Subversion Repositories Kolibri OS

Rev

Blame | Last modification | View Log | RSS feed

  1. /*
  2.  * Copyright (c) 2014 Nicolas George
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public License
  8.  * as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  11.  * FFmpeg is distributed in the hope that it will be useful,
  12.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14.  * GNU Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public License
  17.  * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
  18.  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. #include "libavutil/avassert.h"
  22. #include "libavutil/avstring.h"
  23. #include "libavutil/opt.h"
  24. #include "avformat.h"
  25. #include "url.h"
  26.  
  27. typedef struct SubfileContext {
  28.     const AVClass *class;
  29.     URLContext *h;
  30.     int64_t start;
  31.     int64_t end;
  32.     int64_t pos;
  33. } SubfileContext;
  34.  
  35. #define OFFSET(field) offsetof(SubfileContext, field)
  36. #define D AV_OPT_FLAG_DECODING_PARAM
  37.  
  38. static const AVOption subfile_options[] = {
  39.     { "start", "start offset", OFFSET(start), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D },
  40.     { "end",   "end offset",   OFFSET(end),   AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D },
  41.     { NULL }
  42. };
  43.  
  44. #undef OFFSET
  45. #undef D
  46.  
  47. static const AVClass subfile_class = {
  48.     .class_name = "subfile",
  49.     .item_name  = av_default_item_name,
  50.     .option     = subfile_options,
  51.     .version    = LIBAVUTIL_VERSION_INT,
  52. };
  53.  
  54. static int slave_seek(URLContext *h)
  55. {
  56.     SubfileContext *c = h->priv_data;
  57.     int64_t ret;
  58.  
  59.     if ((ret = ffurl_seek(c->h, c->pos, SEEK_SET)) != c->pos) {
  60.         if (ret >= 0)
  61.             ret = AVERROR_BUG;
  62.         av_log(h, AV_LOG_ERROR, "Impossible to seek in file: %s\n",
  63.                av_err2str(ret));
  64.         return ret;
  65.     }
  66.     return 0;
  67. }
  68.  
  69. static int subfile_open(URLContext *h, const char *filename, int flags,
  70.                         AVDictionary **options)
  71. {
  72.     SubfileContext *c = h->priv_data;
  73.     int ret;
  74.  
  75.     if (c->end <= c->start) {
  76.         av_log(h, AV_LOG_ERROR, "end before start\n");
  77.         return AVERROR(EINVAL);
  78.     }
  79.     av_strstart(filename, "subfile:", &filename);
  80.     ret = ffurl_open(&c->h, filename, flags, &h->interrupt_callback, options);
  81.     if (ret < 0)
  82.         return ret;
  83.     c->pos = c->start;
  84.     if ((ret = slave_seek(h)) < 0) {
  85.         ffurl_close(c->h);
  86.         return ret;
  87.     }
  88.     return 0;
  89. }
  90.  
  91. static int subfile_close(URLContext *h)
  92. {
  93.     SubfileContext *c = h->priv_data;
  94.     return ffurl_close(c->h);
  95. }
  96.  
  97. static int subfile_read(URLContext *h, unsigned char *buf, int size)
  98. {
  99.     SubfileContext *c = h->priv_data;
  100.     int64_t rest = c->end - c->pos;
  101.     int ret;
  102.  
  103.     if (rest <= 0)
  104.         return 0;
  105.     size = FFMIN(size, rest);
  106.     ret = ffurl_read(c->h, buf, size);
  107.     if (ret >= 0)
  108.         c->pos += ret;
  109.     return ret;
  110. }
  111.  
  112. static int64_t subfile_seek(URLContext *h, int64_t pos, int whence)
  113. {
  114.     SubfileContext *c = h->priv_data;
  115.     int64_t new_pos = -1;
  116.     int ret;
  117.  
  118.     if (whence == AVSEEK_SIZE)
  119.         return c->end - c->start;
  120.     switch (whence) {
  121.     case SEEK_SET:
  122.         new_pos = c->start + pos;
  123.         break;
  124.     case SEEK_CUR:
  125.         new_pos += pos;
  126.         break;
  127.     case SEEK_END:
  128.         new_pos = c->end + c->pos;
  129.         break;
  130.     }
  131.     if (new_pos < c->start)
  132.         return AVERROR(EINVAL);
  133.     c->pos = new_pos;
  134.     if ((ret = slave_seek(h)) < 0)
  135.         return ret;
  136.     return c->pos - c->start;
  137. }
  138.  
  139. URLProtocol ff_subfile_protocol = {
  140.     .name                = "subfile",
  141.     .url_open2           = subfile_open,
  142.     .url_read            = subfile_read,
  143.     .url_seek            = subfile_seek,
  144.     .url_close           = subfile_close,
  145.     .priv_data_size      = sizeof(SubfileContext),
  146.     .priv_data_class     = &subfile_class,
  147. };
  148.