Wednesday, February 17, 2010

If a train leaves Glasgow playing an MP3 at 60mph and another ....

If I have two copies of a song and one has a bit rate of 256 (CBR, is it?) and other a bit rate of 232VBR, which is better?
If one is better, at what range does it make a difference. (i.e. - if you tell me VBR is better, and I have a choice of 200VBR or 32o CBR(?), which to go for?)


goneforeign said...

Ask Mr Wiki, he'll tell you this:
Audio (MP3)
• 32 kbit/s – MW (AM) quality
• 96 kbit/s – FM quality
• 128–160 kbit/s – Standard Bitrate quality; difference can sometimes be obvious (e.g. lack of low frequency quality and high frequency "swashy" effects)
• 192 kbit/s – DAB (Digital Audio Broadcasting) quality
• 224–320 kbit/s – VBR to highest MP3 quality
• 1,411.2 kbit/s – PCM sound format of Compact Disc Digital Audio
The higher the bitrate the more disc space it will take up, it would be nice to have everything at PCM, [with Macs it's called AIFF] but you'd fill your hard disc very quickly. MP3 is a compression format that shrinks the amount of data in a recorded signal. The higher the bitrate the clearer the definition.
It's analogous to inches per second in tape recording.
Does any of that help? I'm not familiar with CBR.

nilpferd said...

With my limited knowledge I can add the following.. CBR is constant bit rate as opposed to Variable Bit Rate (VBR). CBR means the original signal is sampled consistently over the entire frequency range, ie bits are left out everywhere in equal amounts. This means though that your MP3 file "wastes" some of its data on recording frequencies you can't hear.
VBR basically alters the sampling curve so that certain frequencies are sampled more (the ones you're more likely to notice) and others less (the ones you're less likely to notice), it's roughly the same principle as graphic equalisers. The goal is to achieve a better sound quality for the same file size. Most MP3 recorders have default VBR settings; though you can change these, I'm not sure there's much point. The 192 VBR is supposedly the best compromise between quality and file size, getting up into the 200's leads to a considerable increase in file size.

steenbeck said...

Anybody got EOTWQ for us this week?

tincanman said...