PDA

View Full Version : FM>HiFi VCR>VHS>WAV>EAC>FLAC but is it lossy?


taygan
2006-01-16, 05:09 PM
I'm appreciating the dedication to good sources here, I've run into a lot of torrents that are not what they seem at 'other' sites.

Supposedly FM>HiFi VCR>VHS>WAV>EAC>FLAC It looks awfully blocky to me, but the blocks are before the analog generation, any ideas on how this happened?

The blocks look like they could be MD, but where? could a VCR do this? sat radio? hmmm...

imageshack.us is not working at the moment, I've attached the spec and freq.

Here's an 8 sec sample of the area analyzed.

http://s5.yousendit.com/d.aspx?id=09MHR3OHZCWQ326TXWXF8VC0LU

Thanks,

taygan

Five
2006-01-18, 01:47 PM
I am thinking the same thing you are, it is certainly lossy and the shape looks MD. I'm pretty sure a VCR couldn't do this. you can also see the mirroring from a bad upsample job.

http://img469.imageshack.us/img469/206/louiseattaqueblacksession11od.th.gif (http://img469.imageshack.us/my.php?image=louiseattaqueblacksession11od.gif)

range_hood
2006-01-19, 04:16 AM
Could this be a satelliteFM capture? There's no carrier visible.

lastepic
2006-01-21, 06:41 PM
Satellite isn't FM. it's broadcasted in MPEG 1 Layer II.

FM in itself is compressed, so that could be causing it-there is nothing else in that libneage that would make it 'lossy'

Five
2006-01-22, 12:16 PM
I see some very cubic shapes in the SA

this sure doesn't look like a normal FM

I'm also wondering how/when it could have been resampled to cause the mirroring artifacts

ssamadhi97
2006-01-23, 08:21 AM
Hmm, very odd one. Let me summarize what we're seeing so far (from my point of view ;))

FM
...somewhere around here, the following things must've happened:
1) lossy compression (from the looks of it I'd guess mp2)
2) resampling from 32 to 44.1kHz
In this order, too.

>HiFi VCR>VHS
...apparently caused lots of analog noise, which is fully preserved, so I'd say it's highly unlikely that any kind of lossy compression happened after this step

>WAV>EAC>FLAC
...yep, looks plausible to me when looking at the spectrum.


OK... now wtf? (where does the resampling come from?)

taygan
2006-01-29, 11:34 AM
Hmm, very odd one. Let me summarize what we're seeing so far (from my point of view ;))

FM
...somewhere around here, the following things must've happened:
1) lossy compression (from the looks of it I'd guess mp2)
2) resampling from 32 to 44.1kHz
In this order, too.


I'm not familiar with what mp2 looks like. the blocks look like MD to me, I assume mp2 is similar?

Maybe recorded on MD, or digital video camera at the show before FM broadcast?

I don't think that explains the resampling though.

taygan

ssamadhi97
2006-01-31, 12:46 PM
Compared to md-sourced recordings, mp2 (an audio format commonly used in digital radio and tv broadcasts) generally doesn't exhibit those little spikes around the blocks.. eh, the difference is kinda hard to describe.

One thing most mp2 and atrac (md) encoders seem to have in common is relatively aggressive lowpassing even below 16kHz, so the skyline-ish features of the spectrum are often more pronounced with these, compared to mp3s.