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Lossy or Lossless? Please use this forum to post spectral and frequency analysis posts about shows you have your doubts about.

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  #16  
Old 2005-07-24, 05:06 PM
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Re: Radio Two = mp2?

thanks for the link... what I really need to get is a sample of audio that is confirmed NICAM. The info in the link is based on technology from 1993 I'm wondering what is happening now in 2005 and who is broadcasting using it these days.

Back at STG there was much discussion about lossy sources. One of the topics that obviously had to come up is that FM broadcasts look a lot like mp3 because they cut off around 15kHz. The differences that can be spotted are the carrier ("red stripe") up high and the fact that the cutoff (aka "haircut" in SA) of an FM broadcast is uneven. Most importantly, while an FM broadcast looses a lot of dynamic response and high frequencies, that's about all. Mp3 actually digs in and finds pieces of audio to remove below the steep cutoff to further reduce the quality. Old FM is "lossy" in a sense, but not in the sense that mp3 and the like is lossy. When TTD was started there was much discussion about allowing webcasts and "best source" broadcasts from mp3-like sources and it was decided that we would keep STG's standard of not allowing them.

Listening to the rem show it sounds like an FM broadcast, with some slurring and reduction in dynamics but not quite like the familiar mp3 sound. Looking at it, the haircut is completely straight and the carrier isn't a stripe, it looks more like a strange chain for want of a better description. I also listened to the webcast and found it to be absolutely awful, especially compared to the DIME recording. I'm also not spotting the legolike squares punched in the lower frequencies that are characteristic of mp3-like lossy. So my thought now is to allow bbc broadcasts so long as they are of the same quality as the rem show. The show I mentioned at the beginning of this thread would also be allowed in that case, since it appears about the same and is from the BBC. Another show from the same seeder had a couple tracks with yet another signature and would have to be discussed further to be allowed either in whole or in part, but that's another discussion.

So thank you for opening my eyes, 4c. I'm just waiting on a couple more opinions from other members, especially ssamadhi97 before going ahead and opening the floodgates so to speak.
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  #17  
Old 2005-07-24, 07:53 PM
4candles 4candles is offline
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Re: Radio Two = mp2?

Quote:
Originally Posted by Five
thanks for the link... what I really need to get is a sample of audio that is confirmed NICAM. The info in the link is based on technology from 1993 I'm wondering what is happening now in 2005 and who is broadcasting using it these days.
NICAM is used to provide digital stereo sound with analogue TV broadcasts in the UK. So any stereo recording from UK TV before about 2001 (i.e. before digital TV with MP2 audio became popular) will be NICAM sourced.

Quote:
Back at STG there was much discussion about lossy sources. One of the topics that obviously had to come up is that FM broadcasts look a lot like mp3 because they cut off around 15kHz. The differences that can be spotted are the carrier ("red stripe") up high and the fact that the cutoff (aka "haircut" in SA) of an FM broadcast is uneven. Most importantly, while an FM broadcast looses a lot of dynamic response and high frequencies, that's about all. Mp3 actually digs in and finds pieces of audio to remove below the steep cutoff to further reduce the quality. Old FM is "lossy" in a sense, but not in the sense that mp3 and the like is lossy. When TTD was started there was much discussion about allowing webcasts and "best source" broadcasts from mp3-like sources and it was decided that we would keep STG's standard of not allowing them.
You forgot to mention the heightened noise floor and the dynamic range compression applied by the broadcaster. DRC is generally not used on digital radio.

I'm always in two minds about TTD's "no digital broadcasts" policy. I seed a lot of "original bitstream" MP2 radio recordings at dimeadozen, but I don't seed them if I see that an FM recording is available. So on one hand, I agree that FM sources can be better, but I disagree with banning digital sources outright, because I think they are more than "good enough" if nothing better exists.

A digital broadcast is the equivalent of a broadcaster giving me (for example) a 192kbps MP2 copy of the master tape. This obviously isn't as good as a FLAC copy of the master tape, but IMO it isn't bad enough to be thrown away.

TTD seems to me to be very US-centric (for example, there are almost no PAL DVD torrents apart from my recent Live8 recordings), which probably explains why there is no demand for digital radio recordings - analogue radio still seems to be the norm in the US, apart from the subscription-based digital satellite services, which seem to have a poor reputation for audio quality.

But radio in Europe is very different, which I think explains Dime's more tolerant attitude towards digital broadcasts (Dime seems more Euro-centric). There are 1000s of free digital radio stations in Europe (and almost no subscription stations), and a digital-only future seems to be very close.

There are still some FM tapers (as the REM broadcast showed), but the number seems to be very small, and I would be surprised if it increased.

Going back to the subject of this thread, I don't think it is possible any more to generalise about FM radio - as your various examples are showing, there is a large variation in quality and "lossiness", even with the same radio station. So all you can probably do is to take each torrent as it comes.

At least with digital radio, you know exactly what you're getting, and tapers can easily make a "lossless recording" of the original compressed bitstream, thereby avoiding any more loss in audio quality.
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  #18  
Old 2005-07-24, 07:55 PM
deadave deadave is offline
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Re: Radio Two = mp2?

Is it maybe from here?
http://www.rawlinsonend.co.uk/
click on noises then radio 2 documentary
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  #19  
Old 2005-07-24, 10:21 PM
bellestar827
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Re: Radio Two = mp2?

Here are some more BBC radio sourced tracks, these are from broadcasts of the 2002 Cambridge Folk Festival. The stated lineage is:
BBC FM > hi-fi CDR > WAV > Wavelablite for edits > FLAC

Not sure if these are from Radio Two or not, but I think they probably are.
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File Type: jpg ZoomedSpectral.jpg
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File Type: jpg Spectral.jpg
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File Type: jpg Frequency.jpg
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  #20  
Old 2005-07-24, 10:25 PM
bellestar827
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Re: Radio Two = mp2?

From a different Cambridge track:
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File Type: jpg ZoomedSpectral2.jpg
( 534.1 KB, 10 views)
 
File Type: jpg Spectral2.jpg
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File Type: jpg Frequency2.jpg
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  #21  
Old 2005-07-25, 05:21 AM
4candles 4candles is offline
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Re: Radio Two = mp2?

If anyone is interested in a pure MP2 broadcast, I've uploaded a 30-second sample from Radio Two here:

FLAC format (yousendit.com - expires 1 Aug 2005)

Original MP2 data (yousendit.com - expires 1 Aug 2005)

It's an acoustic radio session (I think it was live) from April 2005 recorded from the digital satellite version of Radio Two using a PC receiver card to capture the original compressed bitstream.

The FLAC version was created by first converting the MP2 file to WAV using "madplay" (the example player that comes with libmad) and then using "flac -8" to convert to FLAC. I left it at the original 48KHz samplerate.
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  #22  
Old 2005-07-25, 05:29 AM
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Re: Radio Two = mp2?

thanks guys for all the responses... I need to take a bit of time to put it all together and a big work week is starting for me today.

btw deadave, that mp3 you linked is the same show as that "Big Shot. The Vivian Stanshall Story" but the quality is much lower than the torrent I took screenshots from at the beginning of the thread.
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  #23  
Old 2005-07-25, 06:09 AM
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Evenreven Evenreven is offline
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Re: Radio Two = mp2?

Quote:
Originally Posted by Five
Evenreven, this holds true at most other sites but at TTD lossy sources aren't tolerated no matter how they came to be with only two exceptions: 1) AC3 on a DVD. We prefer WAV audio of course but will accept AC3. If the AC3 is ripped from the DVD it is not allowed to be seeded separately in the audio section. 2) MiniDisc, only when it is the master recorded at the show either sbd/aud/mtx. MD is not allowed to be used to tape broadcasts and also isn't allowed midway thru the lineage.

So the main thrust of this thread is to ask the question is everything coming from the BBC lossy except WWO preFM discs and the like? From what I see here it looks like not only the satellite broadcasts but also the traditional "over the air" broadcasts are lossifiedized at the station and that's a real drag 'cause everyone loves the beeb's content.
I don't get it, Five... My point was: if you tape something from analogue FM radio and the signal at no point whatsoever was lossy (i.e. in the pre-programme chain at the Beeb), then what would the problem be? Other than that cassette is a rather lo-fi format, of course. How would it be digitally lossy?

And I know the AC3 and MD master thingies. But it can't be pointed out often enough, I guess.
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  #24  
Old 2005-07-25, 08:58 PM
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Re: Radio Two = mp2?

Quote:
Originally Posted by Evenreven
I don't get it, Five... My point was: if you tape something from analogue FM radio and the signal at no point whatsoever was lossy (i.e. in the pre-programme chain at the Beeb), then what would the problem be? Other than that cassette is a rather lo-fi format, of course. How would it be digitally lossy?

And I know the AC3 and MD master thingies. But it can't be pointed out often enough, I guess.
no problem whatsoever if that's the case... I'll post something a little more clear here when I find a couple hours in the next couple days.

My original question was asking if the analogue FM signal at the beeb is sourced from lossy or not and it's looking like the answer I'll find is "hell, no!"
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  #25  
Old 2005-07-29, 03:05 PM
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Re: Radio Two = mp2?

Quote:
Originally Posted by bellestar827
Here are some more BBC radio sourced tracks, these are from broadcasts of the 2002 Cambridge Folk Festival. The stated lineage is:
BBC FM > hi-fi CDR > WAV > Wavelablite for edits > FLAC

Not sure if these are from Radio Two or not, but I think they probably are.
okay, this first track you posted shots of is no good... looks like MD which is cool if it is taped at the venue but not in the middle of the lineage. MD isn't even listed in the lineage. This is certainly lossy and not because of the station it was done afterwards (no carrier visible, legoland skyline).

the 2nd track resembles the bbc broadcast stuff and is good for sharing. check all the tracks and try to contact the seeder.

sorry to leave it hanging, work has been crazy... for TTD purposes if an FM looks like the rem screenshots or the screencaps from the second Cambridge track we consider them lossless and fine for trading (as does dime).
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