System for managing distribution of digital audio content

#This invention relates to a system for managing distribution of digital audio content and, particularly, to a system which enables highly effective compression of digital audio files as well as digital rights and content management functions in the handling of such files.

#Digital audio content has improved significantly since the 1980s when 16-bit encoding and 44.1 Khz sampling was adopted as a new standard. Digital audio encoded in 16-bit bytes could represent a better dynamic range than previous recordings on vinyl records, and the 44.1 Khz sampling rate complied with the Nyquist rule that it should be twice the highest frequency the human ear can discern. However, current digital audio standards have increased the dynamic range for digital encoding to 24 bits and the sampling rate to 96 Khz for DVD audio content and as high as 192 Khz for “professional” applications. The amount of recorded data has grown from 45 MB for 4 minutes of stereo at 16-bits, 44.1 Khz recording, to 270 MB for that same 4 minutes at 24-bits, 192 Khz. The volume of data for digital audio files has thus increased more than 3× to 6× to obtain a higher resolution and quality of recorded sound.

#At the same time, music lovers have found new channels on the Internet for accessing music. Hearing new music is of most interest when it can be sampled before purchase, and freely shared among friends with the same musical interests. The Internet has allowed users to readily share songs and even whole CDs with others by posting them on peer-to-peer networks. Concurrently, new compression methodologies have been developed to allow large digital audio files to be compressed into smaller files sizes for delivery across the Internet to a broad audience of users who have more limited bandwidth access. For example, MP3 encoding was developed as an offshoot of MPEG standards developed by the Motion Pictures Experts Group. The MP3 format has been widely used to share music files on peer-to-peer networks across the Internet. However, the ease with which music files can now be shared and transmitted ubiquitously on the Internet has led to widespread copyright piracy of illegally copied music, causing the recording industry billions of dollars in lost revenues. Widespread copyright piracy has also undermined economic incentives for recording artists to create new music and make it available in public distribution systems where it can be illegally copied.

#FIG. 1 is a schematic block diagram illustrating an example of the logic sequence for a system for managing distribution of digital audio content in accordance with the present invention.

#FIG. 2 is a schematic block diagram of an apparatus for encoding an audio waveform as time-demarcated digital messages of a digital audio content file.

#FIG. 3 is a schematic block diagram of an apparatus for reproducing (playing back) an original audio waveform from the encoded digital audio content file.

#Referring now to the drawings and in particular to FIG. 1 thereof, the system for managing distribution of digital audio content in accordance with the present invention is illustrated schematically. In this system, digital audio content is digitally encoded using a “vector” encoding method, for example, as described in U.S. Pat. No. 6,020,840 and 6,177,898, incorporated herein by reference (explained in greater detail below). The preferred vector-encoding method described in these patents is referred to herein as “WaveTrace” technology. However, it is to be understood that other equivalent vector-encoding methods may also be used. In vector-encoding, the digital audio content is represented as a series of digital messages specifying a multiplier number of amplitude increments of common slope traversed in a segment of the audio waveform, the elapsed time of traverse, and its polarity (up/down). The vector-encoding allows the higher frequency segments of the audio file to be identified with a tracer bit that is set to logical “1” or “high” or other message segment as appropriate. These are identified as segments having an amplitude-per-time traversal rate that exceeds a predetermined level. Other digital messages can be embedded into the data stream, such as the manufacturer's ID (or authorized host-ID), subscriber, copyright, or encryption key information in the data stream. They are tagged as management data, rather than audio data, so that they do not form a part of the playback stream.

#The vector-encoded digital audio content may be distributed as a hardcopy on a CD purchased by a legitimate user, as indicated at Block 110, which is free to be played back in full resolution an unlimited number of times on any compatible (vector-decoding-enabled) player having firmware enabling playback of the vector-encoded audio file, indicated at Block 111. A distributor ID code may be used initially in place of a host-ID code, and is recognized by the player as permitting full playback of the audio file from the CD. However, when the vector-encoded audio file is copied (“ripped”) from the CD, at Block 112, or downloaded from the Internet, at Block 113, to a host environment, such as a personal computer (PC) indicated at Block 114, a vector-decoding enabled (WaveTrace) software player installed on the PC will execute a prescribed sequence of distribution management functions in accordance with the present invention. When the receiving host environment attempts playback, at Block 115, the WaveTrace player checks the distribution rights messages embedded in the audio file before playback, at Block 116. If the audio file has been loaded from a legitimately purchased CD, the WaveTrace player checks for the distributor's ID code, at Block 117. If the distributor's ID code is recognized, the WaveTrace player changes it to a host-ID code identifying the user as the authorized host environment, at Block 118. The host-ID code may be generated from the user's machine serial number or the serial numbers of components in the host machine such as the microprocessor, hard drive, or operating system license number. Alternatively, or as a follow up, the user may be prompted to register its host-ID code for the audio file with an Online Registration Site established to manage the distribution rights for audio files within the system, indicated at Block 119. Completion of the registration step allows the now-authorized user to proceed with playback at full resolution and an unlimited number of times, at Block 120. Unlimited playback is enabled when the WaveTrace player checks the audio file for the host-ID code and finds one that matches the code numbers for that user or user's machine.

#If the WaveTrace player does not find a distributor's ID code at Block 117, it checks for a matching host-ID code at Block 121. If a host-ID code match is found, the WaveTrace player proceeds to unlimited playback at Block 120. If a host-ID code match is not found, the WaveTrace player enables only limited playback at low resolution, by flat-lining the marked higher-frequency digital messages (as described further below), and for a limited number of times “x”, indicated at Block 122. A count of playback times is updated in the management data of the audio file. If the count is below “x”, low resolution playback is enabled. When the count reaches “x”, playback is no longer enabled and instead the user is prompted to pay a license fee for full playback rights, at Block 123. The user can then go to the Online Registration Site, at Block 124, and arrange for payment of the required license fee and also receive a decryption/encryption key used by the WaveTrace system to rewrite the host-ID code embedded in the audio file to that of the registering user or user's machine. If the user does not complete the license payment and registration procedure, the WaveTrace player exits the management sequence without enabling any level of playback, at Block 125.