Music stream recording and format conversion(HowTo minimize downgrading of the audio)

[Iggy64]

I have some fundamental questions concerning audio stream recording.

Recording:
Most of the internet radio I enjoy streams mp3 at 128 kbps. I capture the streams using the StreamRipper plugin for Winamp. I assume that Streamripper is simply saving the mp3 as sent by the broadcaster; it is not converting from mp3 to something else, and then back to mp3. Is that a correct assumption?

Another option is to use something like Audacity to capture streams. The problem I see with this is that Audacity captures the stream from the sound card as its own proprietary .aup file. That is, it first decodes the mp3, then saves it as an aup file. To produce a playable mp3, I have to re-encode to mp3. I have always been taught to do the least possible amount of decoding and re-encoding, to minimize downgrading of the audio.

Splitting/Trimming:
If Streamripper is unable to cut the stream into individual mp3s (non-Shoutcast stream, for example), I use a direct mp3 editor, because that lets me trim the mp3s without converting decoding and recoding. Again, I presume this introduces the least corruption of the mp3.

Do I have all/any of this straight? Do some recorders capture the streamed mp3 directly, while others actually decode and re-encode? And do the latter type of recorders degrade the audio through those extra manipulations?

Direct sound recording software like Audacity and Replay Music records from your sound card. You can record anything with it, but you lose some quality when re-encoding audio.

Streaming audio/video rippers and streaming audio rippers like StreamRipper save the exact stream that is broadcasted onto your harddrive, so you don't lose any quality while using them.

So there are to types of programs that you can use, but sometimes it is really hard to find out from software description to which type it belongs.


I don't really know the proprietory format that Audacity uses, but most probably it is lossless, so actually you lose some quality when converting these files to MP3s. Of course you can use some lossless audio codec like FLAC, but I don't really see any sense in that when recording 128 k radio stations.


To split MP3 files you can use freeware MP3DirectCut. It does lossless splitting, so you won't lose any quality with it.

[Iggy64]

Thanks for the feedback, Stream Recorder.

I think for the most part, you are confirming what I suspected. I am using
StreamRipper for recording and MP3DirectCut for trimming, for the very reasons you mentioned.

It seems reasonable to me that decoding an mp3 stream and then re-encoding it is going to degrade the audio, which you don't want to do when your starting point is already as weak as 128kbps.

Even if the Audacity .auf format is lossless, it is still doing no better than capturing all the information in the streamed mp3. And in order to play the file captured by Audacity, I could code it to FLAC or APE to make it playable on most players, as you suggested. I wonder how the file size would turn out. I might have to try this just to see. In any case, I don't think I want to recompress back to an mp3, since that would no doubt degrade the audio relative to the original mp3.

Thanks, again, for helping me out.

Originally Posted by Iggy64

Even if the Audacity .auf format is lossless, it is still doing no better than capturing all the information in the streamed mp3. And in order to play the file captured by Audacity, I could code it to FLAC or APE to make it playable on most players, as you suggested. I wonder how the file size would turn out. I might have to try this just to see. In any case, I don't think I want to recompress back to an mp3, since that would no doubt degrade the audio relative to the original mp3.

IMHO there is no sense to use lossless codecs when recording 128k radio streams. Your will get much larger files (probably 10-20 times larger than 128k MP3s).

And it is very subjective whether the quality will degrade that much when re-encoding to MP3. IMHO it is OK to re-encode. Although I would prefer to use stream ripping software (especially when you can use some freeware software like StreamRipper).

And it is usually a good idea to re-encode MP3 to MP3, WMA to WMA, AAC to AAC,...

[Iggy64]

Thanks again, Stream Recorder.

I have, in fact, been using the StreamRipper plugin to capture Shoutcast streams through Winamp. It works very well, and allows me to listen to some great tracks that I missed, on a delayed basis -- just like using my DVR for TV.

What I'm trying to learn now is what to do with non-Shoutcast streams. I suppose I can also use Streamripper for those, too, and then cut the stream into more-manageable files using MP3DirectCut. I have some experimenting to to. As you can tell, I am pretty new to all this, and have much to learn.

Thanks again for your suggestions.

In many cases it is a good idea to analyze the stream format and protocol using freeware URL Snooper.

You can use lots of programs for non-shoutcast streams. If you have a list of formats (or at least web-sites) that you wanna record, we can suggest you software to use.

If you wanna record music from any radio station, you may use Replay Music. Although it records from your sound card, it can split and tag songs automatically.