Hi,

I'm new to audio encoding. I've downloaded the latest Winamp 5.33 (WinXP) and am experimenting with its MP4/HE-AAC encoder. I want to set up a freeBSD server to stream my CD collection, so I want to encode my CDs using an efficient low-bitrate format. I have some questions:

1. I tried to encode my CD using MP4/HE-AAC encoder that comes with Winamp (I have never installed any plug-ins). Using the 24kbps setting, I encoded a file (song.mp4). When I play it in Winamp, it shows 24kbps and ~32KHz. It sounds pretty bad compared to the sky.fm aacplus streams, which shows 24kbps but ~44KHz. I'm thinking maybe the lower sampling rate is the cause of the poorer sound quality? How can I encode it @ 24kbps with 44KHz? (I see no settings in Winamp to do so)

2. Actually I'd rather make only 1 copy of my CD. Now I have to make 2, one in a higher bitrate for better quality listening at home (currently I'm using 192kbps WMA, but I am thinking of switching to 192kbps LC-AAC). Since I also want to make a streaming server, I also want a low bitrate copy. Since sky.fm sounds pretty good to me, I'm thinking of going HE-AAC (aacplus v1) 24kbps. Anyone has any suggestions of what format/how I should encode in this scenario? Should I use the encoder from Winamp? Nero?

3. I also have some questions about setting up icecast2 to stream aacplus, since I'm also very new to freeBSD. The tutorials in icecast.org are rather unclear to me (especially since I want to use aacplus). Any links to any tutorial or advice would be greatly appreciated.

Thank you!

1. 44100hz should be available for 24kbps aacPlus, check the settings again.

2. Depending on which way you want to go..
-ezstream (for streaming pre-encoded content, or transcoding on the fly)
-winamp + shoutcast dsp OR oddcast3 (for streaming live content, as via winamp's playlist, since you are using icecast oddcast3 is the easier choice here)

3. As long as your stream source (ezstrea, oddcast, etc.) knows your icecast2 password, IP address, and you give it a proper mount point (/stream.aac or /stream.aacp) it should connect no problem.

I recommend that beginners have the server on the same machine as the source. That way you can just connect to localhost and avoid any network problems untill you understand how to use the software. If this is a private stream, be sure to disable the YP listing and password your stream.

Good luck

Thanks for your reply.

For #1, the settings I see in Winamp are:

Under CD Ripping>Enocder:

Encoding Format: this is where i choose stuff like AAC, MP4, MP3, FLAC, etc. I chose "MP4/aacPlus (HE-AAC) Encoder v 1.24"

aacPlus Encoder Options:
Bitrate: I chose 24kbps here
Channel Mode: Stereo/PS/Mono, I chose Stereo here
Advance Options: Tune for Speech, unchecked


I don't see other places I can set the kHz... can someone please let me know where I can set this option?

At that bitrate, Parametric Stereo will sound better than Stereo.

I just tried your suggestion and PS does sound better than just HE at 24kbps. Also, now winamp shows "24kbps 44kHz" for the PS instead of "24kbps 32kHz" for the HE only file. So maybe sky.fm is using PS HE-AAC (aacplus v2). But shouldn't there be a setting where I can set the kHz?



Also, would using PS cause any compatibility issues with streaming, at the server or at the listening end?

Actually I still don't understand the concept.
1. there is a server (icecast) that serves a stream to multiple listeners
2. there is a streamer (oddcast) that provides the server with the stream.

now what does the streamer do? Does it just read my pre-encoded aacplus, aacplus v2, etc files? Or does it encode stuff on the fly? (But encoding in aacplus is pretty slow, can it really do it on the fly?)

You're not supposed to change the sampling rate.

All of di.fm and sky.fm's HE-AAC streams are HE-AACv2 (SBR+PS).

If a decoder doesn't support PS, then it just won't sound as good.

Ok... I've spend enough time searching for a free aacplus streamer for freebsd and found none. Now I'm considering Vorbis. The question is, at 24 kbps, would Vorbis sound nearly as good as HE AAC PS?

Go to page http://www.shoutcast.com/#news and I'm sure that you will find free Shoutcat server able to stream AAC+ on any platform.

digitalsky: not even close. Vorbis is inferior until you start reaching about 80kbps.

And what do you mean by "streamer" exactly? If you mean the server that broadcasts, Icecast can do that just fine. If you mean something for encoding HE-AAC, then I have no idea.