Makes it easy to quickly draw scaled views of the waveform shape of an audio file. More...
Inherits ChangeBroadcaster.
Public Member Functions | |
| AudioThumbnail (int sourceSamplesPerThumbnailSample, AudioFormatManager &formatManagerToUse, AudioThumbnailCache &cacheToUse) | |
| Creates an audio thumbnail. | |
| ~AudioThumbnail () | |
| Destructor. | |
| void | clear () |
| Clears and resets the thumbnail. | |
| bool | setSource (InputSource *newSource) |
| Specifies the file or stream that contains the audio file. | |
| void | setReader (AudioFormatReader *newReader, int64 hashCode) |
| Gives the thumbnail an AudioFormatReader to use directly. | |
| void | reset (int numChannels, double sampleRate, int64 totalSamplesInSource=0) |
| Resets the thumbnail, ready for adding data with the specified format. | |
| void | addBlock (int64 sampleNumberInSource, const AudioSampleBuffer &newData, int startOffsetInBuffer, int numSamples) |
| Adds a block of level data to the thumbnail. | |
| void | loadFrom (InputStream &input) |
| Reloads the low res thumbnail data from an input stream. | |
| void | saveTo (OutputStream &output) const |
| Saves the low res thumbnail data to an output stream. | |
| int | getNumChannels () const noexcept |
| Returns the number of channels in the file. | |
| double | getTotalLength () const noexcept |
| Returns the length of the audio file, in seconds. | |
| void | drawChannel (Graphics &g, const Rectangle< int > &area, double startTimeSeconds, double endTimeSeconds, int channelNum, float verticalZoomFactor) |
| Draws the waveform for a channel. | |
| void | drawChannels (Graphics &g, const Rectangle< int > &area, double startTimeSeconds, double endTimeSeconds, float verticalZoomFactor) |
| Draws the waveforms for all channels in the thumbnail. | |
| bool | isFullyLoaded () const noexcept |
| Returns true if the low res preview is fully generated. | |
| int64 | getNumSamplesFinished () const noexcept |
| Returns the number of samples that have been set in the thumbnail. | |
| float | getApproximatePeak () const |
| Returns the highest level in the thumbnail. | |
| void | getApproximateMinMax (double startTime, double endTime, int channelIndex, float &minValue, float &maxValue) const noexcept |
| Reads the approximate min and max levels from a section of the thumbnail. | |
| int64 | getHashCode () const |
| Returns the hash code that was set by setSource() or setReader(). | |
Makes it easy to quickly draw scaled views of the waveform shape of an audio file.
To use this class, just create an AudioThumbNail class for the file you want to draw, call setSource to tell it which file or resource to use, then call drawChannel() to draw it.
The class will asynchronously scan the wavefile to create its scaled-down view, so you should make your UI repaint itself as this data comes in. To do this, the AudioThumbnail is a ChangeBroadcaster, and will broadcast a message when its listeners should repaint themselves.
The thumbnail stores an internal low-res version of the wave data, and this can be loaded and saved to avoid having to scan the file again.
| AudioThumbnail::AudioThumbnail | ( | int | sourceSamplesPerThumbnailSample, |
| AudioFormatManager & | formatManagerToUse, | ||
| AudioThumbnailCache & | cacheToUse | ||
| ) |
Creates an audio thumbnail.
| sourceSamplesPerThumbnailSample | when creating a stored, low-res version of the audio data, this is the scale at which it should be done. (This number is the number of original samples that will be averaged for each low-res sample) |
| formatManagerToUse | the audio format manager that is used to open the file |
| cacheToUse | an instance of an AudioThumbnailCache - this provides a background thread and storage that is used to by the thumbnail, and the cache object can be shared between multiple thumbnails |
| AudioThumbnail::~AudioThumbnail | ( | ) |
Destructor.
| void AudioThumbnail::clear | ( | ) |
Clears and resets the thumbnail.
| bool AudioThumbnail::setSource | ( | InputSource * | newSource ) |
Specifies the file or stream that contains the audio file.
For a file, just call
setSource (new FileInputSource (file))
You can pass a zero in here to clear the thumbnail. The source that is passed in will be deleted by this object when it is no longer needed.
| void AudioThumbnail::setReader | ( | AudioFormatReader * | newReader, |
| int64 | hashCode | ||
| ) |
Gives the thumbnail an AudioFormatReader to use directly.
This will start parsing the audio in a background thread (unless the hash code can be looked-up successfully in the thumbnail cache). Note that the reader object will be held by the thumbnail and deleted later when no longer needed. The thumbnail will actually keep hold of this reader until you clear the thumbnail or change the input source, so the file will be held open for all this time. If you don't want the thumbnail to keep a file handle open continuously, you should use the setSource() method instead, which will only open the file when it needs to.
| void AudioThumbnail::reset | ( | int | numChannels, |
| double | sampleRate, | ||
| int64 | totalSamplesInSource = 0 |
||
| ) |
Resets the thumbnail, ready for adding data with the specified format.
If you're going to generate a thumbnail yourself, call this before using addBlock() to add the data.
| void AudioThumbnail::addBlock | ( | int64 | sampleNumberInSource, |
| const AudioSampleBuffer & | newData, | ||
| int | startOffsetInBuffer, | ||
| int | numSamples | ||
| ) |
Adds a block of level data to the thumbnail.
Call reset() before using this, to tell the thumbnail about the data format.
| void AudioThumbnail::loadFrom | ( | InputStream & | input ) |
| void AudioThumbnail::saveTo | ( | OutputStream & | output ) | const |
Saves the low res thumbnail data to an output stream.
The data that is written can later be reloaded using loadFrom().
| int AudioThumbnail::getNumChannels | ( | ) | const |
Returns the number of channels in the file.
| double AudioThumbnail::getTotalLength | ( | ) | const |
Returns the length of the audio file, in seconds.
| void AudioThumbnail::drawChannel | ( | Graphics & | g, |
| const Rectangle< int > & | area, | ||
| double | startTimeSeconds, | ||
| double | endTimeSeconds, | ||
| int | channelNum, | ||
| float | verticalZoomFactor | ||
| ) |
Draws the waveform for a channel.
The waveform will be drawn within the specified rectangle, where startTime and endTime specify the times within the audio file that should be positioned at the left and right edges of the rectangle.
The waveform will be scaled vertically so that a full-volume sample will fill the rectangle vertically, but you can also specify an extra vertical scale factor with the verticalZoomFactor parameter.
| void AudioThumbnail::drawChannels | ( | Graphics & | g, |
| const Rectangle< int > & | area, | ||
| double | startTimeSeconds, | ||
| double | endTimeSeconds, | ||
| float | verticalZoomFactor | ||
| ) |
Draws the waveforms for all channels in the thumbnail.
This will call drawChannel() to render each of the thumbnail's channels, stacked above each other within the specified area.
| bool AudioThumbnail::isFullyLoaded | ( | ) | const |
Returns true if the low res preview is fully generated.
| int64 AudioThumbnail::getNumSamplesFinished | ( | ) | const |
Returns the number of samples that have been set in the thumbnail.
| float AudioThumbnail::getApproximatePeak | ( | ) | const |
Returns the highest level in the thumbnail.
Note that because the thumb only stores low-resolution data, this isn't an accurate representation of the highest value, it's only a rough approximation.
| void AudioThumbnail::getApproximateMinMax | ( | double | startTime, |
| double | endTime, | ||
| int | channelIndex, | ||
| float & | minValue, | ||
| float & | maxValue | ||
| ) | const |
Reads the approximate min and max levels from a section of the thumbnail.
The lowest and highest samples are returned in minValue and maxValue, but obviously because the thumb only stores low-resolution data, these numbers will only be a rough approximation of the true values.
| int64 AudioThumbnail::getHashCode | ( | ) | const |
Returns the hash code that was set by setSource() or setReader().
