U.S. patent application number 09/805170 was filed with the patent office on 2001-11-15 for automatic compilation of songs.
Invention is credited to Cliff, David Trevor.
Application Number | 20010039872 09/805170 |
Document ID | / |
Family ID | 8172979 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010039872 |
Kind Code |
A1 |
Cliff, David Trevor |
November 15, 2001 |
Automatic compilation of songs
Abstract
A method of automatically producing a compilation mix from a set
of songs is disclosed. The method comprises the steps of generating
(22) a beat profile comprising a temporal map representing an ideal
rate of repeat of the dominant beat for the compilation mix at
different points in time over the duration of the compilation,
generating (21) at least one set of song data indicative of the
rate of repeat of the dominant beat for each of the songs in the
set of songs, and allocating (24) the songs temporally within the
compilation mix by processing the song data together with the
temporal map, the songs being located temporally with respect to
one another such that the rate of repeat of the dominant beat of
the compilation approximates that indicated by the temporal map and
end portions of adjacent songs overlap.
Inventors: |
Cliff, David Trevor;
(Southville, GB) |
Correspondence
Address: |
John W. Ryan
c/o Wilmer, Cutler & Pickering
2445 M Street NW
Washington
DC
20037-1420
US
|
Family ID: |
8172979 |
Appl. No.: |
09/805170 |
Filed: |
March 14, 2001 |
Current U.S.
Class: |
84/609 ;
G9B/27.012 |
Current CPC
Class: |
G10H 2250/035 20130101;
G10H 1/0033 20130101; G11B 27/034 20130101; G10H 1/40 20130101;
G11B 2220/2545 20130101; G11B 2220/218 20130101; G11B 20/00007
20130101 |
Class at
Publication: |
84/609 |
International
Class: |
G10H 001/26 |
Foreign Application Data
Date |
Code |
Application Number |
May 11, 2000 |
EP |
00303960.9 |
Claims
1. A method of automatically producing a compilation mix from a set
of songs comprising the steps of (a) generating a beat profile
comprising a temporal map representing an ideal rate of repeat of
the dominant beat for the compilation mix at different points in
time over the duration of the compilation; (b) generating at least
one set of song data indicative of the rate of repeat of the
dominant beat for each of the songs in the set of songs, (c)
allocating the songs temporally within the compilation mix by
processing the song data together with the temporal map, the songs
being located temporally with respect to one another such that the
rate of repeat of the dominant beat of the compilation approximates
that indicated by the temporal map and end portions of adjacent
songs overlap.
2. A method according to claim 1 which further includes a step of
selecting the set of songs to form the compilation mix from one or
more master sets of songs.
3. A method according to claim 1 or claim 2 in which step (a)
includes the sub-step of selecting a beat profile from a set of
different predetermined beat profiles.
4. A method according to any preceding claim in which step (b)
comprises processing each song that is selected to produce a beat
value representative of the rate of repetition of the dominant beat
of the song.
5. A method according to any preceding claim which further includes
the step of processing each song to produce a time value indicative
of the overall duration of the song from start to finish.
6. A method according to any preceding claim which additionally or
alternatively includes the step of identifying the location of any
beat dropouts within each song.
7. A method according to any preceding claim in which the beat
profile is processed to calculate the value and the temporal
position of the minima and maxima beat rate in the profile, the
songs being allocated to their temporal positions within the
compilation such that the songs having the minima and maxima beat
per minute are located at the point in the sequence corresponding
approximately to the position of the minima and maxima of the
temporal map.
8. A method according to claim 7 in which the remaining songs are
allocated to the compilation mix to complete the sequence by
matching the beat rate of the songs to the temporal profile using a
"best-fit" approximation.
9. A method according to any preceding claim in which, subsequent
to allocating the songs to the temporal map to determine the order
of the songs, the songs are located relative to one another in time
such that the songs overlap in a predetermined manner.
10. A method according to claim 9 in which the predetermined amount
of overlap between songs is chosen to be the same for each
song.
11. A method according to claim 9 or claim 10 in which where the
song data indicates that a beat drop out is present in a song, the
drop-out is used as the point at which the song ends and the
subsequent song begins.
12. A method according to any preceding claim in which the songs
are located temporally so that the dominant beats occurring in the
overlap section from each song are aligned temporally.
13. A method according to claim 12 in which one or both of a pair
of overlapping portions are processed to match their rate of beat
repetition by speeding up one song with time-compression in the
overlap region, or slowing down one song with time-stretching, or a
combination of both.
14. A method according to claim 13 which further comprise the step
of gradually returning the speed of the remainder of the song over
time to bring it back to its nominal (pre-adjusted) beat repetition
rate.
15. A method according to any preceding claim which further
includes the step of fading out the amplitude (volume) of the
overlapping end portion of a song and/or fading in the overlapping
start portion of a song.
16. Apparatus adapted to automatically produce a compilation mix of
songs in accordance with any one of claims 1 to 15.
17. Apparatus according to claim 16 which includes a first area of
memory in which the songs to be compiled are stored, a processing
unit which processes the data in the memory, and a computer program
which, when run on the processor instructs the processor to perform
the method of any one of claims 1 to 15.
18. Apparatus according to claim 17 in which a second area of
memory is provided in which one or more user defined beat profiles
are stored for access by the processor.
19. Apparatus according to any one of claims 16 or 18 which further
includes a connector for connection to an output storage device
adapted to record the resulting compilation on a storage data
carrier.
20. Apparatus according to any one of claims 16 to 19 which further
includes a data input device whereby a user may select the temporal
profile in response to a prompt by the apparatus.
21. A data carrier including a computer program which, when
operating on a computer, produces an apparatus according to any one
of claims to 16 to 20.
Description
[0001] This invention relates to a method and an apparatus for
producing a compilation of overlapping songs, each song in the
compilation having a sequence of repeating beats. The compilation
may, for instance, be suitable for recording onto a data carrier
such as a compact disc, or for broadcast by a radio station.
[0002] It will be understood that by song we mean any musical song
or tune, with or without a vocal element, and with or without
elements of melody and harmony, where the rhythmic element of the
music is characterised by repetitive beats. The invention is
especially but not exclusively suitable for compilations of dance
music, which is generally characterised by a continuous repetitive
sequence of beats. The beat is important for dance music and
usually dominates the overall subjective impression provided by the
song.
[0003] It is well known to manually produce a compilation by
"mixing" together a set of individual songs, usually dance music
songs, to form a single continuous track in which one song is
merged seamlessly into the adjacent song or songs. The resulting
compilation comprises an apparently continuous stream of music.
[0004] At present, the production of such "compilations" (sometimes
referred to as "mixes") have required many hours work by skilled
Disk Jockeys (DJ's). The job of a DJ involves great skill in
deciding on the order of the songs, (the "sequence") and also skill
in seamlessly mixing one track into the other. The amount of time
and skill needed puts the production of compilation mixes beyond
the abilities of most listeners.
[0005] We are aware of European patent application No. EP
0932157A1. This document describes an apparatus and method for
automatically performing a cross-over between two songs which are
played back consecutively. As soon as the start of a pre-determined
end part of the first song is detected, this end part is played
simultaneously with a pre-determined beginning part of the second
song. After play-back of the end part concludes, the play-back
continues for the second song only. During simultaneous play-back a
fade-out and/or a fade-in may be performed for the end part and/or
the begin part respectively.
[0006] The apparatus known from EP 0932157 has problems in that it
requires, as a pre-requisite, that two songs are provided which
include markers for the end part and begin part. Most, if not all
songs, can not be purchased with suitable markers allocated to them
for use by such an apparatus. It is not taught how such markers are
established, and presumably a skilled operator is needed in order
to set the markers prior to play back and choose the sequence of
the songs.
[0007] An object of the present invention is to produce a method
and apparatus for the production of a compilation mix of songs
which does not require the presence of pre-established markers and
provides for greater flexibility.
[0008] According to the present invention, a method of
automatically producing a compilation mix from a set of songs is
provided, the method comprising the steps of:
[0009] (a) generating a beat profile comprising a temporal map
representing an ideal rate of repeat of the dominant beat for the
compilation mix at different points in time over the duration of
the compilation;
[0010] (b) generating at least one set of song data indicative of
the rate of repeat of the dominant beat for each of the songs in
the set of songs,
[0011] (c) allocating the songs temporally within the compilation
mix by processing the song data together with the temporal map, the
songs being located temporally with respect to one another such
that the rate of repeat of the dominant beat of the compilation
approximates that of the temporal map and end portions of adjacent
songs overlap. The invention thus provides a method of
automatically determining the sequence of the songs according to
their rate of repeat of the dominant beat (the tempo--usually
measured as beats per minute) and an ideal temporal map for the
resulting compilation. This enables the production of effective
compilations with a predetermined overall feel to be achieved from
any set of songs.
[0012] The invention may include a preliminary step of selecting
the set of songs to form the compilation mix from one or more
master sets of songs.
[0013] The method step (a) may comprise the sub-steps of selecting
a beat profile from a set of different predetermined beat profiles.
The predetermined beat profiles may be stored within an area of
memory.
[0014] The beat profile may comprise a quantitative map of the
ideal beat repetition rate throughout the duration of the
compilation to be constructed. It may comprise a set of beat rate
values and corresponding time values for a compilation.
[0015] Alternatively, the temporal beat profile may be a
qualitative map in which relative values of the beat repetition
rate at various time locations in the compilation are provided. For
instance, the map may consist of the location in time in the
compilation of where the maximum and minimum rates should be, and
the change in rate between these points.
[0016] The time information in the map may also be either
quantitative, i.e. from zero to 74 minutes or qualitative, i.e.
from "start" to "finish". The beat profile may be stored as a set
of pairs of data, each pair consisting of a time location in the
compilation and either a quantitative or qualitative value of the
beat repetition rate.
[0017] The predetermined beat profiles may all be of a
predetermined duration. In that case, the method may further
comprise the steps of temporally expanding or compressing the
selected profile to match the length of the compilation mix that is
being produced.
[0018] The step of selecting the beat profile may be automatically
performed by the method. A beat profile may, for example, be
selected at random from a set of profiles.
[0019] Alternatively, the beat profile may be entered or selected
manually by a user. The method may therefore include a sub-step of
requesting a user to enter or to select a beat profile.
[0020] The step (b) of generating song data may comprise processing
each song that is selected to produce a beat value representative
of the rate of repetition of the dominant beat of the song.
[0021] Typically, the beat repetition rate (tempo) of a song will
remain substantially constant over the duration of the song. The
beat repetition data for each song may therefore comprise a step
of, for each song, measuring the beats per minute of only one part
of the song. This may, for instance, be a start portion, a middle
portion or an end portion of the song.
[0022] It may also include the step of processing each song to
produce a time value indicative of the overall duration of the song
from start to finish.
[0023] It may additionally or alternatively include the step of
identifying the location of any beat drop-outs within each song.
These represent points in the song where the beat stops before
restarting. For instance, in a dance music song it may be a point
at which a drum beat defining the dominant beat stops for a few
beats or measures before restarting.
[0024] The generated song data may be stored in individual data
files corresponding to each song or in a single file.
[0025] The beat profile may be used to calculate the value and the
temporal position of the minima and maxima beat rates in the
profile. Data indicative of the value and position may be stored in
a memory. In some arrangements, the temporal map may already be
stored in terms of minima and maxima, and so this processing is not
required.
[0026] The songs may be allocated to their temporal positions
within the compilation such that the songs having the minima and
maxima beat per minute are located at the point in the sequence
corresponding approximately to the position of the minima and
maxima of the temporal map.
[0027] The remaining songs may be allocated to the remaining
positions in the compilation mix to complete the sequence by
matching the beat rates of the songs to the temporal profile using
a "best-fit" approximation.
[0028] The allocation may be made by processing the song data in
combination with the temporal map.
[0029] It is expected that in many applications of the present
invention the duration of the created compilation will be required
to be no greater than some maximum time-duration M seconds. For
example, in creating a compilation to be written to a standard
length compact disc (CD), the CD format imposes a maximum duration
of 74 minutes (M=4440 seconds). In a broadcast application the
compilation mix may have to fit into a precise time slot (i.e.12:05
to 1:00am) and so the maximum time in this case would be 55
minutes. To create a continuous/seamless mix, the songs in the
compilation need to be overlapped so that the mix can cross-fade
from one song to another. A variety of overlaps are envisaged
within the scope of the present invention.
[0030] The method may therefore comprise the further step of, after
allocating the songs to the temporal map to determine the order of
the songs, locating the songs relative to one another in time such
that the songs overlap in a predetermined manner.
[0031] The predetermined amount of overlap between songs may
initially be chosen to be the same for each song.
[0032] For a set of N songs, with total combined length T seconds,
the initial amount of overlap L between each song may be
automatically determined from the relative values of M and T. If T
is greater than M, there is more music than can be fitted into the
time duration so each song may be overlapped by an equal amount
determined by the equation:
L=(T-M)/(N-1).
[0033] Subsequent to the generation of the initial overlap, the
individual overlap between pairs of songs may be adjusted. For
example, where the song data indicates that a beat drop out is
present in a song, this may be used as the point at which the song
ends and the subsequent song begins. In that case, the decision to
provide equal overlap may be overruled.
[0034] After initial overlap of the songs, the method may further
comprise the step of processing the songs so that the beats
occurring in the overlap section from each song are aligned
temporally.
[0035] This step may comprise the step of phase aligning the
overlapping songs so that the dominant beats of each song are
exactly aligned. Thus, the beats of each song will occur at the
same time and to the listener will appear as a single beat.
[0036] The dominant beats in the overlap can only be aligned
throughout the entire overlap portion if they are at the same
repetition rate.
[0037] The method may therefore include the step of time-stretch
and/or time-compression processing one or both of the overlapping
portions to match the rate of repetition. This may be achieved by
speeding up one song in the overlap region, or slowing down one
song, or a combination of both.
[0038] Where the method comprises the step of speeding up/slowing
down an overlapping portion of a song, the method may further
comprise the step of gradually adjusting the speed of the remainder
of the song over time to bring it back to its nominal
(pre-adjusted) beat repetition rate. The human ear is not
especially good at identifying slow changes in tempo over time, and
so such adjustment can be made without the user noticing in the
final compilation.
[0039] After the songs have been aligned the subsequent alterations
to the overlaps may require that the overall length of the
resulting compilation exceeds the allocated duration, i.e. exceeds
M seconds. In such a case, the method may further comprise the step
of automatically truncating the compilation by fading out the final
song early (before its end) or fading in the first song late (
after its start), or by a combination of both.
[0040] The same step of early/late fade can also be applied if the
duration of any one of the calculated overlaps exceeds a
predetermined value L. This can arise if the overlap is aligned
using a drop-out that occurs some way into a song. The value of L
may be quantitative, i.e. 30 seconds, or qualitative, i.e. 30
percent of the duration of a song. Thus, if the overlap exceeds the
predetermined threshold an appropriate fade-out, fade-in or both
may be used to lower the overlap to within the threshold. If no
maximum time limit is set, the overlap may be chosen at random or
set to some predetermined initial value, say 20 seconds. This may
also be used where the total length T of the songs for the
compilation are less than the predetermined limit M. The value of
the overlap may be selected as a function of the length of the
songs being compiled, for example as a percentage of the length of
an outgoing song, as a percentage of a length of an incoming song,
or as a percentage of the average length of the songs being
overlapped. This percentage could be fixed or generated at random
from a probability distribution.
[0041] The method may further include the step of fading out the
amplitude (volume) of the overlapping end portion of a song. The
method may also include the step of fading in the overlapping start
portion of a song. A linear increase in amplitude may be provided
or it may be faded in accordance with any other predetermined
pattern.
[0042] The method may further comprise the step of recording the
songs in their selected order over time onto a data carrier, such
as a compact disc.
[0043] According to a second aspect, the invention also provides
apparatus adapted to automatically produce a compilation mix of
songs in accordance with the method of the first aspect.
[0044] The apparatus may include a first area of memory in which
the songs to be compiled are stored, a processing unit which
processes the data in the memory, a computer program which, when
run on the processor instructs the processor to perform the method
of the first aspect of the invention.
[0045] A second area of memory may be provided in which one or more
user defined beat profiles are stored for access by the
processor.
[0046] The apparatus may further include a connector for connection
to an output storage device adapted to record the resulting
compilation on a storage data carrier. The storage device may
comprise a compact disc writer.
[0047] The apparatus may include a data input device whereby a user
may select the temporal profile in response to a prompt by the
apparatus. The apparatus may produce an audio or visual prompt.
[0048] According to a third aspect, the invention provides a data
carrier including a computer program which, when operating on a
computer, produces an apparatus according to the second aspect of
the invention.
[0049] There will now be described, by way of example only, one
embodiment of the present invention with reference to the
accompanying drawings, of which:
[0050] FIG. 1 is a schematic of an apparatus in accordance with the
present invention for automatically producing a compilation of
songs;
[0051] FIG. 2 is a general flow diagram of the overall method
carried out by the apparatus of FIG. 1;
[0052] FIG. 3 is a flow diagram illustrating the steps involved in
selecting the songs to be used in constructing the compilation
mix;
[0053] FIG. 4 is a flow diagram illustrating the steps of
calculating the temporal profile of the compilation mix;
[0054] FIG. 5 is a flow diagram illustrating the steps of
calculating the song data for storage in data files;
[0055] FIG. 6 is a flow diagram illustrating the steps of
allocating the songs to temporal locations within the
compilation;
[0056] FIG. 7 is a flow diagram of the steps for providing seamless
transitions between songs; and
[0057] FIG. 8 is a diagram showing three typical beat profiles.
[0058] FIG. 1 is a schematic diagram of an apparatus in accordance
with one aspect of the present invention.
[0059] The apparatus comprises three main functional elements.
Firstly, a memory storage area 1 is provided which stores, in
either digital or analogue form, a number of songs from which a
compilation mix is to be made. As shown, this comprises a compact
disc player which reads compact discs on which songs are recorded
in a digital format. The storage may alternatively or additionally
comprise a solid state electronic memory, and/or magnetic storage
such as a number of hard drives and/or magnetic tape drives. Any
combination of these and other storage technologies are
appropriate.
[0060] A compilation generation apparatus 2 is provided, which
includes a central processing unit 3 and a first area of memory 4
which stores a program that provides operating instructions to the
central processing unit 3. The apparatus further includes an input
port 5 which is connected to the memory storage area 1 whereby the
central processing unit 3 can download the song data from the
storage area. In the example, the compilation apparatus 2 is
located in the same room as the memory storage area 1, and is
connected through a conductive cable 6, such as a copper cable.
Optical connections could be used, and it is envisaged that the
storage area may be located in a different geographical area for
access over the telephone network using a modem.
[0061] The compilation generation apparatus 2 further includes an
intermediate memory buffer 7 into which the songs to be compiled
are stored prior to processing, and into which song data produced
by processing the songs can be stored.
[0062] An output port 8 is also provided with enables the final
compilation mix in the intermediate memory 7 to be passed along a
cable 9 to a storage device such as a CD writer 10.
[0063] It will be appreciated that the compilation generation
apparatus may be embodied as a personal computer in which case it
will further include an input device (not shown) for receiving
commands from a user and a display (not shown).
[0064] The apparatus automatically produces a compilation by
performing the steps illustrated in the flow charts of FIGS. 2 to 7
of the accompanying drawings.
[0065] FIG. 2 is a flowchart which gives an overview of the key
steps performed in the compilation method performed by the
apparatus of FIG. 1 of the accompanying drawings.
[0066] In a first step 21, the songs which will make up the
finished compilation mix are selected from those stored in the
first storage area 1. Subsequently, a temporal beat profile is
selected 22 for the finished compilation. This profile provides a
template for the finished compilation and determines the mood of
the finished compilation. Several different profiles may be
provided.
[0067] FIGS. 8(a) to 8(c) illustrate three possible profiles. Each
illustration plots a qualitative value of beats per minute (bpm)
against time over the length of the compilation. In FIG. 8(a), the
bpm starts at a lower value, designated "minimum". This gradually
increases over time to a "maximum" value, and then decreases
towards the end. In FIG. 8(b) the bpm starts at a "maximum" value
and gradually falls. In FIG. 8(c) it starts at a minimum and
gradually increases over time. In each case, the profile covers a
time span from "start" to "stop". The profile can thus be scaled,
for example to correspond to the maximum run-time of a standard
format compact disc.
[0068] Having selected the desired "ideal" profile, the selected
songs are next classified 23 to generate a set of song data. A data
record is generated for each song in which is recorded the average
bpm of the song, its run-time (length) and the location of any
drop-outs in the song.
[0069] In the next step, the songs are allocated 24 to the profile
to determine the order in which the songs will play in the finished
compilation. This is performed by comparing the song data in the
data records with the temporal profile that has been selected to
provide a best fit. This ensures the bpm of the compilation
follows, as closely as possible, the ideal bpm profile.
[0070] After allocating a play order of the songs, the amount of
overlap between songs is calculated and the overlapping portions
are processed 25 to provide a seamless transition between
songs.
[0071] Finally, the processed set of songs is output 26 to the
storage area for recording onto the compact disc by the compact
disc writer.
[0072] Each of the steps is performed automatically and is
illustrated in more detail in the flow charts of FIGS. 3 to 7 and
is described below.
[0073] The step of selecting songs 21 is represented schematically
in FIG. 3 of the accompanying drawings.
[0074] Song selection can be made either manually by a user who
selects from a list or automatically. Initially, the apparatus
queries 31 whether manual or automatic selection is required.
[0075] If manual selection is required, the user is next prompted
32 to select a song. A list of songs from which the selection is to
be made may be displayed or a prompt may be made for the user to
provide a song. For example, following the prompt, the user may
load a compact disc containing the song into the CD player.
[0076] Once a selection has been made 33 (from a list or providing
a disc), the selected song is stored 35 in intermediate memory. The
song itself may be recorded in the memory, or a marker may be
stored which points to the location of the selected song.
[0077] The total run-time of the compilation mix is also requested
34. This may be entered by a user from a prompt or may be a default
value. For example, for a compact disc the default of 74 minutes
may be used. For a compilation for play on a radio show, other
lengths may be stored.
[0078] The apparatus continues to request songs to be selected
until the user indicates that the selection is complete or until
the length of the songs when played end-to-end exceeds the
requested run-time. The selection is then complete. After
selection, a complete set of songs, or markers pointing to the
location of songs, is stored in the intermediate memory. The
temporal beat profile is next calculated or selected, as
illustrated in the flow chart of FIG. 4 of the accompanying
drawings. Again, a profile may be selected automatically or
manually by a user. The apparatus therefore initially queries 41
the selection status. A set of profiles is stored in memory and
identified by an appropriate label, i.e. profile A, profile B,
profile C, etc. j The apparatus prompts 42 the user to select an
appropriate profile by entering the label relating to the profile
from the input device.
[0079] If automatic selection is requested, the profile is either
chosen at random or a default profile is used. This profile is then
stretched/compressed temporally to fit the length of the
compilation required.
[0080] Once a profile has been selected 43 it is stored in memory
or the label identifying the selected profile is recorded 44.
[0081] In the next step, illustrated in more detail in the flow
chart of FIG. 5, the selected songs are analysed to generate a set
of data records. For each song 51 a blank data file is first
produced 52. The average rate of repetition of the dominant beat of
the song is calculated 53 and stored 54 in the data file for the
respective song. The temporal length of the song is calculated and
stored 55, and the temporal location within the song of any
drop-outs is calculated 56 and stored 57 in the data file. After
analysing the first song, the process is repeated 58 until all
songs are analysed and a full set of data files has been
produced.
[0082] The selected temporal profile and the data files are used to
arrange the order of the songs in the completed compilation mix as
best illustrated in the flow chart of FIG. 6 of the accompanying
drawings.
[0083] The profile is first analysed 61 to calculate the ideal
temporal position of the highest and lowest beats per minute. The
profile is then divided 62 into N temporal slices, each slice being
ranked in order by the beats per minute value in the profile.
[0084] The slice having the highest beats per minute is then
matched 63 to the song whose data file indicates it has the highest
beats per minute. Similarly, the slice with the lowest beats per
minute is matched 64 to the song whose data file has the lowest
bpm.
[0085] The remaining songs are then allocated 65 to the profile so
as to provide a "best-fit" solution before the songs are aligned
66.
[0086] If all the songs are the same length, the temporal profile
is divided into equal width slices, the width of the slice being
equal to the length of a song. In that case, songs are fitted
directly to the slots with a small amount of overlap.
[0087] Alternatively, the highest and lowest bpm songs may be
"centred" around the maxima and minima in the profiles. The
remaining songs are then fitted into the profile and the songs are
re-aligned to provide the smallest overlap between songs. The
overlaps may be made equal length. Having arranged the songs into
an approximate run-time order, and roughly overlapped the songs,
the overlapped portions are next processed to provide a seamless
transition between songs. This is illustrated in the flow chart of
FIG. 7 of the accompanying drawings.
[0088] Initially, the first two songs allocated to the sequence are
selected, and the areas of overlap are analysed. The apparatus
checks 71 to see if the bpm value data in the two data files is the
same. If not, then the two overlapping portions are processed 72 by
either time-compressing to speed up or time-stretching to slow down
one or both of the songs until their tempos are matched.
[0089] After ensuring the beats match, the phase of the two end
portions are aligned 73. This is achieved by moving the two songs
temporally until the beats coincide.
[0090] Having aligned the two songs, a fade is then applied to both
songs. The end of the first song is faded out 74, whilst the start
of the next song is faded in 75. This can be achieved by allocating
an amplitude profile to the songs which is stored in the data file
for the song. The data record contains this information alongside
the information indicating where the songs start and finish.
[0091] If the speed of an overlap portion has been adjusted, the
songs are next processed so that the speed returns to its normal
value throughout the song.
[0092] The process is again repeated 76 if required until all the
songs have been processed.
[0093] Finally, the data held in the data files, which provides a
full indication of the temporal alignment, phase adjustment, and
amplitude data for fading is used to record the completed
compilation mix onto the CD in the CD writer. In an alternative,
the details may be written to the CD writer alongside a set of
separate tracks. On play-back, the data file is used to control the
order and timing of play-back so that a full compilation mix is
heard.
* * * * *