Get Image File Information using MediaInfo library in Inno Setup Pascal Script

Question

I have been trying for more than two days to get JPEG Image and MP4 Video File Information using MediaInfo.DLL in my Pascal Script.

But I keep getting error

Runtime Error (at 6:366) - Access Violation at address 0042FD23. Read of address 8065241E.'

The error mostly points to (at 6:366).

I can't think what problem is causing this exception when trying to get Media Information using MediaInfo.DLL.

The code I added to my Script:

[Files]
Source: Lamborghini_Aventador.jpg; DestDir: {tmp}; Flags: dontcopy
Source: MediaInfo.dll; DestDir: {tmp}; Flags: dontcopy

[Code]
#ifdef UNICODE
type
  PWideChar = WideString;
#endif

const
  StreamKind_Image = 5;
  InfoKind_Text = 1;

function MediaInfo_New: Cardinal;
  external 'MediaInfo_New@{tmp}\MediaInfo.dll stdcall delayload';
function MediaInfo_Open(Handle: Cardinal; File__: PWideChar): Boolean;
  external 'MediaInfo_Open@{tmp}\MediaInfo.dll stdcall delayload';
function MediaInfo_Get(Handle: Cardinal; StreamKind: Integer; StreamNumber: Integer; Parameter: PWideChar; KindOfInfo: Integer; KindOfSearch: Integer): PWideChar;
  external 'MediaInfo_Get@{tmp}\MediaInfo.dll stdcall delayload';

procedure RetrieveImageInformation;
var
  IHandle: Cardinal;
  Width: PWideChar;
begin
  ExtractTemporaryFile('Lamborghini_Aventador.jpg');
  ExtractTemporaryFile('MediaInfo.dll');
  IHandle := MediaInfo_New();
  MediaInfo_Open(IHandle, PWideChar(ExpandConstant('{tmp}\Lamborghini_Aventador.jpg')));
  Width := MediaInfo_Get(IHandle, StreamKind_Image, 0, 'Width', InfoKind_Text, 0);
  Log('Width of the JPEG Image: ' + PWideChar(Width) + '.');
end;

The line which the exception is generating is:

Width := MediaInfo_Get(IHandle, StreamKind_Image, 0, 'Width', InfoKind_Text, 0);

I expected that the compiler output will be Width of the JPEG Image: 1920.

I use latest version of Unicode Inno Setup Compiler (5.5.9 - U)

Thanks in advance for your important help.

Where did you obtained those DLL Calls for `MediaInfo.DLL`? Are they obtained from the Delphi Example comes with it? — GTAVLover, Aug 23 '16 at 01:45
Yes @GTAVLover......... I think they're fine.......Your recommendation is also fine.......Just what I want is to get CMD Output via `LoadStringFromFile`. :-) — Blueeyes789, Aug 30 '16 at 15:44

Martin Prikryl · Answer 1 · 2019-07-02T07:35:23.057

2

I do not think you can call a function that returns a pointer to a string (character buffer) from Inno Setup Pascal Script.

But you can hack it like this:

Declare the function as if it returns Cardinal;
Use some available function that takes a pointer and copies it to another pointer. Declare the source pointer as Cardinal and the target pointer as string. One such function is the StrCpyN.

function MediaInfo_Get(
  Handle: Cardinal; StreamKind: Integer; StreamNumber: Integer;
  Parameter: string; KindOfInfo: Integer; KindOfSearch: Integer): Cardinal;
  external 'MediaInfo_Get@{tmp}\MediaInfo.dll stdcall delayload';

function StrCpyN(S1: string; S2: Cardinal; Max: Cardinal): Cardinal;
  external 'StrCpyNW@shlwapi.dll stdcall';

var
  P: Cardinal;
  S: string;
begin
  P := MediaInfo_Get(IHandle, StreamKind_Image, 0, 'Width', InfoKind_Text, InfoKind_Name);
  S := StringOfChar(' ', 1024);
  StrCpyN(S, P, Length(S) - 1);
  S := Trim(S);
  ...
end;

The code requires Unicode Inno Setup (the only version as of Inno Setpu 6).

edited Jul 02 '19 at 07:35

answered Aug 28 '16 at 15:21

Martin Prikryl

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It seems bit hard, how can I declare `StrCpyN` ? – Blueeyes789 Aug 30 '16 at 08:17
Sorry, I've forgot the `StrCpyN` declaration. Added now. – Martin Prikryl Aug 30 '16 at 11:53
This works well, but I can't sure will it work well in all Windows versions..... :-( – GTAVLover Aug 30 '16 at 15:05
Why do you think this won't work on all versions of Windows? – Martin Prikryl Aug 30 '16 at 15:09
Is `StrCpyN` exist in all Versions of ShlwAPI.DLL including W. XP and 98? – GTAVLover Aug 30 '16 at 15:34
@MartinPrikryl thx for giving this hacking method, but I don't see any performance difference between getting those info using MediaInfo Library and retrieving them (like -GTAVLover said), using Command Line and getting CMD Output via `LoadStringFromFile.` That's Why? – Blueeyes789 Aug 30 '16 at 15:38
The `StrCpyN` is definitely available on Windows XP too. Not sure about 98. Do you even expect the Media Info to run on 98? – Martin Prikryl Aug 30 '16 at 15:43
To me a hack is calling an external exe to retrieve media file information. Anyway, I was just answering your question (why the `MediaInfo_Get` is crashing). Chose the solution you like. – Martin Prikryl Aug 30 '16 at 15:44
Yes....... Is the crashing of the function `MediaInfo_Get` caused the shown exception ? – Blueeyes789 Aug 30 '16 at 15:47
@MartinPrikryl I just asked..........It is good to hear `StrCpyN` exists in XP too.........Thank you for the given Important Information about `StrCpyN` Function.......... ;-) – GTAVLover Aug 30 '16 at 15:49
No the exception is caused by Inno Setup Pascal Script not being able to handle the `PChar` returned by the function. Not by the function itself. – Martin Prikryl Aug 30 '16 at 15:50
I finally like to know will this work on both Unicode and Ansi Inno Setup Compiler. – Blueeyes789 Aug 30 '16 at 22:35
As is, the code works on Unicode version only. While the code can be made running on Ansi version, you should not use the Ansi version nowadays anymore. – Martin Prikryl Aug 31 '16 at 06:05

GTAVLover · Accepted Answer · 2016-08-23T02:21:49.510

You can use the MediaInfo Command Line Interface with Inno Setup Ansi or Unicode Version.

Usage Example:

[Files]
Source: MediaInfo.exe; DestDir: {tmp}; Flags: Dontcopy

[code]
function InitializeSetup(): Boolean;
var
   ErrorCode: Integer;
begin
   ExtractTemporaryFile('MediaInfo.exe');
   ShellExec('Open', 'MediaInfo.exe', ExpandConstant('"YourFileName.mp4" --LogFile="YourFileName Prperties.log"'), ExpandConstant('{tmp}'), SW_HIDE, ewWaitUntilTerminated, ErrorCode);
   if SysErrorMessage(DLLGetLastError) = SysErrorMessage(0) then
   Result := True;  
end;

Now, navigate to the Inno Setup Temporary Directory as Administrator using Run (Windows Key + R) Command and see your Media Information Log File exists there which contains the Information about the File you given in the Command.

Get Image File Information using MediaInfo library in Inno Setup Pascal Script

2 Answers2

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