realdanceradio
New Member
What birate do you broadcast in? I've found very little difference in 96kps and 128kps.
Best birate?
- Thread starter realdanceradio
- Start date
A number of radio stations broadcast in multiple bitrates. You probably wouldn't notice much of a difference between 96 and 128kps listening on a mobile device for instance, but run it through a spectrum analyser you will soon see what frequencies you're missing out on. Listening to it through high quality speakers and you'd probably notice somewhat ion a difference.
my personal preference (music based station playing EDM) is 192k MP3 for fixed device listening (i.e something you would connect to your hi fi) and 96k AAC-LC for mobile listening.
I do sometimes listen to Radio Maria NL which uses 128k MP3 but can hear all the artifacts on music based content; not sure if I would put up with a music based station on 96k MP3 for very long; almost as bad as the "youth/dance" stations on DAB now using 80k mono on the obsolete MP2 encoding...
You either need to stream both from your playout or use a transcoder such as liquidsoap to send both at once (use the highest bitrate stream as a source for the lower ones).
The lower bitrate AAC+ filters off high frequencies above 12 KHz making it less quality than analogue Band II FM broadcast! Might be tolerable for speech or a replacement for a LF/MF/HF analogue service on AM but anyone below their late middle age is likely to notice the loss of treble.
I do sometimes listen to Radio Maria NL which uses 128k MP3 but can hear all the artifacts on music based content; not sure if I would put up with a music based station on 96k MP3 for very long; almost as bad as the "youth/dance" stations on DAB now using 80k mono on the obsolete MP2 encoding...
You either need to stream both from your playout or use a transcoder such as liquidsoap to send both at once (use the highest bitrate stream as a source for the lower ones).
The lower bitrate AAC+ filters off high frequencies above 12 KHz making it less quality than analogue Band II FM broadcast! Might be tolerable for speech or a replacement for a LF/MF/HF analogue service on AM but anyone below their late middle age is likely to notice the loss of treble.
LG73
New Member
With all due respect to Alex, I think the comments about AAC+ (these days better known as HE-AAC) are misleading.
All HE-AAC streams rely on a technology called SBR (Spectral Band Replication), a brilliant system invented by a Swedish company called Coding Technologies which was first publicly revealed in 2001. It became an official MPEG standard in 2003. SBR is used when streaming in any HE-AAC variant regardless of bit-rate or HE-AAC version. The main stream encoder does its job at half the desired end result sampling rate. In the case of most typical radio streams, that main stream is done at 22.05kHz sampling rate which makes it impossible for anything above 11kHz in the audio band to be included in the base stream. To avoid possible aliasing the audio going into the main encoder is typically filtered so nothing above 10kHz goes in.
Magic then happens at the decoding end. SBR includes a side stream of hints for the decoder to replicate the highs that would otherwise be there if the stream was done at 44.1kHz sampling rate. Highs from 10kHz to 20kHz get put back in to the audio by the SBR part of the decoder for playback. It sounds very convincing and seems to be full bandwidth audio even though the highs are a replication. Subjectively HE-AAC can sound better than most analogue FM stereo reception since it's immune to multipath interference, the effects of pre-emphasis at the transmission end, pilot tone leakage and other nasty things that can adversely affect FM stereo radio reception.
I currently stream my stations in 64k HE-AACv1 format and 180k AAC format. 192k mp3 is not bad but I think you'd get better results with 160k or higher AAC if you're striving for audiophile quality.
We briefly had DAB here in Canada. Most stations in Vancouver streamed at 224kbps stereo and some at 192kbps stereo. CBC Radio One streamed in 128kbps mono. MPEG 1 layer 2 sounded very nice at high bit-rates (the 224k stereo DAB broadcasts sounded great) but is a magnitude worse than mp3 at lower bit-rates. I can only imagine how painful DAB must sound in 80k mono! I picked up a portable DAB receiver when they were blown out at Radio Shack for 50% off and briefly enjoyed the amazing quality until the total market failure of DAB in Canada resulted in the shutdown of the service. The receiver's not a total write-off as it also has an analogue FM tuner.
I hope the above makes sense and helps in understanding the possibilities with HE-AAC streaming.
Cheers,
Philip
All HE-AAC streams rely on a technology called SBR (Spectral Band Replication), a brilliant system invented by a Swedish company called Coding Technologies which was first publicly revealed in 2001. It became an official MPEG standard in 2003. SBR is used when streaming in any HE-AAC variant regardless of bit-rate or HE-AAC version. The main stream encoder does its job at half the desired end result sampling rate. In the case of most typical radio streams, that main stream is done at 22.05kHz sampling rate which makes it impossible for anything above 11kHz in the audio band to be included in the base stream. To avoid possible aliasing the audio going into the main encoder is typically filtered so nothing above 10kHz goes in.
Magic then happens at the decoding end. SBR includes a side stream of hints for the decoder to replicate the highs that would otherwise be there if the stream was done at 44.1kHz sampling rate. Highs from 10kHz to 20kHz get put back in to the audio by the SBR part of the decoder for playback. It sounds very convincing and seems to be full bandwidth audio even though the highs are a replication. Subjectively HE-AAC can sound better than most analogue FM stereo reception since it's immune to multipath interference, the effects of pre-emphasis at the transmission end, pilot tone leakage and other nasty things that can adversely affect FM stereo radio reception.
I currently stream my stations in 64k HE-AACv1 format and 180k AAC format. 192k mp3 is not bad but I think you'd get better results with 160k or higher AAC if you're striving for audiophile quality.
We briefly had DAB here in Canada. Most stations in Vancouver streamed at 224kbps stereo and some at 192kbps stereo. CBC Radio One streamed in 128kbps mono. MPEG 1 layer 2 sounded very nice at high bit-rates (the 224k stereo DAB broadcasts sounded great) but is a magnitude worse than mp3 at lower bit-rates. I can only imagine how painful DAB must sound in 80k mono! I picked up a portable DAB receiver when they were blown out at Radio Shack for 50% off and briefly enjoyed the amazing quality until the total market failure of DAB in Canada resulted in the shutdown of the service. The receiver's not a total write-off as it also has an analogue FM tuner.
I hope the above makes sense and helps in understanding the possibilities with HE-AAC streaming.
Cheers,
Philip