source/modules/juce_audio_formats/format/juce_AudioFormatReader.h

   1 /*
   2   ==============================================================================
   3
   4    This file is part of the JUCE library.
   5    Copyright (c) 2022 - Raw Material Software Limited
   6
   7    JUCE is an open source library subject to commercial or open-source
   8    licensing.
   9
  10    By using JUCE, you agree to the terms of both the JUCE 7 End-User License
  11    Agreement and JUCE Privacy Policy.
  12
  13    End User License Agreement: www.juce.com/juce-7-licence
  14    Privacy Policy: www.juce.com/juce-privacy-policy
  15
  16    Or: You may also use this code under the terms of the GPL v3 (see
  17    www.gnu.org/licenses).
  18
  19    JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
  20    EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
  21    DISCLAIMED.
  22
  23   ==============================================================================
  24 */
  25
  26 namespace juce
  27 {
  28
  29 class AudioFormat;
  30
  31
  32 //==============================================================================
  33 /**
  34     Reads samples from an audio file stream.
  35
  36     A subclass that reads a specific type of audio format will be created by
  37     an AudioFormat object.
  38
  39     @see AudioFormat, AudioFormatWriter
  40
  41     @tags{Audio}
  42 */
  43 class JUCE_API  AudioFormatReader
  44 {
  45 protected:
  46     //==============================================================================
  47     /** Creates an AudioFormatReader object.
  48
  49         @param sourceStream     the stream to read from - this will be deleted
  50                                 by this object when it is no longer needed. (Some
  51                                 specialised readers might not use this parameter and
  52                                 can leave it as nullptr).
  53         @param formatName       the description that will be returned by the getFormatName()
  54                                 method
  55     */
  56     AudioFormatReader (InputStream* sourceStream,
  57                        const String& formatName);
  58
  59 public:
  60     /** Destructor. */
  61     virtual ~AudioFormatReader();
  62
  63     //==============================================================================
  64     /** Returns a description of what type of format this is.
  65
  66         E.g. "AIFF"
  67     */
  68     const String& getFormatName() const noexcept    { return formatName; }
  69
  70     //==============================================================================
  71     /** Reads samples from the stream.
  72
  73         @param destChannels         an array of float buffers into which the sample data for each
  74                                     channel will be written. Channels that aren't needed can be null
  75         @param numDestChannels      the number of array elements in the destChannels array
  76         @param startSampleInSource  the position in the audio file or stream at which the samples
  77                                     should be read, as a number of samples from the start of the
  78                                     stream. It's ok for this to be beyond the start or end of the
  79                                     available data - any samples that are out-of-range will be returned
  80                                     as zeros.
  81         @param numSamplesToRead     the number of samples to read. If this is greater than the number
  82                                     of samples that the file or stream contains. the result will be padded
  83                                     with zeros
  84         @returns                    true if the operation succeeded, false if there was an error. Note
  85                                     that reading sections of data beyond the extent of the stream isn't an
  86                                     error - the reader should just return zeros for these regions
  87         @see readMaxLevels
  88     */
  89     bool read (float* const* destChannels, int numDestChannels,
  90                int64 startSampleInSource, int numSamplesToRead);
  91
  92     /** Reads samples from the stream.
  93
  94         @param destChannels         an array of buffers into which the sample data for each
  95                                     channel will be written.
  96                                     If the format is fixed-point, each channel will be written
  97                                     as an array of 32-bit signed integers using the full
  98                                     range -0x80000000 to 0x7fffffff, regardless of the source's
  99                                     bit-depth. If it is a floating-point format, you should cast
 100                                     the resulting array to a (float**) to get the values (in the
 101                                     range -1.0 to 1.0 or beyond)
 102                                     If the format is stereo, then destChannels[0] is the left channel
 103                                     data, and destChannels[1] is the right channel.
 104                                     The numDestChannels parameter indicates how many pointers this array
 105                                     contains, but some of these pointers can be null if you don't want to
 106                                     read data for some of the channels
 107         @param numDestChannels      the number of array elements in the destChannels array
 108         @param startSampleInSource  the position in the audio file or stream at which the samples
 109                                     should be read, as a number of samples from the start of the
 110                                     stream. It's ok for this to be beyond the start or end of the
 111                                     available data - any samples that are out-of-range will be returned
 112                                     as zeros.
 113         @param numSamplesToRead     the number of samples to read. If this is greater than the number
 114                                     of samples that the file or stream contains. the result will be padded
 115                                     with zeros
 116         @param fillLeftoverChannelsWithCopies   if true, this indicates that if there's no source data available
 117                                     for some of the channels that you pass in, then they should be filled with
 118                                     copies of valid source channels.
 119                                     E.g. if you're reading a mono file and you pass 2 channels to this method, then
 120                                     if fillLeftoverChannelsWithCopies is true, both destination channels will be filled
 121                                     with the same data from the file's single channel. If fillLeftoverChannelsWithCopies
 122                                     was false, then only the first channel would be filled with the file's contents, and
 123                                     the second would be cleared. If there are many channels, e.g. you try to read 4 channels
 124                                     from a stereo file, then the last 3 would all end up with copies of the same data.
 125         @returns                    true if the operation succeeded, false if there was an error. Note
 126                                     that reading sections of data beyond the extent of the stream isn't an
 127                                     error - the reader should just return zeros for these regions
 128         @see readMaxLevels
 129     */
 130     bool read (int* const* destChannels,
 131                int numDestChannels,
 132                int64 startSampleInSource,
 133                int numSamplesToRead,
 134                bool fillLeftoverChannelsWithCopies);
 135
 136     /** Fills a section of an AudioBuffer from this reader.
 137
 138         This will convert the reader's fixed- or floating-point data to
 139         the buffer's floating-point format, and will try to intelligently
 140         cope with mismatches between the number of channels in the reader
 141         and the buffer.
 142
 143         @returns    true if the operation succeeded, false if there was an error. Note
 144                     that reading sections of data beyond the extent of the stream isn't an
 145                     error - the reader should just return zeros for these regions
 146     */
 147     bool read (AudioBuffer<float>* buffer,
 148                int startSampleInDestBuffer,
 149                int numSamples,
 150                int64 readerStartSample,
 151                bool useReaderLeftChan,
 152                bool useReaderRightChan);
 153
 154     /** Finds the highest and lowest sample levels from a section of the audio stream.
 155
 156         This will read a block of samples from the stream, and measure the
 157         highest and lowest sample levels from the channels in that section, returning
 158         these as normalised floating-point levels.
 159
 160         @param startSample  the offset into the audio stream to start reading from. It's
 161                             ok for this to be beyond the start or end of the stream.
 162         @param numSamples   how many samples to read
 163         @param results      this array will be filled with Range values for each channel.
 164                             The array must contain numChannels elements.
 165         @param numChannelsToRead  the number of channels of data to scan. This must be
 166                             more than zero, but not more than the total number of channels
 167                             that the reader contains
 168         @see read
 169     */
 170     virtual void readMaxLevels (int64 startSample, int64 numSamples,
 171                                 Range<float>* results, int numChannelsToRead);
 172
 173     /** Finds the highest and lowest sample levels from a section of the audio stream.
 174
 175         This will read a block of samples from the stream, and measure the
 176         highest and lowest sample levels from the channels in that section, returning
 177         these as normalised floating-point levels.
 178
 179         @param startSample          the offset into the audio stream to start reading from. It's
 180                                     ok for this to be beyond the start or end of the stream.
 181         @param numSamples           how many samples to read
 182         @param lowestLeft           on return, this is the lowest absolute sample from the left channel
 183         @param highestLeft          on return, this is the highest absolute sample from the left channel
 184         @param lowestRight          on return, this is the lowest absolute sample from the right
 185                                     channel (if there is one)
 186         @param highestRight         on return, this is the highest absolute sample from the right
 187                                     channel (if there is one)
 188         @see read
 189     */
 190     virtual void readMaxLevels (int64 startSample, int64 numSamples,
 191                                 float& lowestLeft,  float& highestLeft,
 192                                 float& lowestRight, float& highestRight);
 193
 194     /** Scans the source looking for a sample whose magnitude is in a specified range.
 195
 196         This will read from the source, either forwards or backwards between two sample
 197         positions, until it finds a sample whose magnitude lies between two specified levels.
 198
 199         If it finds a suitable sample, it returns its position; if not, it will return -1.
 200
 201         There's also a minimumConsecutiveSamples setting to help avoid spikes or zero-crossing
 202         points when you're searching for a continuous range of samples
 203
 204         @param startSample              the first sample to look at
 205         @param numSamplesToSearch       the number of samples to scan. If this value is negative,
 206                                         the search will go backwards
 207         @param magnitudeRangeMinimum    the lowest magnitude (inclusive) that is considered a hit, from 0 to 1.0
 208         @param magnitudeRangeMaximum    the highest magnitude (inclusive) that is considered a hit, from 0 to 1.0
 209         @param minimumConsecutiveSamples    if this is > 0, the method will only look for a sequence
 210                                             of this many consecutive samples, all of which lie
 211                                             within the target range. When it finds such a sequence,
 212                                             it returns the position of the first in-range sample
 213                                             it found (i.e. the earliest one if scanning forwards, the
 214                                             latest one if scanning backwards)
 215     */
 216     int64 searchForLevel (int64 startSample,
 217                           int64 numSamplesToSearch,
 218                           double magnitudeRangeMinimum,
 219                           double magnitudeRangeMaximum,
 220                           int minimumConsecutiveSamples);
 221
 222
 223     //==============================================================================
 224     /** The sample-rate of the stream. */
 225     double sampleRate = 0;
 226
 227     /** The number of bits per sample, e.g. 16, 24, 32. */
 228     unsigned int bitsPerSample = 0;
 229
 230     /** The total number of samples in the audio stream. */
 231     int64 lengthInSamples = 0;
 232
 233     /** The total number of channels in the audio stream. */
 234     unsigned int numChannels = 0;
 235
 236     /** Indicates whether the data is floating-point or fixed. */
 237     bool usesFloatingPointData = false;
 238
 239     /** A set of metadata values that the reader has pulled out of the stream.
 240
 241         Exactly what these values are depends on the format, so you can
 242         check out the format implementation code to see what kind of stuff
 243         they understand.
 244     */
 245     StringPairArray metadataValues;
 246
 247     /** The input stream, for use by subclasses. */
 248     InputStream* input;
 249
 250     //==============================================================================
 251     /** Get the channel layout of the audio stream. */
 252     virtual AudioChannelSet getChannelLayout();
 253
 254     //==============================================================================
 255     /** Subclasses must implement this method to perform the low-level read operation.
 256
 257         Callers should use read() instead of calling this directly.
 258
 259         @param destChannels              the array of destination buffers to fill. Some of these
 260                                          pointers may be null
 261         @param numDestChannels           the number of items in the destChannels array. This
 262                                          value is guaranteed not to be greater than the number of
 263                                          channels that this reader object contains
 264         @param startOffsetInDestBuffer   the number of samples from the start of the
 265                                          dest data at which to begin writing
 266         @param startSampleInFile         the number of samples into the source data at which
 267                                          to begin reading. This value is guaranteed to be >= 0.
 268         @param numSamples                the number of samples to read
 269     */
 270     virtual bool readSamples (int** destChannels,
 271                               int numDestChannels,
 272                               int startOffsetInDestBuffer,
 273                               int64 startSampleInFile,
 274                               int numSamples) = 0;
 275
 276
 277 protected:
 278     //==============================================================================
 279     /** Used by AudioFormatReader subclasses to copy data to different formats. */
 280     template <class DestSampleType, class SourceSampleType, class SourceEndianness>
 281     struct ReadHelper
 282     {
 283         using DestType   = AudioData::Pointer<DestSampleType,   AudioData::NativeEndian, AudioData::NonInterleaved, AudioData::NonConst>;
 284         using SourceType = AudioData::Pointer<SourceSampleType, SourceEndianness, AudioData::Interleaved, AudioData::Const>;
 285
 286         template <typename TargetType>
 287         static void read (TargetType* const* destData, int destOffset, int numDestChannels,
 288                           const void* sourceData, int numSourceChannels, int numSamples) noexcept
 289         {
 290             for (int i = 0; i < numDestChannels; ++i)
 291             {
 292                 if (void* targetChan = destData[i])
 293                 {
 294                     DestType dest (targetChan);
 295                     dest += destOffset;
 296
 297                     if (i < numSourceChannels)
 298                         dest.convertSamples (SourceType (addBytesToPointer (sourceData, i * SourceType::getBytesPerSample()), numSourceChannels), numSamples);
 299                     else
 300                         dest.clearSamples (numSamples);
 301                 }
 302             }
 303         }
 304     };
 305
 306     /** Used by AudioFormatReader subclasses to clear any parts of the data blocks that lie
 307         beyond the end of their available length.
 308     */
 309     static void clearSamplesBeyondAvailableLength (int** destChannels, int numDestChannels,
 310                                                    int startOffsetInDestBuffer, int64 startSampleInFile,
 311                                                    int& numSamples, int64 fileLengthInSamples)
 312     {
 313         if (destChannels == nullptr)
 314         {
 315             jassertfalse;
 316             return;
 317         }
 318
 319         const int64 samplesAvailable = fileLengthInSamples - startSampleInFile;
 320
 321         if (samplesAvailable < numSamples)
 322         {
 323             for (int i = numDestChannels; --i >= 0;)
 324                 if (destChannels[i] != nullptr)
 325                     zeromem (destChannels[i] + startOffsetInDestBuffer, (size_t) numSamples * sizeof (int));
 326
 327             numSamples = (int) samplesAvailable;
 328         }
 329     }
 330
 331 private:
 332     String formatName;
 333
 334     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AudioFormatReader)
 335 };
 336
 337 } // namespace juce