MP3 sample rates

[matthewd]

I am doing recordings that sometimes need to be at 48kHz because I am simultaneously filming them and need to be able to drop the audio file into Final Cut. Sometimes the same concerts are wanted as a 192k stream on my website and my question is, does a 48k MP3 playback at the correct pitch. I guess I will soon find out. Obviously it is hassle to have to do 44.1 and 48 versions although ultimately I will probably end up having to do this as soon as someone pops up wanting a CD. Just wondered what others facing similar dilemmas do workflow wise.

Matt

[boojum]

Lower samling rates in MP3 mean lower quality. 48kHz is OK for telephone quality. Your best compromise between quality and size is in the VBR (Variable Bit Rate) encoded files, anything from V2 to V0. I like MP3 for what it is. And the V2 to V0 VBR files are excellent when encoded with the latest release of LAME (LAME MP3 Encoder).

hydrogenaudio.org is when the LAME folks hang out and the fine points are discussed.

Film WAV files at 48kHz are in no way similar to MP3 files at 48kHz.

Cheers

[Liquid360]

Converting something to MP3 Does not alter its pitch, just tosses out a bunch of dynamic and spectrum data.

[rumleymusic]

48kHz is OK for telephone quality

I think you are confusing bit depth with sample rate. You can have a 48kHz or 44.1kHz mp3 at 256kbps, 192kbps etc.

Most all players will be able to distiguish between 44.1 and 48 mp3s and will not play back too fast or too slow.

[didier.brest]

Originally Posted by rumleymusic

I think you are confusing bit depth with sample rate. You can have a 48kHz or 44.1kHz mp3 at 256kbps, 192kbps etc.

I think that you are confusing bit depth with bit rate. MP3 bit depth is 16 bits.

[JonesH]

Originally Posted by didier.brest

I think that you are confusing bit depth with bit rate. MP3 bit depth is 16 bits.

Hmmm. To my understanding lossy compression doesn't have a bit depth as in the case of PCM audio. Every frame is divided into several Spectral bands which are analyzed with regard to sensory masking. Frequencies that are masked are discarded to a degree, as far as can be done without causing readily audible truncation distortion. That also means that lossy compression can't be said to have a bit depth in the same way as PCM audio.
It is quite possible and sometimes maybe preferrable to make mp3:s from 24-bit files. Mp3 files can be both 44,1 and 48 kS/s independent of bitrate.

[didier.brest]

You're right. But a mp3 file ha to be converted in a PCM format, wav for instance, for playback and most mp3 decoders deliver 16 bit samples. MP3 bit depth discussed here.

[JonesH]

Originally Posted by didier.brest

You're right. But a mp3 file ha to be converted in a PCM format, wav for instance, for playback and most mp3 decoders deliver 16 bit samples. MP3 bit depth discussed here.

Perfectly reasonable. Will check link later - thanks!

[matthewd]

Thanks guys - I've found out what I wanted to ie the sample rate of the MP3 does not affect playback. The files are usually from 24 bit wavs and are encoded at 192kbps via the MP3 encoder in Sadie which I think draws upon windows media player for the bit rates

Matt