mpgtools.pas

mp3 播放器 delphi 源码

unit MPGTools;
{

MPEG AUDIO TOOLS
(c)1998, 1999 Copyright by Predrag Supurovic

This library gives you tools for manipulating MPEG AUDIO files
(*.mpa;*.mp2;*.mp3). It allows very easy reading and writing of MPEG
data (TAG and HEADER).

Supported formats are MPEG Versions 1, 2 and 2.5, Layer I, II and III.
MPEG TAGs are also supported (ID3v1.1).

Compiled and tested with Delphi 1 and Delphi 3. Received reports
that it sucessfully compiles with Delphi 4.

If you are interested in MPEG file structure take a look at
http://www.dv.co.yu/mpgscript/mpeghdr.htm.


Copyright notice:

All rights reserved by the Author. This source code is freeware if you 
use it to produce freeware applications. You are free to use or 
distribute it as long as it is done in original form. You are not 
allowed to distribute changed source. You must give credits to author in 
your source and executable code produced based on MPGTools, including 
specifying WEB address http://www.dv.co.yu/mgscript/mpgtools.htm.

If you want to use this code in shareware or commercial application you 
are entitled to register it. Registration fee is 30 USD per diferent 
application project. Registered users are free to use code without need 
to explicitly give credits to the author (but it is recommended). 
Registered users may not sell this source code unchanged or changed. 
Registration affects all previous versions of MPGTools.  This means if 
you use any version of MPGTools in your shareware or commercial 
application you must pay for registration.

Users from countries that invaded Yugoslavia or provided direct military 
or diplomatic support, teritory or air space for this puropose are 
required to pay 100 USD for humanitarian aid (does not matter if it is 
useed as freeware or commercial). That money should be sent to author 
who will transfer it to yugoslav humanitarian organizations. People who 
can prove they already sent aid to yugoslav victims o NATO agression are 
free of this obligation.

Send us basic info about your application which uses MPGTools (name,
http/ftp url, archive length, short description) because we may put that
info and link on MPGTools homepage.

Freeware licence does not apply to sysops of SETNet - they are required
to pay 15 USD for using or distributing this source by any mean.

You are wellcome to send comments and suggestions to the Author.  You 
are also wellcome to support Author by donations of literature, tools, 
software or money but it is not reqired.

If you use this code please let us know.


Contact info:

mailto: [e-mail]

Support is available only through email address writen above.  No other 
contact methods are allowed. Remember this *is* freeware project, 
therefore I cannot dedicate too much time and efforts to it. I will do 
my best to respond to any mail regarding this subject.

Updated info, new versions, supporting documentation and demo
applications in source code are available at
http://www.dv.co.yu/mpgscript/mpgtools.htm.


Author:
Predrag Supurovic
Dimitrija Tucovica 44/84
31000 Uzice
YUGOSLAVIA

Author's personal homepage: http://www.dv.co.yu/broker/


Beta test

Many thanks to Jean Nicolle, who voluntarily betatests this code and 
comes with good and valuable ideas almost every day.


Versions:

  1.8 (November 12, 1999.)
  - This source is no longer freeware for commercial use (shareware and
    commercial applications). It remains freeware for use in freeware
    applications.
  - In one of previous releases I announced that TMPEGAudio class is
    finished and that there is nothing left to improve. Well, I was wrong.
    This time new ideas came, and also I received few very valuable
    suggestions from users.
  - IMPORTANT ISSUE! Limited support to VBR (Variable BitRate) MP3 files
    proposed by Xing included. Library recognizes if file is VBR, and
    also tries to calculate duration, which may not be precise due to
    nature of this type of files). Many thanks to Eric from Xing Tech
    support who has been great help.
  - One notice: some time ago I had demand to expand FileName property to
    support long strings. I declined since it was complicated to implement.
    Recently, I did some tests and it seems to me that Windows reports error
    if you try to copy file with name longer than about 70 characters
    including path. MAX_PATH global agrees with this value. It seems, FileName
    property 255 characters long is more than sufficient.
  - In meanwhile I got new info about MPEG header specs. There were some
    wrong informations I had before about rarely used formats. Now it is more
    accurate.
  - Due to my efforts to make this library as much user friendly as possible I
    even added some predefined dialogs. Later I realized that including Dialogs
    unit in uses clausule enlarged compiled exe file a lot. It does not affect
    Windows applications that already use dialogs, but there are some users
    (including me) who use this library for developing DOS prompt applications
    and do not require such things like windows dialogs. They noticed monstruous
    enragement of their applications. I think I found a solution. There is
    special compiler directive $DEFINE UseDialogs. If UseDialogs is defined,
    compiler will include everything necessary for using dialogs. If it is not
    defined, Dialogs will be excluded from comilation an therefore executable
    will be significantly shorter. By default this directive is defined and you
    may find it as first thing in interface section of this unit. 
  - Import and export to PLS files added. PLS files are second format
    supported by WinAmp, and, as I understood it is also widely used.
  - mctComplexMacro type added. It allows you to define a macro as a string
    containing other macros. May be very powerful. This does not work in
    Delphi 1.
  - TMPEGAudio.SearchExactFileName property added (only for 32bit Delphi).
  - TMPEGAudio.SearchDrives property added (only for 32bit Delphi);
  - TMPEGAudio.FileNameShort property added. Returns DOS8+3 formated file name.
    Works only in 32bit Delphi.
  - Two new macros added (%ExtractedArtist% and %ExtractedTitle%). They are
    important for those who use tagless MPEG files. They usually store artist
    and title info in filename. These macros will try to extract that data. Global
    variable FileNameDataDelimiter is used as delimiter between artist and
    title. By default, this delimiter is '-' and it is supposed that file
    naming scheme is like Artist - Title.mp3 which is mostly the case.
  - TMacroDefinition class added. It allows easy adding new macros
    and assigning default values and functions that should be called
    to get value to replace macro. It also allows changing default
    values and functions for built in macros.
  - TMPEGAudio.FGetMPEGValue method removed. It was used internaly and it's
    of no use since now we have TMacroDefinition class.
  - TMPEGAudio.IsTagged readonly property added. It returns true if valid
    TAG exists in MPEG audio file.
  - TMPEGAudio.FFileDateTime property changed to be a method.
    This way I avoided redundancy.
  - TMPEGAudioList.ExportToWinAmpList and
    TMPEGAudioList.ExportToMPEGDataFile methods parameter syntax
    changed. SelectedOnly parameter added. It allows exporting only
    selected items.
  - Added support for Windows Regional settings. It now affects formatting
    of data when converted to string (TMPEGAudio.Textilize method).
  - %FileTime% macro default length changed to eleven characters
  - %FileDateTimeForSort% macro added. It shows file date and time
    formated suitable for sorting (yyyymmddhhmmss).
  - %DurationForm% macro changed not to show leading zeros for hours.
    Leading zero may be added by formatting (i.e. %DF,R,%,0)
  - %FilePathName% macro added. It concatenates file path and name so they may
    be formated as single item.
  - %GuessedArtistTitle% macro added. It tries to read values from TAG, filename
    and UnknownArtist/UnknownTitle properties in that order.
  - Lots of work has been done to intercept error conditions and make them
    easy available to application. This is much better now.
  - TMPEGAudio.OnReadError property added. This event will be trigered when
    error occures while reading MPEG audio file. By default it is set to
    MPEGFileLoadError function also provided in this unit. You can always
    change TMPEGAudio.OnReadError to point to some your function.
  - ShowMPEGAudioReadError property added to TMPEGAudioList. TMPEGAudioList
    uses internal TMPEGaudio object you cannot affect, but you will probably
    need to change their onReadError property. Thats what is
    TMPEGAudioList.ShowMPEGAudioReadError for. It's value will be assigned to
    OnReadError property of each internal TMPEGAudio object created. Default
    value is pointer to MPEGFileLoadError function provided in this unit.
  - AutoLoad property added. It affects behaviour of FileName.
    property. If True, it will cause FileName to behave like it did in
    previous versions. If False, data will not be loaded automatically.
    It is true by default.
  - LoadData method added. When called, it loads data, and returns error
    value (see OnLoadError)
  - TMPEGAudioList.UnknownArtist and TMPEGAudioList.UnknownTitle
    properties added.
  - TMPEGAudioList.MPEGAudioUnknownArtist and
    TMPEGAudioList.MPEGAudioUnknownTitle properties added.
  - WinAmp Genre codes added
  - Lots of monor changes has been made. I lost track to lost of them. I
    tried and I think I suceded not to change function interface except
    where it had to be done. You will probably notice one or two functions
    using different parameters, but all those changes are minor (actually,
    one function surfed total change, and that is because it was totaly
    unusable with previous definition).

  1.7. (5. October 1998.)

  - Another MPEG recognizing bugfixes. I must notice that all
    bugfixes deal with trashed MPEG files (it means, files
    containing non MPEG data at the begining). I test unit on
    MPEG files I created and they are all correct, but it seems
    on the Internet you may find everything. Thus, you, users of
    this unit are very important for bugfixing. As much MPEGs you
    try with this code, sooner we will find all posiible bugs.

  - Jean Nicolle showed up as an excellent beta tester. Not just
    he is very good in detecting bugs, he also makes very
    valuable suggestions. Therefore, I am appointing him as the
    first official MPGTools betatester.

  - FileDetectionPrecision property added to both TMPEGAudio and
    TMPEGAudioList class. It limits how many bytes of file will
    be searched for MPEG frame headers. That means you now may
    not allow object to search whole file attempting to find out
    if it is MPEG audio. I do not reccomended to use this, but
    it's here. It may be useful.

  - Behaviour of TMPEGAudio.Textilize method changed. NOW IT DOES NOT
    affect contents of TMPEGAudio.Macro and TMPEGAudio.Text properties.
    I found out that it was not suitable approach.

    TMPEGAudio.Textilize method may be called very often for other
    reasons (i.e. sorting utility) which should not affect contents
    of these two properties. Everything else regarding TMPEGAudio.Macro
    and TMPEGAudio.Text stays the same: whenever you change
    TMPEGAudio.Macro or any of writeable properties contents of the
    TMPEGAudio.Text will be updated automatically.

  - Bug in TMPEGAudio.Textilize fixed: when I changed Textilize not to
    alter contents of Macro and Text properties, I left Textilize read
    contents of Macro instead of string passed as parameter.

  - TMPEGAudio.FReadData, TagTMPEGAudio.WriteTag and
    TMPEGAudio.RemoveTag methods are changed. Now they are functions
    and returned result is error code.

  - Added types: TListSortCompare and TListSortCompareFunc.
    Added properties: SortMethod, UserSortCompareFunc property and
    SortMacro. Added methods: InternalSortCompareFunc,
    DoUserSortCompareFunc and DoSort. Now, user may specify if
    he wants list not to be sorted, to be sorted internaly (sort key
    specified in SortMacro) or externaly, by user defined function.

  - Added property: TMPEGAudioList.SortDirection, and few
    methods changed to support it. Now, user may set sort direction
    regardless of SortMethod used and there is no need for user
    functions for ascending and descending order.

  - I've detected bug with TMPEGAudioList sorting, but cannot fix it yet.
    To reporoduce The Bug, run MPGLIST demo, load some files to the list,
    set sort method to Internal, and enter '%aaa%' in the edit box. Click
    on sort button several times. You will notice that it sorts items
    erratically. It seems problem is in QuickSort function (which I took
    from source of TList object). Point is that %aaa% is not existing macro.
    Therefore, Textilize function does not convert it but returns same
    string. That is normal. Thus, TMPEGAudioList.InternalSortCompareFunc
    always compares same string regardless if items are different or not.
    It will always return zero result of comparation. That is also ok,
    and it means that QuickSort will think list is already sorted.
    But, there is a problem. For some reason QuickSort behaves
    unpredictable in such situation. It works well when it has to
    sort already sorted list. I assume, that, algorithm presumes if
    all items are equal there is no need to take care if their order
    will be corupted. I have to find a way to check if list is already
    sorted properly, and break Quicksort before it makes mess. I must
    admit I am not familiar with Quick Sort algorithm.

  - Help wanted. I received report that when compiling unit with
    Delphi 4 it shows warning that TMPEGAudioList.Create constructor
    should be overriden. I do not receive such warning in Delphi 3
    (I do not have Delphi 4). When I tried to override it, Delphi
    reported method is static and cannot be overriden. If anyone can
    provide solution I would appreciate it.


  1.6 (8. Sept. 1998)