Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

AIFF file header fields

Posted on 2001-06-12
2
Medium Priority
?
276 Views
Last Modified: 2010-04-06
I'm trying to add support for AIFF files (Apple's native PCM audio file format) to a windows program. It works fine in different ways, but other programs which have this support seem to work with a slightly different structure. (Eg: Cool Edit, AWave, Gold Wave). There appear to be 2 less bytes in the COMM chunk before the sampling rate field, and two extra in the SSND field before the sound data.
 The structure I'm using adheres strictly to Apple's AIFF v1.3 documentation, but these other programs concurr on their own structure. I'm using Delphi 3, and here's what I'm doing...
 To write a file, I assign all the field values for the FORM, COMM and SSND chunks to fields in records, byte-reverse each numeric field, and then write the 2 records to disk. To read a file, I read X bytes to a buffer, assign its address to typed pointers, byte-reverse the fields, and get all the info from the records.
 If v1.3 of the format is ancient, or if I'm just stupid and wrong, then can someone please either tell me where to find the docs on the latest version, or fill me in on the proper structure. Following are the record types that I use...

 TrecAIFF_TOF = record
   HeaderCkID : Tarr4CC; { array of 4 char's }
   FileSize   : longint;
   FormatID   : Tarr4CC;
   FmtCkID    : Tarr4CC;
   FmtSize    : longint;
   NmbrChnls  : smallint;
   NmbrFrms   : cardinal;
   NmbrBits   : smallint;
   SmplRate   : extended;
 end;
 PrecAIFF_TOF = ^TrecAIFF_TOF;

 TrecAIFFSgnlHDR = record
   SgnlCkID   : Tarr4CC;    
   SgnlCkSize : longint;
   Offset     : longint;
   BlockSize  : longint;    
 end;                        
 PrecAIFFSgnlHDR = ^TrecAIFFSgnlHDR;


 A thousand thanks (and 50 points) to whoever is able to help!
0
Comment
Question by:HorridMan
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 11

Accepted Solution

by:
robert_marquardt earned 200 total points
ID: 6181167
I would guess that the records are all packed record.

Is "SmplRate: extended;" really correct? Extended is a 10 Byte type whereas Double is a 8 Byte type.
0
 

Author Comment

by:HorridMan
ID: 6189457
 Packed records work perfectly! I would never have thought of that myself. Incidentally, I tried at first using a longint for the SmplRate field, but strangely extended type does work. Goodness knows why they designed it that way.
0

Featured Post

Hire Technology Freelancers with Gigs

Work with freelancers specializing in everything from database administration to programming, who have proven themselves as experts in their field. Hire the best, collaborate easily, pay securely, and get projects done right.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
The uses clause is one of those things that just tends to grow and grow. Most of the time this is in the main form, as it's from this form that all others are called. If you have a big application (including many forms), the uses clause in the in…
Sometimes it takes a new vantage point, apart from our everyday security practices, to truly see our Active Directory (AD) vulnerabilities. We get used to implementing the same techniques and checking the same areas for a breach. This pattern can re…
Want to learn how to record your desktop screen without having to use an outside camera. Click on this video and learn how to use the cool google extension called "Screencastify"! Step 1: Open a new google tab Step 2: Go to the left hand upper corn…
Suggested Courses

636 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question