• Open Menu Close Menu
  • Apple
  • Shopping Bag
  • Apple
  • Mac
  • iPad
  • iPhone
  • Watch
  • TV
  • Music
  • Support
  • Search apple.com
  • Shopping Bag

Lists

Open Menu Close Menu
  • Terms and Conditions
  • Lists hosted on this site
  • Email the Postmaster
  • Tips for posting to public mailing lists
Slow seeking in MP3 files using ExtAudioFile
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Slow seeking in MP3 files using ExtAudioFile


  • Subject: Slow seeking in MP3 files using ExtAudioFile
  • From: Jens Alfke <email@hidden>
  • Date: Tue, 20 Jan 2009 13:46:44 -0800

I'm working on an app that does random-access playback of MP3 and AAC files. It uses ExtAudioFile to read and decode the files. I'm finding that changing the playback position in a file can be very expensive — for example, I open a 20-minute MP3 file, seek to a point about 5 minutes in, and then the first call to ExtAudioFileRead takes over two seconds. During this time, the MP3 decoder is issuing large numbers of fstats 32k reads; it seems to be reading from the start of the file all the way to the point its seeked to.

Is this to be expected? Granted, this is a VBR file so the mapping from time to byte offset isn't linear, but I thought there was a table in the file that served as a TOC. Or is there really no faster way for the decoder to seek than to read MPEG frames until it finds the right time?

(If the latter, is there a way I could produce an external TOC that I could save persistently? I already save metadata about the files, such as a scaled-down waveform preview, that's keyed to the file mod date, so a TOC would be easy to add.)

Thanks,

—Jens

PS: This is in 10.5.6 on a 2.4GHz MacBook Pro, using the internal 160GB disk.

Attachment: smime.p7s
Description: S/MIME cryptographic signature

 _______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:

This email sent to email@hidden

  • Follow-Ups:
    • Re: Slow seeking in MP3 files using ExtAudioFile
      • From: Jeff Moore <email@hidden>
    • Re: Slow seeking in MP3 files using ExtAudioFile
      • From: Markus Fritze <email@hidden>
  • Prev by Date: Re: Speeding HAL plugin loop rate
  • Next by Date: Re: Slow seeking in MP3 files using ExtAudioFile
  • Previous by thread: Mix video and audio
  • Next by thread: Re: Slow seeking in MP3 files using ExtAudioFile
  • Index(es):
    • Date
    • Thread