1 // Copyright (c) 2016 The WebM project authors. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the LICENSE file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS.  All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 #ifndef SRC_AUDIO_PARSER_H_
9 #define SRC_AUDIO_PARSER_H_
10 
11 #include <cassert>
12 #include <cstdint>
13 
14 #include "src/float_parser.h"
15 #include "src/int_parser.h"
16 #include "src/master_value_parser.h"
17 #include "webm/callback.h"
18 #include "webm/dom_types.h"
19 #include "webm/id.h"
20 #include "webm/reader.h"
21 #include "webm/status.h"
22 
23 namespace webm {
24 
25 // Spec reference:
26 // http://matroska.org/technical/specs/index.html#Audio
27 // http://www.webmproject.org/docs/container/#Audio
28 class AudioParser : public MasterValueParser<Audio> {
29  public:
AudioParser()30   AudioParser()
31       : MasterValueParser<Audio>(
32             MakeChild<FloatParser>(Id::kSamplingFrequency,
33                                    &Audio::sampling_frequency),
34             MakeChild<FloatParser>(Id::kOutputSamplingFrequency,
35                                    &Audio::output_frequency)
36                 .NotifyOnParseComplete(),
37             MakeChild<UnsignedIntParser>(Id::kChannels, &Audio::channels),
38             MakeChild<UnsignedIntParser>(Id::kBitDepth, &Audio::bit_depth)) {}
39 
Init(const ElementMetadata & metadata,std::uint64_t max_size)40   Status Init(const ElementMetadata& metadata,
41               std::uint64_t max_size) override {
42     output_frequency_has_value_ = false;
43 
44     return MasterValueParser::Init(metadata, max_size);
45   }
46 
InitAfterSeek(const Ancestory & child_ancestory,const ElementMetadata & child_metadata)47   void InitAfterSeek(const Ancestory& child_ancestory,
48                      const ElementMetadata& child_metadata) override {
49     output_frequency_has_value_ = false;
50 
51     return MasterValueParser::InitAfterSeek(child_ancestory, child_metadata);
52   }
53 
Feed(Callback * callback,Reader * reader,std::uint64_t * num_bytes_read)54   Status Feed(Callback* callback, Reader* reader,
55               std::uint64_t* num_bytes_read) override {
56     const Status status =
57         MasterValueParser::Feed(callback, reader, num_bytes_read);
58     if (status.completed_ok()) {
59       FixMissingOutputFrequency();
60     }
61     return status;
62   }
63 
64  protected:
OnChildParsed(const ElementMetadata & metadata)65   void OnChildParsed(const ElementMetadata& metadata) override {
66     assert(metadata.id == Id::kOutputSamplingFrequency);
67 
68     output_frequency_has_value_ = metadata.size > 0;
69   }
70 
71  private:
72   bool output_frequency_has_value_;
73 
FixMissingOutputFrequency()74   void FixMissingOutputFrequency() {
75     if (!output_frequency_has_value_) {
76       *mutable_value()->output_frequency.mutable_value() =
77           value().sampling_frequency.value();
78     }
79   }
80 };
81 
82 }  // namespace webm
83 
84 #endif  // SRC_AUDIO_PARSER_H_
85