src/lib/j2k_encoder_cpu_backend.cc

   1 /*
   2     Copyright (C) 2021 Carl Hetherington <cth@carlh.net>
   3
   4     This file is part of DCP-o-matic.
   5
   6     DCP-o-matic is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     DCP-o-matic 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 General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
  18
  19 */
  20
  21
  22 #include "config.h"
  23 #include "dcp_video.h"
  24 #include "dcpomatic_log.h"
  25 #include "j2k_encoder_cpu_backend.h"
  26 #include "player_video.h"
  27 #include "rng.h"
  28 #include <dcp/openjpeg_image.h>
  29 #include <dcp/j2k_transcode.h>
  30
  31 #include "i18n.h"
  32
  33
  34 using std::shared_ptr;
  35 using boost::optional;
  36 #if BOOST_VERSION >= 106100
  37 using namespace boost::placeholders;
  38 #endif
  39
  40
  41 optional<dcp::ArrayData>
  42 J2KEncoderCPUBackend::encode (DCPVideo video)
  43 {
  44         try {
  45                 auto const comment = Config::instance()->dcp_j2k_comment();
  46
  47                 /* This was empirically derived by a user: see #1902 */
  48                 int const minimum_size = 16384;
  49                 LOG_GENERAL ("Using minimum frame size %1", minimum_size);
  50
  51                 auto xyz = DCPVideo::convert_to_xyz (video.frame(), boost::bind(&Log::dcp_log, dcpomatic_log.get(), _1, _2));
  52                 int noise_amount = 2;
  53                 int pixel_skip = 16;
  54                 while (true) {
  55                         auto enc = dcp::compress_j2k (
  56                                 xyz,
  57                                 video.j2k_bandwidth(),
  58                                 video.frames_per_second(),
  59                                 video.frame()->eyes() == Eyes::LEFT || video.frame()->eyes() == Eyes::RIGHT,
  60                                 video.resolution() == Resolution::FOUR_K,
  61                                 comment.empty() ? "libdcp" : comment
  62                         );
  63
  64                         if (enc.size() >= minimum_size) {
  65                                 LOG_GENERAL (N_("Frame %1 encoded size was OK (%2)"), video.index(), enc.size());
  66                                 return enc;
  67                         }
  68
  69                         LOG_GENERAL (N_("Frame %1 encoded size was small (%2); adding noise at level %3 with pixel skip %4"), video.index(), enc.size(), noise_amount, pixel_skip);
  70
  71                         /* The JPEG2000 is too low-bitrate for some decoders <cough>DSS200</cough> so add some noise
  72                          * and try again.  This is slow but hopefully won't happen too often.  We have to do
  73                          * convert_to_xyz() again because compress_j2k() corrupts its xyz parameter.
  74                          */
  75
  76                         xyz = DCPVideo::convert_to_xyz (video.frame(), boost::bind(&Log::dcp_log, dcpomatic_log.get(), _1, _2));
  77                         auto const size = xyz->size ();
  78                         auto const pixels = size.width * size.height;
  79                         dcpomatic::RNG rng(42);
  80                         for (auto c = 0; c < 3; ++c) {
  81                                 auto p = xyz->data(c);
  82                                 auto e = xyz->data(c) + pixels;
  83                                 while (p < e) {
  84                                         *p = std::min(4095, std::max(0, *p + (rng.get() % noise_amount)));
  85                                         p += pixel_skip;
  86                                 }
  87                         }
  88
  89                         if (pixel_skip > 1) {
  90                                 --pixel_skip;
  91                         } else {
  92                                 ++noise_amount;
  93                         }
  94                         /* Something's gone badly wrong if this much noise doesn't help */
  95                         DCPOMATIC_ASSERT (noise_amount < 16);
  96                 }
  97
  98                 switch (video.frame()->eyes()) {
  99                 case Eyes::BOTH:
 100                         LOG_DEBUG_ENCODE (N_("Finished locally-encoded frame %1 for mono"), video.index());
 101                         break;
 102                 case Eyes::LEFT:
 103                         LOG_DEBUG_ENCODE (N_("Finished locally-encoded frame %1 for L"), video.index());
 104                         break;
 105                 case Eyes::RIGHT:
 106                         LOG_DEBUG_ENCODE (N_("Finished locally-encoded frame %1 for R"), video.index());
 107                         break;
 108                 default:
 109                         break;
 110                 }
 111         } catch (std::exception& e) {
 112                 LOG_ERROR (N_("Local encode failed (%1)"), e.what());
 113         }
 114
 115         return {};
 116 }
 117
 118