Solved

Multimedia API + Delphi

Posted on 1997-05-30
2
441 Views
Last Modified: 2013-12-03
Do you know if it is possible to play a waveform using selective speed, or to play it in reverse direction?
I am using Delphi and MM API.I found the function waveOutGetPlaybackRate but I am not sure for its use. But anyway it asks for the handle of the waveform-audio output device.How do I get that handle if I didn't use the standart waveOutOpen?
I am using instead a Delphi 3.0 MediaPlayer component, which does not return (as far as I know) that handle.
0
Comment
Question by:kyriacos
2 Comments
 
LVL 23

Accepted Solution

by:
chensu earned 100 total points
ID: 1397741
You can use waveOutSetPlaybackRate to change the playback speed. But not all devices support playback rate changes. To determine whether a device supports playback rate changes, use the WAVECAPS_PLAYBACKRATE flag to test the dwSupport member of the WAVEOUTCAPS structure (filled by the waveOutGetDevCaps function). There is another limited method. Load the wave file into a buffer, change the sample rate of the WAVEFORMAT (e.g., from 11025 to 44100) before using waveOutWrite to play it.

To play a waveform in reverse direction, load the wave file into a buffer, reverse the sample before playing it. There is an example C code called 'reverse' in Windows SDK.

I think you have to use waveOutOpen to get the handle.

0
 
LVL 1

Author Comment

by:kyriacos
ID: 1397742
I found the idea of changing sample rates very nice...
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

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

zlib is a free compression library (a DLL) on which the popular gzip utility is built.  In this article, we'll see how to use the zlib functions to compress and decompress data in memory; that is, without needing to use a temporary file.  We'll be c…
For most people, the WrapPanel seems like a magic when they switch from WinForms to WPF. Most of us will think that the code that is used to write a control like that would be difficult. However, most of the work is done by the WPF engine, and the W…
This is Part 3 in a 3-part series on Experts Exchange to discuss error handling in VBA code written for Excel. Part 1 of this series discussed basic error handling code using VBA. http://www.experts-exchange.com/videos/1478/Excel-Error-Handlin…
Internet Business Fax to Email Made Easy - With  eFax Corporate (http://www.enterprise.efax.com), you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, f…

863 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

Need Help in Real-Time?

Connect with top rated Experts

28 Experts available now in Live!

Get 1:1 Help Now