Real time audio mixer

• US 5,734,731 A
• Filed: 11/29/1994
• Issued: 03/31/1998
• Est. Priority Date: 11/29/1994
• Status: Expired due to Fees

• Current Assignee: Elliot S. Marx
• Original Assignee: Elliot S. Marx
• Inventors: Marx, Elliot S.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Mei, Xu
• Application Number:
  US08/346,390
• Time in Patent Office: 1,218 Days
• Field of Search: 381/119, 381/55, 381/59, 381/58
• US Class Current: 381/119
• CPC Class Codes: H04H 60/04 Studio equipment; Interconnection of studios

Abstract

An audio mixer for use with audio input devices for buffering audio input signals in a dual buffering system where the dual buffering system includes a mass storage device and a dynamic storage device. The dual buffering system enables large quantities of audio data to be stored allowing audio effects and mixing capabilities including simulation of vinyl record scratching, inter alai. The audio mixer also automatically determine beats thus allowing beat skipping, automatic correction for audio input defects as well as synchronization of two or more audio inputs, inter alia.

Claims

1. An audio mixing system in electrical communication with an audio input device which generates audio data having a pitch, and in electrical communication with an audio output device, said audio mixing system comprising:

audio input means adapted to receive said audio data from the audio input device;

buffer means in electrical communication with said audio input means for storing said audio data;

processing means selectable between an inactive and an active mode, the inactive mode for accumulating the audio data within the buffer means, the active means for withdrawing said audio data stored by the buffer means and processing the audio data while continuing to receive the audio data within the buffer means;

pitch means disposed in the processing means for maintaining the pitch of the audio data at a substantially constant level when a speed of output of the audio data to the audio output device is accelerating or decelerating and for determining a segmentation interval representative of a portion of the audio data over a time period and determining a modification factor that is the time period multiplied by a predetermined percentage of the speed of output and selectively altering the audio data by a portion of the segmentation interval by selectively modifying the audio data in the time period by the modification factor such that the audio data so modified maintains the pitch of the audio data not so modified and transmitted while the speed of output of the audio data so modified to the audio output device is accelerated or decelerated; and

audio output means in electrical communication with said processing means adapted to transmit said processed audio data to said audio output device.

2. The audio mixing system according to claim 1 wherein said buffering means comprises

mass storage means for statically storing large quantities of said audio data and, in the active mode, for transmitting the audio data upon receiving a request signal by said processing means;

and

memory means for providing dynamic storage of the audio data transmitted by said mass storage means such that the audio data is addressable by said processing means.

3. The audio mixing system according to claim 2 wherein said memory means is continuously refreshed from said mass storage means in such a way that the memory means always contains a first block of audio data that has already been sent to the audio output means and a second block of data that has not yet been sent to the audio output means.

4. The audio mixing system according to claim 3 wherein said first block of audio data is sufficient to produce at least one half second of audio output to said audio output means.

5. The audio mixing system according to claim 1 further comprising a turntable which is a drive to rotate at a substantially constant rotational velocity, said turntable in electrical communication with said processing means such that changes in said rotational velocity are transmitted to said processing means such that the processing means adjusts the audio data received from the audio input device to flow according to the changes in rotational velocity of the turntable.

6. The audio mixing system according to claim 5 wherein said turntable is adapted to be manually rotated in a backward and forward motion which causes the processing means to transmit processed data simulating a scratching of a vinyl record.

7. The audio mixing system according to claim 1 wherein said processing means further comprise down beat means for tracking down beats by determining a period of peak amplitudes within the audio data and for utilizing the down beats to avoid imperfections in the audio data by skipping to a next consecutive down beat.

8. The audio mixing system according to claim 1 wherein the pitch is maintained by repeating the portion of the segmentation interval during acceleration of the output of the audio data and subtracting the portion of the segmentation interval during deceleration of the output of the audio data.

9. The audio mixing system according to claim 8 wherein the portion of the segmentation interval is taken from a tail section of the segmentation interval consisting of oscillations having small amplitudes relative to a beat.

10. The audio mixing system according to claim 9 wherein said portion of the segmentation interval is added with a low frequency distortion to substantially eliminate a discontinuity between an end of a segment defined by the segmentation interval and said portion of the segmentation interval being appended.

11. The audio mixing system according to claim 10 wherein said low frequency distortion is a saw-tooth waveform which pulls the end of said segment up and pulls a beginning of the portion being appended down to form a continuous audio signal.

12. The audio mixing system according to claim 8 wherein said processing means is adapted to automatically synchronize two or more audio input signals by adjusting segmentation intervals.

13. A music mixer for determining a beat of a song from a music input device said sound mixer comprising:

an audio input adapted to receive a music signal representative of the song from the music input device;

processing means in electrical communication with the audio input for analyzing said audio data to determine a tempo by locating peak relative amplitudes of the audio data and comparing the peak relative amplitudes to a predetermined note structure to determine a best fit between the relative peak amplitudes and the predetermined note structure, the predetermined note structure having a reference number of beats per minute and at least one tempo representative of the reference number of beats per minute; and

beat means disposed in the processing means for comparing note intervals, which are compatible with the at least one tempo, to the relative peak amplitudes and generating beats representative of a one of the note intervals, where the beats of the one of the note intervals substantially coincides with the relative peak amplitudes of the audio data.

14. The music mixer system according to claim 13 further comprising:

user interface means in electrical communication with said processing means for displaying information relating to the beat of a song; and

an output port disposed upon the interface means adapted to output a driving signal from the user interface means where the driving signal is selectable to indicate beat information and said driving signal is usable by a peripheral to indicate said beat information.

15. The music mixer system according to claim 13 further comprising memory means in electrical communication with said processing means for dynamically storing said beat information therein.

16. A method for mixing a first audio signal from an audio input device and a first processing signal from a turntable device to produce an audio output signal, said method comprising:

receiving first audio signal from the audio input device;

storing said first audio signal;

determining beats by comparing relative amplitude peaks in first audio signal to predetermined note structures having predetermined beats and generating beats of the audio signal that correspond to the predetermined beats of one of the predetermined note structures;

receiving first processing signal having a user selected number of beats per minute from the turntable device generated by actuating the turntable device, where the user selected number of beats per minute is representative of a change in a tempo of the audio signal; and

selectively processing the first audio signal such that the first audio signal is drawn from storage and is programmably altered in accordance with the first processing signal to generate the audio output signal.

17. A method according to claim 16 further comprising a step of determining a down beat as a strongest relative beat a measure and a subsequent beat as a quarter beat.

18. A method according to claim 16 further comprising a step of synchronizing the first audio signal to a second audio signal by altering a segmentation interval of the second audio signal.