src/soundloader_opus.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file sound_opus.cpp Loading of opus sounds. */
   9
  10 #include "stdafx.h"
  11 #include "random_access_file_type.h"
  12 #include "sound_type.h"
  13 #include "soundloader_type.h"
  14
  15 #include <opusfile.h>
  16
  17 #include "safeguards.h"
  18
  19 /** Opus sound loader. */
  20 class SoundLoader_Opus : public SoundLoader {
  21 public:
  22         SoundLoader_Opus() : SoundLoader("opus", "Opus sound loader", 10) {}
  23
  24         static constexpr uint16_t OPUS_SAMPLE_RATE = 48000; ///< OpusFile always decodes at 48kHz.
  25         static constexpr uint8_t OPUS_SAMPLE_BITS = 16; ///< OpusFile op_read() uses 16 bits per sample.
  26
  27         /* For good results, you will need at least 57 bytes (for a pure Opus-only stream). */
  28         static constexpr size_t MIN_OPUS_FILE_SIZE = 57U;
  29
  30         /* It is recommended that this be large enough for at least 120 ms of data at 48 kHz per channel (5760 values per channel).
  31          * Smaller buffers will simply return less data, possibly consuming more memory to buffer the data internally. */
  32         static constexpr size_t DECODE_BUFFER_SAMPLES = 5760 * 2;
  33         static constexpr size_t DECODE_BUFFER_BYTES = DECODE_BUFFER_SAMPLES * sizeof(opus_int16);
  34
  35         bool Load(SoundEntry &sound, bool new_format, std::vector<uint8_t> &data) override
  36         {
  37                 if (!new_format) return false;
  38
  39                 /* At least 57 bytes are needed for an Opus-only file. */
  40                 if (sound.file_size < MIN_OPUS_FILE_SIZE) return false;
  41
  42                 /* Test if data is an Ogg Opus stream, as identified by the initial file header. */
  43                 auto filepos = sound.file->GetPos();
  44                 std::vector<uint8_t> tmp(MIN_OPUS_FILE_SIZE);
  45                 sound.file->ReadBlock(tmp.data(), tmp.size());
  46                 if (op_test(nullptr, tmp.data(), tmp.size()) != 0) return false;
  47
  48                 /* Read the whole file into memory. */
  49                 tmp.resize(sound.file_size);
  50                 sound.file->SeekTo(filepos, SEEK_SET);
  51                 sound.file->ReadBlock(tmp.data(), tmp.size());
  52
  53                 int error = 0;
  54                 auto of = std::unique_ptr<OggOpusFile, OggOpusFileDeleter>(op_open_memory(tmp.data(), tmp.size(), &error));
  55                 if (error != 0) return false;
  56
  57                 size_t datapos = 0;
  58                 for (;;) {
  59                         data.resize(datapos + DECODE_BUFFER_BYTES);
  60
  61                         int link_index;
  62                         int read = op_read(of.get(), reinterpret_cast<opus_int16 *>(&data[datapos]), DECODE_BUFFER_BYTES, &link_index);
  63                         if (read == 0) break;
  64
  65                         if (read < 0 || op_channel_count(of.get(), link_index) != 1) {
  66                                 /* Error reading, or incorrect channel count. */
  67                                 data.clear();
  68                                 return false;
  69                         }
  70
  71                         datapos += read * sizeof(opus_int16);
  72                 }
  73
  74                 /* OpusFile always decodes at 48kHz. */
  75                 sound.channels = 1;
  76                 sound.bits_per_sample = OPUS_SAMPLE_BITS;
  77                 sound.rate = OPUS_SAMPLE_RATE;
  78
  79                 /* We resized by DECODE_BUFFER_BYTES just before finally reading zero bytes, undo this. */
  80                 data.resize(data.size() - DECODE_BUFFER_BYTES);
  81
  82                 return true;
  83         }
  84
  85 private:
  86         /** Helper class to RAII release an OggOpusFile. */
  87         struct OggOpusFileDeleter {
  88                 void operator()(OggOpusFile *of)
  89                 {
  90                         if (of != nullptr) op_free(of);
  91                 }
  92         };
  93 };
  94
  95 static SoundLoader_Opus s_sound_loader_opus;