (c->abort_request)
 156         return 1;
 157
 158     if (ff_check_interrupt(&c->interrupt_callback))
 159         c->abort_request = 1;
 160
 161     return c->abort_request;
 162 }
 163
 164 static int wrapped_url_read(void *src, void *dst, int size)
 165 {
 166     URLContext *h   = src;
 167     Context    *c   = h->priv_data;
 168     int         ret;
 169
 170     ret = ffurl_read(c->inner, dst, size);
 171     c->inner_io_error = ret < 0 ? ret : 0;
 172
 173     return ret;
 174 }
 175
 176 static void *async_buffer_task(void *arg)
 177 {
 178     URLContext   *h    = arg;
 179     Context      *c    = h->priv_data;
 180     RingBuffer   *ring = &c->ring;
 181     int           ret  = 0;
 182     int64_t       seek_ret;
 183
 184     while (1) {
 185         int fifo_space, to_copy;
 186
 187         pthread_mutex_lock(&c->mutex);
 188         if (async_check_interrupt(h)) {
 189             c->io_eof_reached = 1;
 190             c->io_error       = AVERROR_EXIT;
 191             pthread_cond_signal(&c->cond_wakeup_main);
 192             pthread_mutex_unlock(&c->mutex);
 193             break;
 194         }
 195
 196         if (c->seek_request) {
 197             seek_ret = ffurl_seek(c->inner, c->seek_pos, c->seek_whence);
 198             if (seek_ret >= 0) {
 199                 c->io_eof_reached = 0;
 200                 c->io_error       = 0;
 201                 ring_reset(ring);
 202             }
 203
 204             c->seek_completed = 1;
 205             c->seek_ret       = seek_ret;
 206             c->seek_request   = 0;
 207
 208
 209             pthread_cond_signal(&c->cond_wakeup_main);
 210             pthread_mutex_unlock(&c->mutex);
 211             continue;
 212         }
 213
 214         fifo_space = ring_space(ring);
 215         if (c->io_eof_reached || fifo_space <= 0) {
 216             pthread_cond_signal(&c->cond_wakeup_main);
 217             pthread_cond_wait(&c->cond_wakeup_background, &c->mutex);
 218             pthread_mutex_unlock(&c->mutex);
 219             continue;
 220         }
 221         pthread_mutex_unlock(&c->mutex);
 222
 223         to_copy = FFMIN(4096, fifo_space);
 224         ret = ring_generic_write(ring, (void *)h, to_copy, wrapped_url_read);
 225
 226         pthread_mutex_lock(&c->mutex);
 227         if (ret <= 0) {
 228             c->io_eof_reached = 1;
 229             if (c->inner_io_error < 0)
 230                 c->io_error = c->inner_io_error;
 231         }
 232
 233         pthread_cond_signal(&c->cond_wakeup_main);
 234         pthread_mutex_unlock(&c->mutex);
 235     }
 236
 237     return NULL;
 238 }
 239
 240 static int async_open(URLContext *h, const char *arg, int flags, AVDictionary **options)
 241 {
 242     Context         *c = h->priv_data;
 243     int              ret;
 244     AVIOInterruptCB  interrupt_callback = {.callback = async_check_interrupt, .opaque = h};
 245
 246     av_strstart(arg, "async:", &arg);
 247
 248     ret = ring_init(&c->ring, BUFFER_CAPACITY, READ_BACK_CAPACITY);
 249     if (ret < 0)
 250         goto fifo_fail;
 251
 252     /* wrap interrupt callback */
 253     c->interrupt_callback = h->interrupt_callback;
 254     ret = ffurl_open_whitelist(&c->inner, arg, flags, &interrupt_callback, options, h->protocol_whitelist, h->protocol_blacklist, h);
 255     if (ret != 0) {
 256         av_log(h, AV_LOG_ERROR, "ffurl_open failed : %s, %s\n", av_err2str(ret), arg);
 257         goto url_fail;
 258     }
 259
 260     c->logical_size = ffurl_size(c->inner);
 261     h->is_streamed  = c->inner->is_streamed;
 262
 263     ret = pthread_mutex_init(&c->mutex, NULL);
 264     if (ret != 0) {
 265         ret = AVERROR(ret);
 266         av_log(h, AV_LOG_ERROR, "pthread_mutex_init failed : %s\n", av_err2str(ret));
 267         goto mutex_fail;
 268     }
 269
 270     ret = pthread_cond_init(&c->cond_wakeup_main, NULL);
 271     if (ret != 0) {
 272         ret = AVERROR(ret);
 273         av_log(h, AV_LOG_ERROR, "pthread_cond_init failed : %s\n", av_err2str(ret));
 274         goto cond_wakeup_main_fail;
 275     }
 276
 277     ret = pthread_cond_init(&c->cond_wakeup_background, NULL);
 278     if (ret != 0) {
 279         ret = AVERROR(ret);
 280         av_log(h, AV_LOG_ERROR, "pthread_cond_init failed : %s\n", av_err2str(ret));
 281         goto cond_wakeup_background_fail;
 282     }
 283
 284     ret = pthread_create(&c->async_buffer_thread, NULL, async_buffer_task, h);
 285     if (ret) {
 286         ret = AVERROR(ret);
 287         av_log(h, AV_LOG_ERROR, "pthread_create failed : %s\n", av_err2str(ret));
 288         goto thread_fail;
 289     }
 290
 291     return 0;
 292
 293 thread_fail:
 294     pthread_cond_destroy(&c->cond_wakeup_background);
 295 cond_wakeup_background_fail:
 296     pthread_cond_destroy(&c->cond_wakeup_main);
 297 cond_wakeup_main_fail:
 298     pthread_mutex_destroy(&c->mutex);
 299 mutex_fail:
 300     ffurl_closep(&c->inner);
 301 url_fail:
 302     ring_destroy(&c->ring);
 303 fifo_fail:
 304     return ret;
 305 }
 306
 307 static int async_close(URLContext *h)
 308 {
 309     Context *c = h->priv_data;
 310     int      ret;
 311
 312     pthread_mutex_lock(&c->mutex);
 313     c->abort_request = 1;
 314     pthread_cond_signal(&c->cond_wakeup_background);
 315     pthread_mutex_unlock(&c->mutex);
 316
 317     ret = pthread_join(c->async_buffer_thread, NULL);
 318     if (ret != 0)
 319         av_log(h, AV_LOG_ERROR, "pthread_join(): %s\n", av_err2str(ret));
 320
 321     pthread_cond_destroy(&c->cond_wakeup_background);
 322     pthread_cond_destroy(&c->cond_wakeup_main);
 323     pthread_mutex_destroy(&c->mutex);
 324     ffurl_closep(&c->inner);
 325     ring_destroy(&c->ring);
 326
 327     return 0;
 328 }
 329
 330 static int async_read_internal(URLContext *h, void *dest, int size, int read_complete,
 331                                void (*func)(void*, void*, int))
 332 {
 333     Context      *c       = h->priv_data;
 334     RingBuffer   *ring    = &c->ring;
 335     int           to_read = size;
 336     int           ret     = 0;
 337
 338     pthread_mutex_lock(&c->mutex);
 339
 340     while (to_read > 0) {
 341         int fifo_size, to_copy;
 342         if (async_check_interrupt(h)) {
 343             ret = AVERROR_EXIT;
 344             break;
 345         }
 346         fifo_size = ring_size(ring);
 347         to_copy   = FFMIN(to_read, fifo_size);
 348         if (to_copy > 0) {
 349             ring_generic_read(ring, dest, to_copy, func);
 350             if (!func)
 351                 dest = (uint8_t *)dest + to_copy;
 352             c->logical_pos += to_copy;
 353             to_read        -= to_copy;
 354             ret             = size - to_read;
 355
 356             if (to_read <= 0 || !read_complete)
 357                 break;
 358         } else if (c->io_eof_reached) {
 359             if (ret <= 0) {
 360                 if (c->io_error)
 361                     ret = c->io_error;
 362                 else
 363                     ret = AVERROR_EOF;
 364             }
 365             break;
 366         }
 367         pthread_cond_signal(&c->cond_wakeup_background);
 368         pthread_cond_wait(&c->cond_wakeup_main, &c->mutex);
 369     }
 370
 371     pthread_cond_signal(&c->cond_wakeup_background);
 372     pthread_mutex_unlock(&c->mutex);
 373
 374     return ret;
 375 }
 376
 377 static int async_read(URLContext *h, unsigned char *buf, int size)
 378 {
 379     return async_read_internal(h, buf, size, 0, NULL);
 380 }
 381
 382 static void fifo_do_not_copy_func(void* dest, void* src, int size) {
 383     // do not copy
 384 }
 385
 386 static int64_t async_seek(URLContext *h, int64_t pos, int whence)
 387 {
 388     Context      *c    = h->priv_data;
 389     RingBuffer   *ring = &c->ring;
 390     int64_t       ret;
 391     int64_t       new_logical_pos;
 392     int fifo_size;
 393     int fifo_size_of_read_back;
 394
 395     if (whence == AVSEEK_SIZE) {
 396         av_log(h, AV_LOG_TRACE, "async_seek: AVSEEK_SIZE: %"PRId64"\n", (int64_t)c->logical_size);
 397         return c->logical_size;
 398     } else if (whence == SEEK_CUR) {
 399         av_log(h, AV_LOG_TRACE, "async_seek: %"PRId64"\n", pos);
 400         new_logical_pos = pos + c->logical_pos;
 401     } else if (whence == SEEK_SET){
 402         av_log(h, AV_LOG_TRACE, "async_seek: %"PRId64"\n", pos);
 403         new_logical_pos = pos;
 404     } else {
 405         return AVERROR(EINVAL);
 406     }
 407     if (new_logical_pos < 0)
 408         return AVERROR(EINVAL);
 409
 410     fifo_size = ring_size(ring);
 411     fifo_size_of_read_back = ring_size_of_read_back(ring);
 412     if (new_logical_pos == c->logical_pos) {
 413         /* current position */
 414         return c->logical_pos;
 415     } else if ((new_logical_pos >= (c->logical_pos - fifo_size_of_read_back)) &&
 416                (new_logical_pos < (c->logical_pos + fifo_size + SHORT_SEEK_THRESHOLD))) {
 417         int pos_delta = (int)(new_logical_pos - c->logical_pos);
 418         /* fast seek */
 419         av_log(h, AV_LOG_TRACE, "async_seek: fask_seek %"PRId64" from %d dist:%d/%d\n",
 420                 new_logical_pos, (int)c->logical_pos,
 421                 (int)(new_logical_pos - c->logical_pos), fifo_size);
 422
 423         if (pos_delta > 0) {
 424             // fast seek forwards
 425             async_read_internal(h, NULL, pos_delta, 1, fifo_do_not_copy_func);
 426         } else {
 427             // fast seek backwards
 428             ring_drain(ring, pos_delta);
 429             c->logical_pos = new_logical_pos;
 430         }
 431
 432         return c->logical_pos;
 433     } else if (c->logical_size <= 0) {
 434         /* can not seek */
 435         return AVERROR(EINVAL);
 436     } else if (new_logical_pos > c->logical_size) {
 437         /* beyond end */
 438         return AVERROR(EINVAL);
 439     }
 440
 441     pthread_mutex_lock(&c->mutex);
 442
 443     c->seek_request   = 1;
 444     c->seek_pos       = new_logical_pos;
 445     c->seek_whence    = SEEK_SET;
 446     c->seek_completed = 0;
 447     c->seek_ret       = 0;
 448
 449     while (1) {
 450         if (async_check_interrupt(h)) {
 451             ret = AVERROR_EXIT;
 452             break;
 453         }
 454         if (c->seek_completed) {
 455             if (c->seek_ret >= 0)
 456                 c->logical_pos  = c->seek_ret;
 457             ret = c->seek_ret;
 458             break;
 459         }
 460         pthread_cond_signal(&c->cond_wakeup_background);
 461         pthread_cond_wait(&c->cond_wakeup_main, &c->mutex);
 462     }
 463
 464     pthread_mutex_unlock(&c->mutex);
 465
 466     return ret;
 467 }
 468
 469 #define OFFSET(x) offsetof(Context, x)
 470 #define D AV_OPT_FLAG_DECODING_PARAM
 471
 472 static const AVOption options[] = {
 473     {NULL},
 474 };
 475
 476 #undef D
 477 #undef OFFSET
 478
 479 static const AVClass async_context_class = {
 480     .class_name = "Async",
 481     .item_name  = av_default_item_name,
 482     .option     = options,
 483     .version    = LIBAVUTIL_VERSION_INT,
 484 };
 485
 486 const URLProtocol ff_async_protocol = {
 487     .name                = "async",
 488     .url_open2           = async_open,
 489     .url_read            = async_read,
 490     .url_seek            = async_seek,
 491     .url_close           = async_close,
 492     .priv_data_size      = sizeof(Context),
 493     .priv_data_class     = &async_context_class,
 494 };
 495
 496 #if 0
 497
 498 #define TEST_SEEK_POS    (1536)
 499 #define TEST_STREAM_SIZE (2048)
 500
 501 typedef struct TestContext {
 502     AVClass        *class;
 503     int64_t         logical_pos;
 504     int64_t         logical_size;
 505
 506     /* options */
 507     int             opt_read_error;
 508 } TestContext;
 509
 510 static int async_test_open(URLContext *h, const char *arg, int flags, AVDictionary **options)
 511 {
 512     TestContext *c = h->priv_data;
 513     c->logical_pos  = 0;
 514     c->logical_size = TEST_STREAM_SIZE;
 515     return 0;
 516 }
 517
 518 static int async_test_close(URLContext *h)
 519 {
 520     return 0;
 521 }
 522
 523 static int async_test_read(URLContext *h, unsigned char *buf, int size)
 524 {
 525     TestContext *c = h->priv_data;
 526     int          i;
 527     int          read_len = 0;
 528
 529     if (c->opt_read_error)
 530         return c->opt_read_error;
 531
 532     if (c->logical_pos >= c->logical_size)
 533         return AVERROR_EOF;
 534
 535     for (i = 0; i < size; ++i) {
 536         buf[i] = c->logical_pos & 0xFF;
 537
 538         c->logical_pos++;
 539         read_len++;
 540
 541         if (c->logical_pos >= c->logical_size)
 542             break;
 543     }
 544
 545     return read_len;
 546 }
 547
 548 static int64_t async_test_seek(URLContext *h, int64_t pos, int whence)
 549 {
 550     TestContext *c = h->priv_data;
 551     int64_t      new_logical_pos;
 552
 553     if (whence == AVSEEK_SIZE) {
 554         return c->logical_size;
 555     } else if (whence == SEEK_CUR) {
 556         new_logical_pos = pos + c->logical_pos;
 557     } else if (whence == SEEK_SET){
 558         new_logical_pos = pos;
 559     } else {
 560         return AVERROR(EINVAL);
 561     }
 562     if (new_logical_pos < 0)
 563         return AVERROR(EINVAL);
 564
 565     c->logical_pos = new_logical_pos;
 566     return new_logical_pos;
 567 }
 568
 569 #define OFFSET(x) offsetof(TestContext, x)
 570 #define D AV_OPT_FLAG_DECODING_PARAM
 571
 572 static const AVOption async_test_options[] = {
 573     { "async-test-read-error",      "cause read fail",
 574         OFFSET(opt_read_error),     AV_OPT_TYPE_INT, { .i64 = 0 }, INT_MIN, INT_MAX, .flags = D },
 575     {NULL},
 576 };
 577
 578 #undef D
 579 #undef OFFSET
 580
 581 static const AVClass async_test_context_class = {
 582     .class_name = "Async-Test",
 583     .item_name  = av_default_item_name,
 584     .option     = async_test_options,
 585     .version    = LIBAVUTIL_VERSION_INT,
 586 };
 587
 588 const URLProtocol ff_async_test_protocol = {
 589     .name                = "async-test",
 590     .url_open2           = async_test_open,
 591     .url_read            = async_test_read,
 592     .url_seek            = async_test_seek,
 593     .url_close           = async_test_close,
 594     .priv_data_size      = sizeof(TestContext),
 595     .priv_data_class     = &async_test_context_class,
 596 };
 597
 598 int main(void)
 599 {
 600     URLContext   *h = NULL;
 601     int           i;
 602     int           ret;
 603     int64_t       size;
 604     int64_t       pos;
 605     int64_t       read_len;
 606     unsigned char buf[4096];
 607     AVDictionary *opts = NULL;
 608
 609     ffurl_register_protocol(&ff_async_protocol);
 610     ffurl_register_protocol(&ff_async_test_protocol);
 611
 612     /*
 613      * test normal read
 614      */
 615     ret = ffurl_open_whitelist(&h, "async:async-test:", AVIO_FLAG_READ,
 616                                NULL, NULL, NULL, NULL, NULL);
 617     printf("open: %d\n", ret);
 618
 619     size = ffurl_size(h);
 620     printf("size: %"PRId64"\n", size);
 621
 622     pos = ffurl_seek(h, 0, SEEK_CUR);
 623     read_len = 0;
 624     while (1) {
 625         ret = ffurl_read(h, buf, sizeof(buf));
 626         if (ret == AVERROR_EOF) {
 627             printf("read-error: AVERROR_EOF at %"PRId64"\n", ffurl_seek(h, 0, SEEK_CUR));
 628             break;
 629         }
 630         else if (ret == 0)
 631             break;
 632         else if (ret < 0) {
 633             printf("read-error: %d at %"PRId64"\n", ret, ffurl_seek(h, 0, SEEK_CUR));
 634             goto fail;
 635         } else {
 636             for (i = 0; i < ret; ++i) {
 637                 if (buf[i] != (pos & 0xFF)) {
 638                     printf("read-mismatch: actual %d, expecting %d, at %"PRId64"\n",
 639                            (int)buf[i], (int)(pos & 0xFF), pos);
 640                     break;
 641                 }
 642                 pos++;
 643             }
 644         }
 645
 646         read_len += ret;
 647     }
 648     printf("read: %"PRId64"\n", read_len);
 649
 650     /*
 651      * test normal seek
 652      */
 653     ret = ffurl_read(h, buf, 1);
 654     printf("read: %d\n", ret);
 655
 656     pos = ffurl_seek(h, TEST_SEEK_POS, SEEK_SET);
 657     printf("seek: %"PRId64"\n", pos);
 658
 659     read_len = 0;
 660     while (1) {
 661         ret = ffurl_read(h, buf, sizeof(buf));
 662         if (ret == AVERROR_EOF)
 663             break;
 664         else if (ret == 0)
 665             break;
 666         else if (ret < 0) {
 667             printf("read-error: %d at %"PRId64"\n", ret, ffurl_seek(h, 0, SEEK_CUR));
 668             goto fail;
 669         } else {
 670             for (i = 0; i < ret; ++i) {
 671                 if (buf[i] != (pos & 0xFF)) {
 672                     printf("read-mismatch: actual %d, expecting %d, at %"PRId64"\n",
 673                            (int)buf[i], (int)(pos & 0xFF), pos);
 674                     break;
 675                 }
 676                 pos++;
 677             }
 678         }
 679
 680         read_len += ret;
 681     }
 682     printf("read: %"PRId64"\n", read_len);
 683
 684     ret = ffurl_read(h, buf, 1);
 685     printf("read: %d\n", ret);
 686
 687     /*
 688      * test read error
 689      */
 690     ffurl_close(h);
 691     av_dict_set_int(&opts, "async-test-read-error", -10000, 0);
 692     ret = ffurl_open_whitelist(&h, "async:async-test:", AVIO_FLAG_READ,
 693                                NULL, &opts, NULL, NULL, NULL);
 694     printf("open: %d\n", ret);
 695
 696     ret = ffurl_read(h, buf, 1);
 697     printf("read: %d\n", ret);
 698
 699 fail:
 700     av_dict_free(&opts);
 701     ffurl_close(h);
 702     return 0;
 703 }
 704
 705 #endif