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
  21 #include "sound_asset_writer.h"
  22 #include "sound_asset.h"
  23 #include "exceptions.h"
  24 #include "dcp_assert.h"
  25 #include "compose.hpp"
  26 #include "AS_DCP.h"
  27
  28 using std::min;
  29 using std::max;
  30 using namespace dcp;
  31
  32 struct SoundAssetWriter::ASDCPState
  33 {
  34         ASDCP::PCM::MXFWriter mxf_writer;
  35         ASDCP::PCM::FrameBuffer frame_buffer;
  36         ASDCP::WriterInfo writer_info;
  37         ASDCP::PCM::AudioDescriptor audio_desc;
  38 };
  39
  40 SoundAssetWriter::SoundAssetWriter (SoundAsset* asset, boost::filesystem::path file, Standard standard)
  41         : AssetWriter (asset, file, standard)
  42         , _state (new SoundAssetWriter::ASDCPState)
  43         , _sound_asset (asset)
  44         , _frame_buffer_offset (0)
  45 {
  46         /* Derived from ASDCP::Wav::SimpleWaveHeader::FillADesc */
  47         _state->audio_desc.EditRate = ASDCP::Rational (_sound_asset->edit_rate().numerator, _sound_asset->edit_rate().denominator);
  48         _state->audio_desc.AudioSamplingRate = ASDCP::Rational (_sound_asset->sampling_rate(), 1);
  49         _state->audio_desc.Locked = 0;
  50         _state->audio_desc.ChannelCount = _sound_asset->channels ();
  51         _state->audio_desc.QuantizationBits = 24;
  52         _state->audio_desc.BlockAlign = 3 * _sound_asset->channels();
  53         _state->audio_desc.AvgBps = _sound_asset->sampling_rate() * _state->audio_desc.BlockAlign;
  54         _state->audio_desc.LinkedTrackID = 0;
  55         _state->audio_desc.ChannelFormat = ASDCP::PCM::CF_NONE;
  56
  57         _state->frame_buffer.Capacity (ASDCP::PCM::CalcFrameBufferSize (_state->audio_desc));
  58         _state->frame_buffer.Size (ASDCP::PCM::CalcFrameBufferSize (_state->audio_desc));
  59         memset (_state->frame_buffer.Data(), 0, _state->frame_buffer.Capacity());
  60
  61         _sound_asset->fill_writer_info (&_state->writer_info, _sound_asset->id(), standard);
  62 }
  63
  64 void
  65 SoundAssetWriter::write (float const * const * data, int frames)
  66 {
  67         DCP_ASSERT (!_finalized);
  68
  69         static float const clip = 1.0f - (1.0f / pow (2, 23));
  70
  71         if (!_started) {
  72                 Kumu::Result_t r = _state->mxf_writer.OpenWrite (_file.string().c_str(), _state->writer_info, _state->audio_desc);
  73                 if (ASDCP_FAILURE (r)) {
  74                         boost::throw_exception (FileError ("could not open audio MXF for writing", _file.string(), r));
  75                 }
  76
  77                 _sound_asset->set_file (_file);
  78                 _started = true;
  79         }
  80
  81         for (int i = 0; i < frames; ++i) {
  82
  83                 byte_t* out = _state->frame_buffer.Data() + _frame_buffer_offset;
  84
  85                 /* Write one sample per channel */
  86                 for (int j = 0; j < _sound_asset->channels(); ++j) {
  87                         /* Convert sample to 24-bit int, clipping if necessary. */
  88                         int32_t const s = min (clip, max (-clip, data[j][i])) * (1 << 23);
  89                         *out++ = (s & 0xff);
  90                         *out++ = (s & 0xff00) >> 8;
  91                         *out++ = (s & 0xff0000) >> 16;
  92                 }
  93                 _frame_buffer_offset += 3 * _sound_asset->channels();
  94
  95                 DCP_ASSERT (_frame_buffer_offset <= int (_state->frame_buffer.Capacity()));
  96
  97                 /* Finish the MXF frame if required */
  98                 if (_frame_buffer_offset == int (_state->frame_buffer.Capacity())) {
  99                         write_current_frame ();
 100                         _frame_buffer_offset = 0;
 101                         memset (_state->frame_buffer.Data(), 0, _state->frame_buffer.Capacity());
 102                 }
 103         }
 104 }
 105
 106 void
 107 SoundAssetWriter::write_current_frame ()
 108 {
 109         ASDCP::Result_t const r = _state->mxf_writer.WriteFrame (_state->frame_buffer, _encryption_context, _hmac_context);
 110         if (ASDCP_FAILURE (r)) {
 111                 boost::throw_exception (MiscError (String::compose ("could not write audio MXF frame (%1)", int (r))));
 112         }
 113
 114         ++_frames_written;
 115 }
 116
 117 bool
 118 SoundAssetWriter::finalize ()
 119 {
 120         if (_frame_buffer_offset > 0) {
 121                 write_current_frame ();
 122         }
 123
 124         if (_started && ASDCP_FAILURE (_state->mxf_writer.Finalize())) {
 125                 boost::throw_exception (MiscError ("could not finalise audio MXF"));
 126         }
 127
 128         _sound_asset->_intrinsic_duration = _frames_written;
 129         return AssetWriter::finalize ();
 130 }