src/sound_asset_writer.cc

   1 /*
   2     Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
   3
   4     This file is part of libdcp.
   5
   6     libdcp 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     libdcp 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 libdcp.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "sound_asset_writer.h"
  21 #include "sound_asset.h"
  22 #include "exceptions.h"
  23 #include "dcp_assert.h"
  24 #include "compose.hpp"
  25 #include "AS_DCP.h"
  26
  27 using std::min;
  28 using std::max;
  29 using namespace dcp;
  30
  31 struct SoundAssetWriter::ASDCPState
  32 {
  33         ASDCP::PCM::MXFWriter mxf_writer;
  34         ASDCP::PCM::FrameBuffer frame_buffer;
  35         ASDCP::WriterInfo writer_info;
  36         ASDCP::PCM::AudioDescriptor audio_desc;
  37 };
  38
  39 SoundAssetWriter::SoundAssetWriter (SoundAsset* asset, boost::filesystem::path file, Standard standard)
  40         : AssetWriter (asset, file, standard)
  41         , _state (new SoundAssetWriter::ASDCPState)
  42         , _sound_asset (asset)
  43         , _frame_buffer_offset (0)
  44 {
  45         /* Derived from ASDCP::Wav::SimpleWaveHeader::FillADesc */
  46         _state->audio_desc.EditRate = ASDCP::Rational (_sound_asset->edit_rate().numerator, _sound_asset->edit_rate().denominator);
  47         _state->audio_desc.AudioSamplingRate = ASDCP::Rational (_sound_asset->sampling_rate(), 1);
  48         _state->audio_desc.Locked = 0;
  49         _state->audio_desc.ChannelCount = _sound_asset->channels ();
  50         _state->audio_desc.QuantizationBits = 24;
  51         _state->audio_desc.BlockAlign = 3 * _sound_asset->channels();
  52         _state->audio_desc.AvgBps = _sound_asset->sampling_rate() * _state->audio_desc.BlockAlign;
  53         _state->audio_desc.LinkedTrackID = 0;
  54         _state->audio_desc.ChannelFormat = ASDCP::PCM::CF_NONE;
  55
  56         _state->frame_buffer.Capacity (ASDCP::PCM::CalcFrameBufferSize (_state->audio_desc));
  57         _state->frame_buffer.Size (ASDCP::PCM::CalcFrameBufferSize (_state->audio_desc));
  58         memset (_state->frame_buffer.Data(), 0, _state->frame_buffer.Capacity());
  59
  60         _sound_asset->fill_writer_info (&_state->writer_info, _sound_asset->id(), standard);
  61 }
  62
  63 void
  64 SoundAssetWriter::write (float const * const * data, int frames)
  65 {
  66         DCP_ASSERT (!_finalized);
  67
  68         static float const clip = 1.0f - (1.0f / pow (2, 23));
  69
  70         if (!_started) {
  71                 Kumu::Result_t r = _state->mxf_writer.OpenWrite (_file.string().c_str(), _state->writer_info, _state->audio_desc);
  72                 if (ASDCP_FAILURE (r)) {
  73                         boost::throw_exception (FileError ("could not open audio MXF for writing", _file.string(), r));
  74                 }
  75
  76                 _sound_asset->set_file (_file);
  77                 _started = true;
  78         }
  79
  80         for (int i = 0; i < frames; ++i) {
  81
  82                 byte_t* out = _state->frame_buffer.Data() + _frame_buffer_offset;
  83
  84                 /* Write one sample per channel */
  85                 for (int j = 0; j < _sound_asset->channels(); ++j) {
  86                         /* Convert sample to 24-bit int, clipping if necessary. */
  87                         int32_t const s = min (clip, max (-clip, data[j][i])) * (1 << 23);
  88                         *out++ = (s & 0xff);
  89                         *out++ = (s & 0xff00) >> 8;
  90                         *out++ = (s & 0xff0000) >> 16;
  91                 }
  92                 _frame_buffer_offset += 3 * _sound_asset->channels();
  93
  94                 DCP_ASSERT (_frame_buffer_offset <= int (_state->frame_buffer.Capacity()));
  95
  96                 /* Finish the MXF frame if required */
  97                 if (_frame_buffer_offset == int (_state->frame_buffer.Capacity())) {
  98                         write_current_frame ();
  99                         _frame_buffer_offset = 0;
 100                         memset (_state->frame_buffer.Data(), 0, _state->frame_buffer.Capacity());
 101                 }
 102         }
 103 }
 104
 105 void
 106 SoundAssetWriter::write_current_frame ()
 107 {
 108         ASDCP::Result_t const r = _state->mxf_writer.WriteFrame (_state->frame_buffer, _encryption_context, _hmac_context);
 109         if (ASDCP_FAILURE (r)) {
 110                 boost::throw_exception (MiscError (String::compose ("could not write audio MXF frame (%1)", int (r))));
 111         }
 112
 113         ++_frames_written;
 114 }
 115
 116 bool
 117 SoundAssetWriter::finalize ()
 118 {
 119         if (_frame_buffer_offset > 0) {
 120                 write_current_frame ();
 121         }
 122
 123         if (_started && ASDCP_FAILURE (_state->mxf_writer.Finalize())) {
 124                 boost::throw_exception (MiscError ("could not finalise audio MXF"));
 125         }
 126
 127         _sound_asset->_intrinsic_duration = _frames_written;
 128         return AssetWriter::finalize ();
 129 }