Mailing Lists: Apple Mailing Lists

Image of Mac OS face in stamp
 
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Weird problem with GetMediaSample()?



Hi,

I am having a problem with AAC and Lossless files, but other types (AIFF, MP3, etc.) work just fine.

The problem I'm having is that after reading in the file, converting it to 32-bit float, writing it to a new file (using CoreAudio), and playing it back, small segments of the audio file are missing. There are no gaps, so it sounds sort-of like a CD that isn't tracking very well. It also appears to be mostly at the very beginning and end of the file.

When I analyse my sound converter fill buffer proc, I notice the call to GetMediaSample() returns weird results. For instance:

At the beginning/end of reading an AAC file, I'll get 21 samples returned but only 147 bytes returned. Compared to the middle of the file I'll have 1 sample returned with 358 (actual byte count varies a little bit) bytes returned. Or 2 samples with 714 bytes. It is as if GetMediaSample() did read and convert but the byte count is completely out of sync.

Also, it's reading in tiny sizes (300 bytes or less???). My converter proc is called 9669 times for a 3.6MB file. Compared to 161 for a 4.6MB MP3 file or 483 times for a 40MB aiff file.

I have based my code on the ConvertMovieSndTrack sample code.

Any ideas? Thanks.

-- John
_______________________________________________
Do not post admin requests to the list. They will be ignored.
QuickTime-API mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quicktime-api/email@hidden

This email sent to email@hidden


Visit the Apple Store online or at retail locations.
1-800-MY-APPLE

Contact Apple | Terms of Use | Privacy Policy

Copyright © 2007 Apple Inc. All rights reserved.