View Single Post
Old 30th January 2015, 10:08   #4
jaromanda
Forum King
 
Join Date: Jun 2007
Location: Under the bridge
Posts: 2,290
Quote:
Originally Posted by neralex View Post
If you are streaming with 128kbit then can encode the mp3 files directly to 128kbit. There is no reason to rip it with 320kbit and let the DNS encode the mp3 to a lower bitrate. In a perfect world should have the source the same bitrate as the stream.
DNS (you probably meant DNAS) doesn't do any encoding.

In the case of shoutcast toolset for broadcasting, it's the shoutcast DSP that encodes the stream ... which it does regardless of the source format .... i.e. if your file is 128kbit mp3 and your stream is 128kbit mp3, shoutcast DSP still encodes it

This is because shoutcast DSP receives the DECODED data (eg 16bit stereo PCM at 44,100Hz sample rate) - winamp sends this data to the DSP before it then sends it to the output plugin that is in use

a really simplistic view of the winamp "pipeline":

code:
input plugin (decodes the file) -> winamp -> DSP (encodes the file) -> winamp -> output plugin


technically, the DSP could alter audio, so it sounds different ... after all DSP stands for Digital Signal Processor - in broadcasting situation, as far as winamp is concerned, the DSP is doing nothing, as the data is unchanged by it.

in the shoutcast world, all source clients (shoutcast DSP, altacast, liquidsoap) behave the same way, source audio is always somehow decoded, the source client (shoutast DSP, altacast, liquidsoap etc) encodes this raw audio and sends it to DNAS, which distributes the data to the listeners unchanged (at least the audio part)

For this reason, it's best to have the source audio in the BEST quality you can manage (lossless is king) - because it will get decoded then re-encoded.

also, having the files in 320kbit means you can use them for other purposes that you may want higher quality for, as well as streaming

edit: this is much longer than what I was going to originally write, which was "magic elves do things for you" - but I couldn't let the misinformation go through to the keeper

"If you don't like DNAS, write your own damn system"

So I did
jaromanda is offline   Reply With Quote