Patent Application
20110011244
The following relates to computing devices capable of and methods for arranging music, and more particularly to approaches for adjusting a variable tempo of an audio file independent of a global tempo in a digital audio workstation.
Artists can use software to create musical arrangements. This software can be implemented on a computer to allow an artist to write, record, edit, and mix musical arrangements. Typically, such software can allow the artist to arrange files on musical tracks in a musical arrangement. A computer that includes the software can be referred to as a digital audio workstation (DAW). The DAW can display a graphical user interface (GUI) to allow a user to manipulate files on tracks. The DAW can display each element of a musical arrangement, such as a guitar, microphone, or drums, on separate tracks. For example, a user may create a musical arrangement with a guitar on a first track, a piano on a second track, and vocals on a third track. The DAW can further break down an instrument into multiple tracks. For example, a drum kit can be broken into multiple tracks with the snare, kick drum, and hi-hat each having its own track. By placing each element on a separate track a user is able to manipulate a single track, without affecting the other tracks. For example, a user can adjust the volume or pan of the guitar track, without affecting the piano track or vocal track. As will be appreciated by those of ordinary skill in the art, using the GUI, a user can apply different effects to a track within a musical arrangement. For example, volume, pan, compression, distortion, equalization, delay, and reverb are some of the effects that can be applied to a track.
Typically, a DAW works with two main types of files: MIDI (Musical Instrument Digital Interface) files and audio files. MIDI is an industry-standard protocol that enables electronic musical instruments, such as keyboard controllers, computers, and other electronic equipment, to communicate, control, and synchronize with each other. MIDI does not transmit an audio signal or media, but rather transmits “event messages” such as the pitch and intensity of musical notes to play, control signals for parameters such as volume, vibrato and panning, cues, and clock signals to set the tempo. As an electronic protocol, MIDI is notable for its widespread adoption throughout the industry.
Using a MIDI controller coupled to a computer, a user can record MIDI data into a MIDI track. Using the DAW, the user can select a MIDI instrument that is internal to a computer and/or an external MIDI instrument to generate sounds corresponding to the MIDI data of a MIDI track. The selected MIDI instrument can receive the MIDI data from the MIDI track and generate sounds corresponding to the MIDI data which can be produced by one or more monitors or speakers. For example, a user may select a piano software instrument on the computer to generate piano sounds and/or may select a tenor saxophone instrument on an external MIDI device to generate saxophone sounds corresponding to the MIDI data. If MIDI data from a track is sent to an internal software instrument, this track can be referred to as an internal track. If MIDI data from a track is sent to an external software instrument, this track can be referred to as an external track.
Audio files are recorded sounds. An audio file can be created by recording sound directly into the system. For example, a user may use a guitar to record directly onto a guitar track or record vocals, using a microphone, directly onto a vocal track. As will be appreciated by those of ordinary skill in the art, audio files can be imported into a musical arrangement. For example, many companies professionally produce audio files for incorporation into musical arrangements. In another example, audio files can be downloaded from the Internet. Audio files can include guitar riffs, drum loops, and any other recorded sounds. Audio files can be in sound digital file formats such as WAV, MP3, M4A, and AIFF. Audio files can also be recorded from analog sources, including, but not limited to, tapes and records.
Using the DAW, a user can make tempo changes to a musical composition. The tempo changes affect MIDI tracks and audio tracks differently. In MIDI files, tempo and pitch can be adjusted independently of each other. For example, a MIDI track recorded at 100 bpm (beats per minute) can be adjusted to 120 bpm without affecting the pitch of samples played by the MIDI data. This occurs because the same samples are being triggered by the MIDI data at a faster rate by a clock signal. However, tempo changes to an audio file inherently adjust the pitch of the file as well. For example, if an audio file is sped up, the pitch of the sound goes up. Conversley, if an audio file is slowed, the pitch of the sound goes down. Conventional DAWs can use a process known as time stretching to adjust the tempo of audio while maintaining the original pitch. This process requires analysis and processing of the original audio file. Those of ordinary skill in the art will recognize that various algorithms and methods for adjusting the tempo of audio files while maintaining a consistent pitch can be used.
Conventional DAWs are limited in that a musical arrangement typically has a global tempo. In a conventional DAW, MIDI and audio files follow this global tempo. Conventional DAWs do not provide an audio file having a variable tempo that is independent of the global tempo of the musical arrangement. Similarly, conventional DAWs do not provide a graphical interface to set an intital tempo, end tempo, and/or set length of time for adjustment of the variable tempo of an audio file in the musical arrangement having the global tempo.
A computer implemented method allows a user to adjust a variable tempo of an audio file independent of a global tempo of a musical arrangement. The method can include causing the display of a musical arrangement having a global tempo. The musical arrangement can include an audio file having a variable tempo which is independent of the global tempo. The method can then include adjusting the variable tempo of the audio file so that the variable tempo begins at an initial tempo and adjusts to an end tempo over a set length of time. In some embodiments, either the initial tempo or end tempo is equal to the global tempo.
Many other aspects and examples will become apparent from the following disclosure.
In order to facilitate a fuller understanding of the exemplary embodiments, reference is now made to the appended drawings. These drawings should not be construed as limiting, but are intended to be exemplary only.
The functions described as being performed at various components can be performed at other components, and the various components can be combined and/or separated. Other modifications also can be made.
Thus, the following disclosure ultimately will describe systems, computer readable media, devices, and methods for adjusting a variable tempo of an audio file independent of a global tempo in a musical arrangement using a digital audio workstation. Many other examples and other characteristics will become apparent from the following description.
Referring to
The computer 102 can be a data processing system suitable for storing and/or executing program code, e.g., the software to operate the GUI which together can be referred to as a DAW. The computer 102 can include at least one processor, e.g., a first processor, coupled directly or indirectly to memory elements through a system bus. The memory elements can include local memory employed during actual execution of the program code, bulk storage, and cache memories that provide temporary storage of at least some program code in order to reduce the number of times code must be retrieved from bulk storage during execution. Input/output or I/O devices (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled to the system either directly or through intervening I/O controllers. Network adapters may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modem and Ethernet cards are just a few of the currently available types of network adapters. In one or more embodiments, the computer 102 can be a desktop computer or a laptop computer.
A MIDI controller is a device capable of generating and sending MIDI data. The MIDI controller can be coupled to and send MIDI data to the computer 102. The MIDI controller can also include various controls, such as slides and knobs that can be assigned to various functions within the DAW. For example, a knob may be assigned to control the pan on a first track. Also, a slider can be assigned to control the volume on a second track. Various functions within the DAW can be assigned to a MIDI controller in this manner. The MIDI controller can also include a sustain pedal and/or an expression pedal. These can affect how a MIDI instrument plays MIDI data. For example, holding down a sustain pedal while recording MIDI data can cause an elongation of the length of the sound played if a piano software instrument has been selected for that MIDI track.
As shown in
An instrument capable of generating electronic audio signals can be coupled to the computer 102. For example, as shown in
The external MIDI device 110 can be coupled to the computer 102. The external MIDI device 110 can include a processor, e.g., a second processor which is external to the processor 102. The external processor can receive MIDI data from an external MIDI track of a musical arrangement to generate corresponding sounds. A user can utilize such an external MIDI device 110 to expand the quality and/or quantity of available software instruments. For example, a user may configure the external MIDI device 110 to generate electric piano sounds in response to received MIDI data from a corresponding external MIDI track in a musical arrangement from the computer 102.
The computer 102 and/or the external MIDI device 110 can be coupled to one or more sound output devices (e.g., monitors or speakers). For example, as shown in
The one or more sound output devices can generate sounds corresponding to the one or more audio signals sent to them. The audio signals can be sent to the monitors 112, 114 which can require the use of an amplifier to adjust the audio signals to acceptable levels for sound generation by the monitors 112, 114. The amplifier in this example may be internal or external to the monitors 112, 114.
Although, in this example, a sound card is internal to the computer 102, many circumstances exist where a user can utilize an external sound card (not shown) for sending and receiving audio data to the computer 102. A user can use an external sound card in this manner to expand the number of available inputs and outputs. For example, if a user wishes to record a band live, an external sound card can provide eight (8) or more separate inputs, so that each instrument and vocal can each be recorded onto a separate track in real time. Also, disc jockeys (djs) may wish to utilize an external sound card for multiple outputs so that the dj can cross-fade to different outputs during a performance.
Referring to
As shown, the lead vocal track, 202, is an audio track. One or more audio files corresponding to a lead vocal part of the musical arrangement can be located on this track. In this example, a user has directly recorded audio into the DAW on the lead vocal track. The backing vocal track, 204, is also an audio track. The backing vocal track 204 can contain one or more audio files having backing vocals in this musical arrangement. The electric guitar track 206 can contain one or more electric guitar audio files. The bass guitar track 208 can contain one or more bass guitar audio files within the musical arrangement. The drum kit overhead track 210, snare track 212, and kick track 214 relate to a drum kit recording. An overhead microphone can record the cymbals, hit-hat, cow bell, and any other equipment of the drum kit on the drum kit overhead track. The snare track 212 can contain one or more audio files of recorded snare hits for the musical arrangement. Similarly, the kick track 214 can contain one or more audio files of recorded bass kick hits for the musical arrangement. The electric piano track 216 can contain one or more audio files of a recorded electric piano for the musical arrangement.
The vintage organ track 218 is a MIDI track. Those of ordinary skill in the art will appreciate that the contents of the files in the vintage organ track 218 can be shown differently because the track contains MIDI data and not audio data. In this example, the user has selected an internal software instrument, a vintage organ, to output sounds corresponding to the MIDI data contained within this track 218. A user can change the software instrument, for example to a trumpet, without changing any of the MIDI data in track 218. Upon playing the musical arrangement the trumpet sounds would now be played corresponding to the MIDI data of track 218. Also, a user can set up track 218 to send its MIDI data to an external MIDI instrument, as described above.
Each of the displayed audio and MIDI files in the musical arrangement as shown on screen 200 can be altered using the GUI. For example, a user can cut, copy, paste, or move an audio file or MIDI file on a track so that it plays at a different position in the musical arrangement. Additionally, a user can loop an audio file or MIDI file so that it is repeated, split an audio file or MIDI file at a given position, and/or individually time stretch an audio file for tempo, tempo and pitch, and/or tuning adjustments as described below.
Display window 224 contains information for the user about the displayed musical arrangement. As shown, the current tempo in bpm of the musical arrangement is set to 120 bpm. The position of playhead 220 is shown to be at the thirty-third (33rd) bar beat four (4) in the display window 224. Also, the position of the playhead 220 within the song is shown in minutes, seconds etc.
Tempo changes to a musical arrangement can affect MIDI tracks and audio tracks differently. In MIDI files, tempo and pitch can be adjusted independently of each other. For example, a MIDI track recorded at 100 bpm (beats per minute) can be adjusted to 120 bpm without affecting the pitch of the sound generators played by the MIDI data. This occurs because the same sound generators are being triggered by the MIDI data, they are just being triggered faster in time. In order to change the tempo of the MIDI file, the signal clock of the relevant MIDI data is changed. However, tempo changes to an audio file inherently adjust the pitch of the file as well. For example, if an audio file is sped up, the pitch of the sound goes up. Similarly, if an audio file is slowed, the pitch of the sound goes down.
In regards to digital audio files, one way that a DAW can change the duration of an audio file to match a new tempo is to resample it. This is a mathematical operation that effectively rebuilds a continuous waveform from its samples and then samples that waveform again at a different rate. When the new samples are played at the original sampling frequency, the audio clip sounds faster or slower. In this method, the frequencies in the sample are scaled at the same rate as the speed, transposing its perceived pitch up or down in the process. In other words, slowing down the recording lowers the pitch, speeding it up raises the pitch. Thus, using resampling, the pitch and tempo of an audio are linked.
A DAW can use a process known as time stretching to adjust the tempo of audio while maintaining the original pitch. This process requires analysis and processing of the original audio file. Those of ordinary skill in the art will recognize that various algorithms and methods for adjusting the tempo of audio files while maintaining a consistent pitch can be used.
One way that a DAW can stretch the length of an audio file without affecting the pitch is to utilize a phase vocoder. The first step in time-stretching an audio file using this method is to compute the instantaneous frequency/amplitude relationship of the audio file using the Short-Time Fourier Transform (STFT), which is the discrete Fourier transform of a short, overlapping and smoothly windowed block of samples. The next step is to apply some processing to the Fourier transform magnitudes and phases (like resampling the FFT blocks). The third step is to perform an inverse STFT by taking the inverse Fourier transform on each chunk and adding the resulting waveform chunks.
The phase vocoder technique can also be used to perform pitch shifting, chorusing, timbre manipulation, harmonizing, and other modifications, all of which can be changed as a function of time.
Another method that can be used for time shifting audio regions is known as time domain harmonic scaling. This method operates by attempting to find the period (or equivalently the fundamental frequency) of a given section of the audio file using a pitch detection algorithm (commonly the peak of the audio file's autocorrelation, or sometimes cepstral processing), and cross-fade one period into another.
The DAW can combine the two techniques (for example by separating the signal into sinusoid and transient waveforms), or use other techniques based on the wavelet transform, or artificial neural network processing, for example, for time stretching. Those of ordinary skill in the art will recognize that various algorithms and combinations thereof for time stretching audio files based on the content of the audio files and desired output can be used by the DAW.
As shown in
A user can set the initial tempo, end tempo, and/or set length of time by use of an input device such as a mouse. A user can select a fade tool function, e.g. selecting the function from a menu with a mouse. Then the user can drag a rubber band box, using the fade tool, over a selected area of an audio file to set the initial tempo, end tempo, and/or set length of time. Additionally, a user can modify the curve of a fade by grabbing and moving a displayed tempo adjustment line. The DAW can adjust the curve of the tempo adjustment line by curve fitting based on a selected position by a user. For example, using a mouse, a user can drag and adjust the tempo adjustment line and the DAW displays the resulting curved tempo adjustment line based on a position of the initial tempo, position of the end tempo, and position of the mouse cursor.
For example, a user can drag a box, e.g. a rubber band box, over the beginning of the first audio file to a desired variable tempo fade-in position on the first audio file. Upon creating this box, the DAW can set the initial tempo, end tempo, and/or set length of time. Additionally, a user can then further fine tune the initial tempo, end tempo, and/or set length of time. For example a user can manually enter values for a set length of time and a curvature desired for a given audio file as shown in box 332. Furthermore, a user can then adjust the tempo fade-in curve of the first audio file to be a constant rate, exponential increasing rate, or exponential decreasing rate, for example. The DAW can allow other adjustment rates and combinations thereof. In
Upon receiving a command to play the musical arrangement, the DAW can play all files in the arrangement according to the global tempo, except the audio files that have variable tempo adjustment fades. For example, the first audio file 308 includes an exponential decreasing tempo fade-in as shown. The DAW can use a resampling algorithm, as described above, to alter the variable tempo of the first audio file. In this example, the pitch of the first audio file will start at a low value corresponding to the initial tempo and the pitch will increase until the end tempo is reached. In this example, upon reaching the end tempo, the first audio file will play at its original pitch. This can cause the DAW to play the first audio file similar to a classic tape varispeed speed-in effect. The DAW can utilize other tempo-adjusting algorithms as well.
Furthermore, as shown in
Upon receiving a command to play the musical arrangement, the DAW can play the arrangement according to the global tempo, but output the second audio file according to the variable tempo corresponding to the linear tempo fade-out as shown. The DAW can use a resampling algorithm, as described above, to alter the variable tempo of the second audio file. In this example, the pitch of the second audio file will start at an original pitch corresponding to the initial tempo and the pitch will decrease until the end tempo is reached. In this example, as approaching the end tempo, the second audio file can go down in pitch. This can cause the DAW to play the second audio file similar to a classic tape varispeed speed-down effect.
Furthermore, as shown in
The cross-fade of variable tempo between the third audio 320 and fourth audio file 326 file has a set time length of 1 bar (4 beats), beginning at a second beat of bar 12 and ending at a second beat of bar 13. A user can modify the tempo cross-fade adjustment between the third audio file 320 and the fourth audio file 326 to be linear, exponential increasing, or exponential decreasing, for example. The DAW can implement other patterns for adjustment for such a cross-fade tempo adjustment.
Upon receiving a command to play the musical arrangement, the DAW can play the arrangement according to the global tempo, but output the third and fourth audio file according to the variable tempo corresponding to the linear tempo cross-fade as shown for the third and fourth audio file. The DAW can use a resampling algorithm, as described above, to alter the variable tempo of the third and fourth audio file. In this example, the pitch of the third audio file will start at an original pitch corresponding to the initial tempo and the pitch will decrease until the end tempo is reached. Furthermore, in the example, the pitch of the fourth audio file will start at a low value and increase to an original pitch when the end tempo for the fourth audio file is reached. This can cause the DAW to play the third and fourth audio files with a classic tape varispeed cross-fade speed-down/speed-up effect. The DAW can perform variable tempo adjustments with any known method for adjusting tempo of an audio file.
Referring to
At block 402, a musical arrangement with a global tempo and one or more audio files with a variable independent tempo is displayed. For example, the computer 102, e.g., processor, causes the display of the musical arrangement with a global tempo and the audio file with a variable independent tempo. In another example, a display module residing on a computer-readable medium can display the musical arrangement with a global tempo and the audio file with a variable independent tempo. After displaying the musical arrangement, the method 400 can proceed to block 404.
At block 404, the variable tempo of an audio file can be adjusted. The variable tempo of the audio file can include an initial tempo, an end tempo, and a set length of time for adjustment. For example, dragging a graphical box over an audio file including a variable tempo can allow a user to enter a desired initial tempo, end tempo, and/or set length of time for adjusting the tempo of the audio file, independent of the global tempo of the arrangement. In one example, the initial tempo and end tempo are pre-defined. For example an initial tempo can be pre-defined as 0 bpm and the end tempo can be pre-defined as equal to the global tempo for a tempo fade-in. For a tempo fade-out, the initial tempo can be pre-defined as equal to the global tempo and the end tempo can be pre-defined as 0 bpm. Dragging a graphical box over an intersection of two audio files can allow a user to enter a tempo cross-fade, i.e. initial tempo, end tempo, and/or set length of time for fading out one of the audio files and allow a user to enter a different initial tempo, end tempo and/or set length of time for the other audio file. These adjustments overlapping create a tempo cross-fade as described above.
A tempo adjustment can be at an exponentially decreasing rate, exponentially increasing rate, or a constant (linear) rate. The DAW can implement other rates for variable tempo adjustment of an audio file.
The processor or a processor module can display a GUI to illustrate tempo adjustments that will be applied to audio files in a musical arrangement upon receiving a play command, as shown in
At block 406, upon receiving a play command, the method can include outputting the musical arrangement according to a global tempo and outputting each audio file including a variable tempo that is independent of the global tempo. For example, the DAW can output each audio file including a variable tempo by utilizing a resampling algorithm creating classic tape varispeed effects. In such an implementation, the pitch and tempo of each audio file including a variable tempo adjustment would be linked. The DAW can utilize other algorithms for audio tempo adjustment.
The technology can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment containing both hardware and software elements. In one embodiment, the invention is implemented in software, which includes but is not limited to firmware, resident software, microcode, etc. Furthermore, the invention can take the form of a computer program product accessible from a computer-usable or computer-readable medium providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer-usable or computer readable medium can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium (though propagation mediums in and of themselves as signal carriers are not included in the definition of physical computer-readable medium). Examples of a physical computer-readable medium include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) and DVD. Both processors and program code for implementing each as aspect of the technology can be centralized and/or distributed as known to those skilled in the art.
The above disclosure provides examples and aspects relating to various embodiments within the scope of claims, appended hereto or later added in accordance with applicable law. However, these examples are not limiting as to how any disclosed aspect may be implemented, as those of ordinary skill can apply these disclosures to particular situations in a variety of ways.
