Why does LAME downsample MPEG-1 if bitrate is less than 128 kbps?

[JimmyBarnes]

Usually downsamples from 48 kHz to 32 kHz

One can force it to resample back to 48 kHz - is this bad?

What audible or functional differences are there if sampling rate remains at 32 kHz? (I can't seem to hear any)
JB

[Prosper]

Resampling isn't bad, using such low bitrates is. Resampling just attempts to make the best of a bad situation

[Nic]

Resampling can be pretty bad....depends on range though.

Anyway, if you ask Lame to resample (--resample 48000) & you give it a 48000 file. Then it wont sample down & then back up. But just keep the rate at 48000.

-Nic

[JimmyBarnes]

Originally posted by Nic
Resampling can be pretty bad....depends on range though.

Anyway, if you ask Lame to resample (--resample 48000) & you give it a 48000 file. Then it wont sample down & then back up. But just keep the rate at 48000.

-Nic


If using BeSweet GUI, would this involve the use of Lame2 rather than Lame1? (the Doom9 BeSweet guide uses Lame1 but not Lame2)

JB

[ChristianHJW]

Originally posted by Prosper Resampling isn't bad, using such low bitrates is. .... resampling is always pretty bad if you let Lame do it depending on bitrate. If you decide to resample ( like to 32 KHz for Lame ABR < 96 kbps or to 44.1 KHz < 128 kbps ) use SSRC in 32 bit FP mode ( BeSweet or HeadAC3he ) to do the resampling, never let it be done by Lame routines ....

[Prosper]

My point is just that at such low bitrates, say 80kbps, the quality loss due to resampling would be negligable next to the compression artifacting.

Furthermore, an 80kbps MP3 at 32k would sound better than the same file at 48kHz and 80kbps

[JimmyBarnes]

Originally posted by Prosper
My point is just that at such low bitrates, say 80kbps, the quality loss due to resampling would be negligable next to the compression artifacting.

Furthermore, an 80kbps MP3 at 32k would sound better than the same file at 48kHz and 80kbps

Your reply sounds reasonable, not sure about your title tho...

JB

[ChristianHJW]

Originally posted by Prosper
Furthermore, an 80kbps MP3 at 32k would sound better than the same file at 48kHz and 80kbps ... agreed ... 80 kbps is really not the right ( stereo ) bitrate to use MP3 in any form ( Lame, Xing, FHG, whatever ) .... if you do you in fact should use resampling to 32 KHz ( with SSRC ), or better go for Vorbis and OGM file format ...

[Nic]

(I remember a discussion with Ivan about resampling down for low bitrates when AACEnc first came out. He did not agree with this for AAC. But my memory fails me as to why....)

-Nic