Resample UP = lower quality than original!? -Sound Forge - PC

Subject:Resample UP = lower quality than original!? Posted by: Nathan323 Date:11/1/2005 5:05:22 PM Howdy all, I have some MP3's that have a bit rate of 160kbps, & sample rate of 22kHz. I want to convert these files to 44kHz (mainly because CDRWIN does not recognize them at the lower sample rate). When I do this (saving as an MP3 with exactly the same attributes except a 44kHz sample rate), the resulting MP3 sounds more 'muffled' than the original file. Has anyone had this problem? Any help would be much appreciated. Thanks, Nathan
Subject:RE: Resample UP = lower quality than original Reply by: Chienworks Date:11/1/2005 5:23:23 PM Makes sense. Any change you make to a file will degrade the signal. There's no way to get back what's been lost, and you can't even break even. Kinda like Newton's laws of thermodynamics. Also, with your process, you are requiring the encoder to squeeze twice as much data in the same space. You should be saving at 320kbps in order to have the same amount of compression. Better yet, save it as uncompressed WAV until you're done burning. That way you shouldn't have any noticeable degradation at all. Message last edited on11/1/2005 5:24:05 PM byChienworks.
Subject:RE: Resample UP = lower quality than original Reply by: Nathan323 Date:11/1/2005 7:00:28 PM Yeh thats a good idea with the wav's - cheers mate.
Subject:RE: Resample UP = lower quality than original!? Reply by: ForumAdmin Date:11/2/2005 7:19:31 AM More specifically, the 22.05 kHz file can reproduce frequencies up to 11.025 kHz (the Nyquist frequency). Resampling to 44.1 kHz means the file is able to reproduce frequencies up to the new Nyquist frequency of 22.05 kHz. But resampling alone doesn't introduce new frequency content. In other words, resampling by itself won't necessarily "degrade the signal" (that's arguable depending on the resampler quality). But the resampled file is still band-limited to the original 11.025 kHz. With or without the resampling, re-compressing with any lossy codec (mp3 in this case) will only further degrade the signal. Ideally, you'd want to keep an uncompressed copy of the source material around for editing and only render to mp3 for deliverables. J. Message last edited on11/2/2005 7:21:13 AM byForumAdmin.
Subject:RE: Resample UP = lower quality than original!? Reply by: Geoff_Wood Date:11/3/2005 12:25:09 PM Why are you wanting to upsample mp3 files ? CDR-WIN is for writing to Audio CDs (or was when I was a regular user !), so the source file should be 44k1 16 bit linear pcm (=WAV), so why not convert to that ? geoff

Subject:Resample UP = lower quality than original!?

Posted by: Nathan323

Date:11/1/2005 5:05:22 PM

Howdy all,
I have some MP3's that have a bit rate of 160kbps, & sample rate of 22kHz. I want to convert these files to 44kHz (mainly because CDRWIN does not recognize them at the lower sample rate). When I do this (saving as an MP3 with exactly the same attributes except a 44kHz sample rate), the resulting MP3 sounds more 'muffled' than the original file.

Has anyone had this problem? Any help would be much appreciated.

Thanks, Nathan

Subject:RE: Resample UP = lower quality than original

Reply by: Chienworks

Date:11/1/2005 5:23:23 PM

Makes sense. Any change you make to a file will degrade the signal. There's no way to get back what's been lost, and you can't even break even. Kinda like Newton's laws of thermodynamics.

Also, with your process, you are requiring the encoder to squeeze twice as much data in the same space. You should be saving at 320kbps in order to have the same amount of compression. Better yet, save it as uncompressed WAV until you're done burning. That way you shouldn't have any noticeable degradation at all.

Message last edited on11/1/2005 5:24:05 PM byChienworks.

Subject:RE: Resample UP = lower quality than original

Reply by: Nathan323

Date:11/1/2005 7:00:28 PM

Yeh thats a good idea with the wav's - cheers mate.

Subject:RE: Resample UP = lower quality than original!?

Reply by: ForumAdmin

Date:11/2/2005 7:19:31 AM

More specifically, the 22.05 kHz file can reproduce frequencies up to 11.025 kHz (the Nyquist frequency). Resampling to 44.1 kHz means the file is able to reproduce frequencies up to the new Nyquist frequency of 22.05 kHz. But resampling alone doesn't introduce new frequency content.

In other words, resampling by itself won't necessarily "degrade the signal" (that's arguable depending on the resampler quality). But the resampled file is still band-limited to the original 11.025 kHz.

With or without the resampling, re-compressing with any lossy codec (mp3 in this case) will only further degrade the signal.

Ideally, you'd want to keep an uncompressed copy of the source material around for editing and only render to mp3 for deliverables.

J.

Message last edited on11/2/2005 7:21:13 AM byForumAdmin.

Subject:RE: Resample UP = lower quality than original!?

Reply by: Geoff_Wood

Date:11/3/2005 12:25:09 PM

Why are you wanting to upsample mp3 files ? CDR-WIN is for writing to Audio CDs (or was when I was a regular user !), so the source file should be 44k1 16 bit linear pcm (=WAV), so why not convert to that ?

geoff