2 Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 #include "audio_decoder.h"
21 #include "audio_buffers.h"
22 #include "exceptions.h"
24 #include "resampler.h"
27 #include "audio_processor.h"
31 using std::stringstream;
37 using boost::optional;
38 using boost::shared_ptr;
40 AudioDecoder::AudioDecoder (shared_ptr<const AudioContent> content)
41 : _audio_content (content)
43 if (content->resampled_audio_frame_rate() != content->audio_frame_rate() && content->audio_channels ()) {
44 _resampler.reset (new Resampler (content->audio_frame_rate(), content->resampled_audio_frame_rate(), content->audio_channels ()));
47 if (content->audio_processor ()) {
48 _processor = content->audio_processor()->clone (content->resampled_audio_frame_rate ());
51 reset_decoded_audio ();
55 AudioDecoder::reset_decoded_audio ()
57 _decoded_audio = ContentAudio (shared_ptr<AudioBuffers> (new AudioBuffers (_audio_content->processed_audio_channels(), 0)), 0);
60 shared_ptr<ContentAudio>
61 AudioDecoder::get_audio (AudioFrame frame, AudioFrame length, bool accurate)
63 shared_ptr<ContentAudio> dec;
65 AudioFrame const end = frame + length - 1;
67 if (frame < _decoded_audio.frame || end > (_decoded_audio.frame + length * 4)) {
68 /* Either we have no decoded data, or what we do have is a long way from what we want: seek */
69 seek (ContentTime::from_frames (frame, _audio_content->audio_frame_rate()), accurate);
72 /* Offset of the data that we want from the start of _decoded_audio.audio
73 (to be set up shortly)
75 AudioFrame decoded_offset = 0;
77 /* Now enough pass() calls will either:
78 * (a) give us what we want, or
79 * (b) hit the end of the decoder.
81 * If we are being accurate, we want the right frames,
82 * otherwise any frames will do.
85 /* Keep stuffing data into _decoded_audio until we have enough data, or the subclass does not want to give us any more */
86 while (!pass() && (_decoded_audio.frame > frame || (_decoded_audio.frame + _decoded_audio.audio->frames()) < end)) {}
87 decoded_offset = frame - _decoded_audio.frame;
89 while (!pass() && _decoded_audio.audio->frames() < length) {}
90 /* Use decoded_offset of 0, as we don't really care what frames we return */
93 /* The amount of data available in _decoded_audio.audio starting from `frame'. This could be -ve
94 if pass() returned true before we got enough data.
96 AudioFrame const available = _decoded_audio.audio->frames() - decoded_offset;
98 /* We will return either that, or the requested amount, whichever is smaller */
99 AudioFrame const to_return = max ((AudioFrame) 0, min (available, length));
101 /* Copy our data to the output */
102 shared_ptr<AudioBuffers> out (new AudioBuffers (_decoded_audio.audio->channels(), to_return));
103 out->copy_from (_decoded_audio.audio.get(), to_return, decoded_offset, 0);
105 AudioFrame const remaining = max ((AudioFrame) 0, available - to_return);
107 /* Clean up decoded; first, move the data after what we just returned to the start of the buffer */
108 _decoded_audio.audio->move (decoded_offset + to_return, 0, remaining);
109 /* And set up the number of frames we have left */
110 _decoded_audio.audio->set_frames (remaining);
111 /* Also bump where those frames are in terms of the content */
112 _decoded_audio.frame += decoded_offset + to_return;
114 return shared_ptr<ContentAudio> (new ContentAudio (out, frame));
117 /** Called by subclasses when audio data is ready.
119 * Audio timestamping is made hard by many factors, but perhaps the most entertaining is resampling.
120 * We have to assume that we are feeding continuous data into the resampler, and so we get continuous
121 * data out. Hence we do the timestamping here, post-resampler, just by counting samples.
123 * The time is passed in here so that after a seek we can set up our _audio_position. The
124 * time is ignored once this has been done.
127 AudioDecoder::audio (shared_ptr<const AudioBuffers> data, ContentTime time)
130 data = _resampler->run (data);
134 data = _processor->run (data);
137 AudioFrame const frame_rate = _audio_content->resampled_audio_frame_rate ();
139 if (_seek_reference) {
140 /* We've had an accurate seek and now we're seeing some data */
141 ContentTime const delta = time - _seek_reference.get ();
142 AudioFrame const delta_frames = delta.frames (frame_rate);
143 if (delta_frames > 0) {
144 /* This data comes after the seek time. Pad the data with some silence. */
145 shared_ptr<AudioBuffers> padded (new AudioBuffers (data->channels(), data->frames() + delta_frames));
146 padded->make_silent ();
147 padded->copy_from (data.get(), data->frames(), 0, delta_frames);
150 } else if (delta_frames < 0) {
151 /* This data comes before the seek time. Throw some data away */
152 AudioFrame const to_discard = min (-delta_frames, static_cast<AudioFrame> (data->frames()));
153 AudioFrame const to_keep = data->frames() - to_discard;
155 /* We have to throw all this data away, so keep _seek_reference and
156 try again next time some data arrives.
160 shared_ptr<AudioBuffers> trimmed (new AudioBuffers (data->channels(), to_keep));
161 trimmed->copy_from (data.get(), to_keep, to_discard, 0);
163 time += ContentTime::from_frames (to_discard, frame_rate);
165 _seek_reference = optional<ContentTime> ();
168 if (!_audio_position) {
169 _audio_position = time.frames (frame_rate);
172 assert (_audio_position.get() >= (_decoded_audio.frame + _decoded_audio.audio->frames()));
174 /* Resize _decoded_audio to fit the new data */
176 if (_decoded_audio.audio->frames() == 0) {
177 /* There's nothing in there, so just store the new data */
178 new_size = data->frames ();
179 _decoded_audio.frame = _audio_position.get ();
181 /* Otherwise we need to extend _decoded_audio to include the new stuff */
182 new_size = _audio_position.get() + data->frames() - _decoded_audio.frame;
185 _decoded_audio.audio->ensure_size (new_size);
186 _decoded_audio.audio->set_frames (new_size);
188 /* Copy new data in */
189 _decoded_audio.audio->copy_from (data.get(), data->frames(), 0, _audio_position.get() - _decoded_audio.frame);
190 _audio_position = _audio_position.get() + data->frames ();
195 AudioDecoder::flush ()
202 shared_ptr<const AudioBuffers> b = _resampler->flush ();
204 _pending.push_back (shared_ptr<DecodedAudio> (new DecodedAudio (b, _audio_position.get ())));
205 _audio_position = _audio_position.get() + b->frames ();
211 AudioDecoder::seek (ContentTime t, bool accurate)
213 _audio_position.reset ();
214 reset_decoded_audio ();
219 _processor->flush ();