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Ultra Low Bitrates (REALLY!), 22khz Mono at 16kbps
Freya
post Mar 15 2012, 10:55
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I'm encoding at around 16kbps/24kbps in Mono at 22khz. I'm trying to achieve something like FM radio quality.
Sometimes I get close...

I've tried lame VBR with maxbitrate and more recently have tried ABR but I'm not sure the VBR wasn't better?

Does anyone have any tips on how I can improve my encodes in Lame? Should I add a highpass filter? What do others think of ABR vs VBR? I know ABR is recommended for low bitrates...

I know this is really far away from the usual Lame stuff but I hope people might be able to help a bit anyway!

love

Freya
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Fedot L
post Mar 16 2012, 14:28
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QUOTE (Freya @ Mar 15 2012, 11:52) *
QUOTE (Fedot L @ Mar 15 2012, 10:36) *
QUOTE (Freya @ Mar 15 2012, 10:55) *
I'm trying to achieve something like FM radio quality.
…Does anyone have any tips on how I can improve my encodes in Lame?

To achieve something like FM radio quality, you can code in “mp3 CBR-128 kbps”. Listened to and verified on spectrum analyzer display on music and white noise samples. FM radio frequency band is 30…15000 Hz, “mp3 CBR-128 kbps” frequency band is 30…16000 Hz. If you want to simulate FM radio sound/noise ratio for the best reception conditions too, add hiss at “minus 60 dB” relative to the 0 dB (peak) level of a program listened to.

----
…your reply Fedot! Really made me smile…

Really? And your “trying to achieve something like FM radio quality” (and only mono, I don’t know why, as since 1963, FM is stereo…) by coding in “mp3 16 kbps/24 kbps at 22 khz”, when even in “mp3 24 kbps at 22 khz” the frequency band is 8 kHz, and in “mp3 16 kbps at 22 khz” it’s 5,5 kHz (tested and watched on spectrum analyzer display). Against 15 kHz in FM…
QUOTE (Freya @ Mar 15 2012, 11:52) *
…especially the stuff about adding hiss!

You never heard hiss in FM reception?
QUOTE (onkl @ Mar 15 2012, 15:16) *
If it doesn't need to be MP3, you should give OGG Vorbis and AAC a try. These usually work much more efficient at very low bitrates.

You are quite right. “M4a VBR-16 kbps” stereo gave me 10,5 kHz on HQ music/vocal file, with a good stereo effect and rather good general quality. But far from “simulating FM radio quality”.
QUOTE (DonP @ Mar 15 2012, 15:36) *
Best way to beat the swirlies is narrowing the passband that lame has to encode.

I clearly heard that in HQ files coded in “OGG Vorbis” there was no swirling at much lower bitrates than it was present in “mp3”. On some low frequency music passages I heard swirling in “mp3 CBR-128 kbps”, while it was not in “OGG Vorbis CBR-48 kbps”.
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Posts in this topic
- Freya   Ultra Low Bitrates (REALLY!)   Mar 15 2012, 10:55
- - Fedot L   QUOTE (Freya @ Mar 15 2012, 10:55) I...   Mar 15 2012, 11:36
|- - Freya   QUOTE (Fedot L @ Mar 15 2012, 10:36) QUOT...   Mar 15 2012, 11:52
|- - Porcus   For really low bitrates, you might want to check o...   Mar 15 2012, 12:07
- - KMD   If you just want to reduce the quality dont use an...   Mar 15 2012, 12:30
|- - Freya   QUOTE (KMD @ Mar 15 2012, 11:30) If you j...   Mar 15 2012, 12:47
- - forart.eu   You have to consider Stereo Tool too for mono down...   Mar 15 2012, 14:18
|- - Freya   QUOTE (forart.eu @ Mar 15 2012, 13:18) Yo...   Mar 15 2012, 15:47
- - onkl   If it doesn't need to be MP3, you should give ...   Mar 15 2012, 15:16
- - DonP   QUOTE (Freya @ Mar 15 2012, 05:55) I...   Mar 15 2012, 15:36
|- - Freya   QUOTE (DonP @ Mar 15 2012, 14:36) QUOTE (...   Mar 15 2012, 16:00
|- - DonP   QUOTE (Freya @ Mar 15 2012, 11:00) [ I...   Mar 15 2012, 16:07
- - LithosZA   QUOTE In fact it also needs to be linux and gstrea...   Mar 15 2012, 15:43
- - LithosZA   A few speech codecs that you could try: speex amrn...   Mar 15 2012, 16:01
- - Remedial Sound   Have you tried "--abr 16 -mm." with the ...   Mar 15 2012, 16:01
|- - IgorC   QUOTE (Remedial Sound @ Mar 15 2012, 12:0...   Mar 15 2012, 16:18
- - AndyH-ha   I've done many audiobooks with this. It isn...   Mar 15 2012, 20:54
- - birdie   I'd also suggest HE-AAC or even Skype's SI...   Mar 15 2012, 23:26
|- - NullC   QUOTE (birdie @ Mar 15 2012, 15:26) I...   Mar 16 2012, 04:04
- - Fedot L   QUOTE (Freya @ Mar 15 2012, 11:52) QUOTE ...   Mar 16 2012, 14:28


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