OpenShot Library | libopenshot-audio  0.1.9
juce_AudioFormatReader.h
1 
2 /** @weakgroup juce_audio_formats-format
3  * @{
4  */
5 /*
6  ==============================================================================
7 
8  This file is part of the JUCE library.
9  Copyright (c) 2017 - ROLI Ltd.
10 
11  JUCE is an open source library subject to commercial or open-source
12  licensing.
13 
14  By using JUCE, you agree to the terms of both the JUCE 5 End-User License
15  Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
16  27th April 2017).
17 
18  End User License Agreement: www.juce.com/juce-5-licence
19  Privacy Policy: www.juce.com/juce-5-privacy-policy
20 
21  Or: You may also use this code under the terms of the GPL v3 (see
22  www.gnu.org/licenses).
23 
24  JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
25  EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
26  DISCLAIMED.
27 
28  ==============================================================================
29 */
30 
31 namespace juce
32 {
33 
34 class AudioFormat;
35 
36 
37 //==============================================================================
38 /**
39  Reads samples from an audio file stream.
40 
41  A subclass that reads a specific type of audio format will be created by
42  an AudioFormat object.
43 
44  @see AudioFormat, AudioFormatWriter
45 
46  @tags{Audio}
47 */
49 {
50 protected:
51  //==============================================================================
52  /** Creates an AudioFormatReader object.
53 
54  @param sourceStream the stream to read from - this will be deleted
55  by this object when it is no longer needed. (Some
56  specialised readers might not use this parameter and
57  can leave it as nullptr).
58  @param formatName the description that will be returned by the getFormatName()
59  method
60  */
61  AudioFormatReader (InputStream* sourceStream,
62  const String& formatName);
63 
64 public:
65  /** Destructor. */
66  virtual ~AudioFormatReader();
67 
68  //==============================================================================
69  /** Returns a description of what type of format this is.
70 
71  E.g. "AIFF"
72  */
73  const String& getFormatName() const noexcept { return formatName; }
74 
75  //==============================================================================
76  /** Reads samples from the stream.
77 
78  @param destChannels an array of float buffers into which the sample data for each
79  channel will be written. Channels that aren't needed can be null
80  @param numDestChannels the number of array elements in the destChannels array
81  @param startSampleInSource the position in the audio file or stream at which the samples
82  should be read, as a number of samples from the start of the
83  stream. It's ok for this to be beyond the start or end of the
84  available data - any samples that are out-of-range will be returned
85  as zeros.
86  @param numSamplesToRead the number of samples to read. If this is greater than the number
87  of samples that the file or stream contains. the result will be padded
88  with zeros
89  @returns true if the operation succeeded, false if there was an error. Note
90  that reading sections of data beyond the extent of the stream isn't an
91  error - the reader should just return zeros for these regions
92  @see readMaxLevels
93  */
94  bool read (float* const* destChannels, int numDestChannels,
95  int64 startSampleInSource, int numSamplesToRead);
96 
97  /** Reads samples from the stream.
98 
99  @param destChannels an array of buffers into which the sample data for each
100  channel will be written.
101  If the format is fixed-point, each channel will be written
102  as an array of 32-bit signed integers using the full
103  range -0x80000000 to 0x7fffffff, regardless of the source's
104  bit-depth. If it is a floating-point format, you should cast
105  the resulting array to a (float**) to get the values (in the
106  range -1.0 to 1.0 or beyond)
107  If the format is stereo, then destChannels[0] is the left channel
108  data, and destChannels[1] is the right channel.
109  The numDestChannels parameter indicates how many pointers this array
110  contains, but some of these pointers can be null if you don't want to
111  read data for some of the channels
112  @param numDestChannels the number of array elements in the destChannels array
113  @param startSampleInSource the position in the audio file or stream at which the samples
114  should be read, as a number of samples from the start of the
115  stream. It's ok for this to be beyond the start or end of the
116  available data - any samples that are out-of-range will be returned
117  as zeros.
118  @param numSamplesToRead the number of samples to read. If this is greater than the number
119  of samples that the file or stream contains. the result will be padded
120  with zeros
121  @param fillLeftoverChannelsWithCopies if true, this indicates that if there's no source data available
122  for some of the channels that you pass in, then they should be filled with
123  copies of valid source channels.
124  E.g. if you're reading a mono file and you pass 2 channels to this method, then
125  if fillLeftoverChannelsWithCopies is true, both destination channels will be filled
126  with the same data from the file's single channel. If fillLeftoverChannelsWithCopies
127  was false, then only the first channel would be filled with the file's contents, and
128  the second would be cleared. If there are many channels, e.g. you try to read 4 channels
129  from a stereo file, then the last 3 would all end up with copies of the same data.
130  @returns true if the operation succeeded, false if there was an error. Note
131  that reading sections of data beyond the extent of the stream isn't an
132  error - the reader should just return zeros for these regions
133  @see readMaxLevels
134  */
135  bool read (int* const* destChannels,
136  int numDestChannels,
137  int64 startSampleInSource,
138  int numSamplesToRead,
139  bool fillLeftoverChannelsWithCopies);
140 
141  /** Fills a section of an AudioBuffer from this reader.
142 
143  This will convert the reader's fixed- or floating-point data to
144  the buffer's floating-point format, and will try to intelligently
145  cope with mismatches between the number of channels in the reader
146  and the buffer.
147  */
148  void read (AudioBuffer<float>* buffer,
149  int startSampleInDestBuffer,
150  int numSamples,
151  int64 readerStartSample,
152  bool useReaderLeftChan,
153  bool useReaderRightChan);
154 
155  /** Finds the highest and lowest sample levels from a section of the audio stream.
156 
157  This will read a block of samples from the stream, and measure the
158  highest and lowest sample levels from the channels in that section, returning
159  these as normalised floating-point levels.
160 
161  @param startSample the offset into the audio stream to start reading from. It's
162  ok for this to be beyond the start or end of the stream.
163  @param numSamples how many samples to read
164  @param results this array will be filled with Range values for each channel.
165  The array must contain numChannels elements.
166  @param numChannelsToRead the number of channels of data to scan. This must be
167  more than zero, but not more than the total number of channels
168  that the reader contains
169  @see read
170  */
171  virtual void readMaxLevels (int64 startSample, int64 numSamples,
172  Range<float>* results, int numChannelsToRead);
173 
174  /** Finds the highest and lowest sample levels from a section of the audio stream.
175 
176  This will read a block of samples from the stream, and measure the
177  highest and lowest sample levels from the channels in that section, returning
178  these as normalised floating-point levels.
179 
180  @param startSample the offset into the audio stream to start reading from. It's
181  ok for this to be beyond the start or end of the stream.
182  @param numSamples how many samples to read
183  @param lowestLeft on return, this is the lowest absolute sample from the left channel
184  @param highestLeft on return, this is the highest absolute sample from the left channel
185  @param lowestRight on return, this is the lowest absolute sample from the right
186  channel (if there is one)
187  @param highestRight on return, this is the highest absolute sample from the right
188  channel (if there is one)
189  @see read
190  */
191  virtual void readMaxLevels (int64 startSample, int64 numSamples,
192  float& lowestLeft, float& highestLeft,
193  float& lowestRight, float& highestRight);
194 
195  /** Scans the source looking for a sample whose magnitude is in a specified range.
196 
197  This will read from the source, either forwards or backwards between two sample
198  positions, until it finds a sample whose magnitude lies between two specified levels.
199 
200  If it finds a suitable sample, it returns its position; if not, it will return -1.
201 
202  There's also a minimumConsecutiveSamples setting to help avoid spikes or zero-crossing
203  points when you're searching for a continuous range of samples
204 
205  @param startSample the first sample to look at
206  @param numSamplesToSearch the number of samples to scan. If this value is negative,
207  the search will go backwards
208  @param magnitudeRangeMinimum the lowest magnitude (inclusive) that is considered a hit, from 0 to 1.0
209  @param magnitudeRangeMaximum the highest magnitude (inclusive) that is considered a hit, from 0 to 1.0
210  @param minimumConsecutiveSamples if this is > 0, the method will only look for a sequence
211  of this many consecutive samples, all of which lie
212  within the target range. When it finds such a sequence,
213  it returns the position of the first in-range sample
214  it found (i.e. the earliest one if scanning forwards, the
215  latest one if scanning backwards)
216  */
217  int64 searchForLevel (int64 startSample,
218  int64 numSamplesToSearch,
219  double magnitudeRangeMinimum,
220  double magnitudeRangeMaximum,
221  int minimumConsecutiveSamples);
222 
223 
224  //==============================================================================
225  /** The sample-rate of the stream. */
226  double sampleRate = 0;
227 
228  /** The number of bits per sample, e.g. 16, 24, 32. */
229  unsigned int bitsPerSample = 0;
230 
231  /** The total number of samples in the audio stream. */
232  int64 lengthInSamples = 0;
233 
234  /** The total number of channels in the audio stream. */
235  unsigned int numChannels = 0;
236 
237  /** Indicates whether the data is floating-point or fixed. */
238  bool usesFloatingPointData = false;
239 
240  /** A set of metadata values that the reader has pulled out of the stream.
241 
242  Exactly what these values are depends on the format, so you can
243  check out the format implementation code to see what kind of stuff
244  they understand.
245  */
247 
248  /** The input stream, for use by subclasses. */
250 
251  //==============================================================================
252  /** Get the channel layout of the audio stream. */
253  virtual AudioChannelSet getChannelLayout();
254 
255  //==============================================================================
256  /** Subclasses must implement this method to perform the low-level read operation.
257 
258  Callers should use read() instead of calling this directly.
259 
260  @param destChannels the array of destination buffers to fill. Some of these
261  pointers may be null
262  @param numDestChannels the number of items in the destChannels array. This
263  value is guaranteed not to be greater than the number of
264  channels that this reader object contains
265  @param startOffsetInDestBuffer the number of samples from the start of the
266  dest data at which to begin writing
267  @param startSampleInFile the number of samples into the source data at which
268  to begin reading. This value is guaranteed to be >= 0.
269  @param numSamples the number of samples to read
270  */
271  virtual bool readSamples (int** destChannels,
272  int numDestChannels,
273  int startOffsetInDestBuffer,
274  int64 startSampleInFile,
275  int numSamples) = 0;
276 
277 
278 protected:
279  //==============================================================================
280  /** Used by AudioFormatReader subclasses to copy data to different formats. */
281  template <class DestSampleType, class SourceSampleType, class SourceEndianness>
282  struct ReadHelper
283  {
286 
287  template <typename TargetType>
288  static void read (TargetType* const* destData, int destOffset, int numDestChannels,
289  const void* sourceData, int numSourceChannels, int numSamples) noexcept
290  {
291  for (int i = 0; i < numDestChannels; ++i)
292  {
293  if (void* targetChan = destData[i])
294  {
295  DestType dest (targetChan);
296  dest += destOffset;
297 
298  if (i < numSourceChannels)
299  dest.convertSamples (SourceType (addBytesToPointer (sourceData, i * SourceType::getBytesPerSample()), numSourceChannels), numSamples);
300  else
301  dest.clearSamples (numSamples);
302  }
303  }
304  }
305  };
306 
307  /** Used by AudioFormatReader subclasses to clear any parts of the data blocks that lie
308  beyond the end of their available length.
309  */
310  static void clearSamplesBeyondAvailableLength (int** destChannels, int numDestChannels,
311  int startOffsetInDestBuffer, int64 startSampleInFile,
312  int& numSamples, int64 fileLengthInSamples)
313  {
314  jassert (destChannels != nullptr);
315  const int64 samplesAvailable = fileLengthInSamples - startSampleInFile;
316 
317  if (samplesAvailable < numSamples)
318  {
319  for (int i = numDestChannels; --i >= 0;)
320  if (destChannels[i] != nullptr)
321  zeromem (destChannels[i] + startOffsetInDestBuffer, sizeof (int) * (size_t) numSamples);
322 
323  numSamples = (int) samplesAvailable;
324  }
325  }
326 
327 private:
328  String formatName;
329 
330  JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AudioFormatReader)
331 };
332 
333 } // namespace juce
334 
335 /** @}*/
static void clearSamplesBeyondAvailableLength(int **destChannels, int numDestChannels, int startOffsetInDestBuffer, int64 startSampleInFile, int &numSamples, int64 fileLengthInSamples)
Used by AudioFormatReader subclasses to clear any parts of the data blocks that lie beyond the end of...
Represents a set of audio channel types.
Used as a template parameter for AudioData::Pointer.
void clearSamples(int numSamples) const noexcept
Sets a number of samples to zero.
#define JUCE_API
This macro is added to all JUCE public class declarations.
The base class for streams that read data.
InputStream * input
The input stream, for use by subclasses.
const String & getFormatName() const noexcept
Returns a description of what type of format this is.
The JUCE String class!
Definition: juce_String.h:42
StringPairArray metadataValues
A set of metadata values that the reader has pulled out of the stream.
Used by AudioFormatReader subclasses to copy data to different formats.
void convertSamples(Pointer source, int numSamples) const noexcept
Writes a stream of samples into this pointer from another pointer.
A container for holding a set of strings which are keyed by another string.
Reads samples from an audio file stream.
A general-purpose range object, that simply represents any linear range with a start and end point...
Definition: juce_Range.h:43