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Topic: Sat/DVB audio bitrate and frequency cutoff (Read 9118 times) previous topic - next topic
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Sat/DVB audio bitrate and frequency cutoff

Hello folks.

I have read in a few places that bitrate from Sat (Dishnet) on radio (Sirius) is 192kb/s and up.

Can anyone tell me if there is a way to check/test this myself with the equipment I have? I have receiver optical out fed into optical in on an M-Audio Transit USB.

I do notice that frequency seems to cut off at about 13Khz... any comments on this?


Thanks!

Sat/DVB audio bitrate and frequency cutoff

Reply #1 –
Sirius uses PAC, and XM uses CT's HE-AAC encoder. Considering PAC is designed for low bitrate-ish use, I would imagine that the bitrates are far lower than 192kbps.

Sat/DVB audio bitrate and frequency cutoff

Reply #2 –
Quote from: Firon on
Sirius uses PAC, and XM uses CT's HE-AAC encoder. Considering PAC is designed for low bitrate-ish use, I would imagine that the bitrates are far lower than 192kbps.


Thanks. There is supposed to be a big difference between standard broadcast and the ones that go through DishNet.

Anyway my question was how would I go about checking what the bitrate is myself?

Sat/DVB audio bitrate and frequency cutoff

Reply #3 –
I doubt the stream coming in through Dish Network is PAC (dishnet would have to include a decompressor for it on all their receivers).  It's probably coming in to Dish Network from Sirius and being compressed with whatever codec the sats use before going out.

Sat/DVB audio bitrate and frequency cutoff

Reply #4 –
Oh, my bad, I didn't read very well. Sirius's broadcast is using PAC, but I have no idea if they give Dish a different feed/codec. It'd make sense if they did, though.

Sat/DVB audio bitrate and frequency cutoff

Reply #5 –
Quote from: benski on
I doubt the stream coming in through Dish Network is PAC (dishnet would have to include a decompressor for it on all their receivers).  It's probably coming in to Dish Network from Sirius and being compressed with whatever codec the sats use before going out.



Yes I believe it is MP2 (or is that MPEG-II, I still confused about diff!) So I guess it is one/some of these but is there a way to tell? And does the 13khz - 14khz cutoff I can see suggest anything?

    * Sampling rates: 32, 44.1 and 48 kHz
    * Bitrates: 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 and 384 kbit/s

An extension has been provided in MPEG-2 Layer II and is defined in ISO/IEC 13818-3

    * Additional sampling rates: 16, 22.05 and 24 kHz
    * Additional bitrates: 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144 and 160 kbit/s

Sat/DVB audio bitrate and frequency cutoff

Reply #6 –
A 14khz lowpass sounds a lot like MP2 at 128kbps (possibly with intensity stereo).

Sat/DVB audio bitrate and frequency cutoff

Reply #7 –
Quote from: Firon on
A 14khz lowpass sounds a lot like MP2 at 128kbps (possibly with intensity stereo).



Thanks. Can you tell me how you deduct this/any way to know that it is not say 192?

Also is there any conceivable way to find out rather than hypothesize?

Sat/DVB audio bitrate and frequency cutoff

Reply #8 –
Encode something yourself with Twolame at 128kbps and 192kbps and see what the lowpass is.

Edit: oops. That was the lowpass with a 32000Hz sample rate.

Twolame uses an 18~19KHz lowpass at 192kbps. Even using PAM 0 (the worst psychoacoustic model in Twolame), it's still 15-16KHz. Of course, the MP2 encoders that DAB broadcasters are using might behave differently...

Sat/DVB audio bitrate and frequency cutoff

Reply #9 –
Thanks. You so smart!

Please excuse my absolute newbieness. If you look at this image, would I get anything out of trying to increase > 13Khz?

Sat/DVB audio bitrate and frequency cutoff

Reply #10 –
This topic shouold better probbaly in sub-forum "other adio codecs", but never mind.
IIRC, I wrote already something in "other audio codecs forum" about Sat/DVB-S (digital video broadcasting - satellite), and howto record radio and getting the audio (or video).

edit:

http://www.hydrogenaudio.org/forums/index....hl=pvastrumento        <-- forum search for pvastrumento was successful
here you find also my findings for frequency cutoffs.

You record the stream,
then you need to demux (demultiplex) audio n video by PVAstrumento ,
cutting (removing advertismeents eg.) by Cuttermaran
authoring DVD (eg. multplxing = muxing video n audio together again) by dvdauthor-gui.
At least, in Germany/Europe, Astra, hotbird satellties, you have mpeg2 for video n audio, which means infact mp2 for th audio.
iirc, if you record radio from dvb-s , you need only the step by PVAstrumento , as there is no video, if you don#t need the cutting.
the raw radio streams renamed to mp2 didn#t play well in foobar, aftr running them through pvastrumento, those mp2 played fine.

I recall, i described it exactly in that topic of mine in the otehr forum.

mostly, 192k mp2 is used, soemtimes 224 or 256k mp2 by better quality stations.

Sat/DVB audio bitrate and frequency cutoff

Reply #11 –
Hey user great timing and interesting read.

My decent CD player recently died and I play CD through DVD player. I wandered how it is that dish +sir sounds so sweet to me preferring the sound over the DVD player.

Then I see cutoff around 13K and thinking hmm I must not be much of an audiophile if that sounds good to me.

For recording all I am doing is going from receiver's optical out into optical in on M-Audio card 16bit/44k..... again excuse my newbiesness but are you suggesting that there are problems with this?



Thanks!







Quote from: user on
This topic shouold better probbaly in sub-forum "other adio codecs", but never mind.
IIRC, I wrote already something in "other audio codecs forum" about Sat/DVB-S (digital video broadcasting - satellite), and howto record radio and getting the audio (or video).

edit:

http://www.hydrogenaudio.org/forums/index....hl=pvastrumento        <-- forum search for pvastrumento was successful
here you find also my findings for frequency cutoffs.

You record the stream,
then you need to demux (demultiplex) audio n video by PVAstrumento ,
cutting (removing advertismeents eg.) by Cuttermaran
authoring DVD (eg. multplxing = muxing video n audio together again) by dvdauthor-gui.
At least, in Germany/Europe, Astra, hotbird satellties, you have mpeg2 for video n audio, which means infact mp2 for th audio.
iirc, if you record radio from dvb-s , you need only the step by PVAstrumento , as there is no video, if you don#t need the cutting.
the raw radio streams renamed to mp2 didn#t play well in foobar, aftr running them through pvastrumento, those mp2 played fine.

I recall, i described it exactly in that topic of mine in the otehr forum.

mostly, 192k mp2 is used, soemtimes 224 or 256k mp2 by better quality stations.

Sat/DVB audio bitrate and frequency cutoff

Reply #12 –
Quote from: nonsub on
For recording all I am doing is going from receiver's optical out into optical in on M-Audio card 16bit/44k..... there are problems with this?
Thanks!


hm, specifying 16/44.1 doesn#t make sense while recording, probably it comes out of sat receiver as 48 kHz.

And furthermore, I would record it directly as mp2 by PC-Sat-card/usb-sat-pc-device, not as uncompressed wave through soundcard (as you rely then on the decoding of the receiver, and you get uncompressed stuff, which would suffer again by 2nd !! encoding to some lossy, while the directly recorded mp2 is compressed fine, and you don't get better quality for that size out of sat, especially not by recording from the digital-out of the receiver.)

Sat/DVB audio bitrate and frequency cutoff

Reply #13 –
hoi there

im also interested in some technical details about satellite radio in the U.S. and A, especially XM The Move.
As already mentioned above, XM uses the CT's HE-AAC encoder.
Since im from germany, i dont have the chance to test it for myself so my simple question is:
What settings would be recommended to transcode the XM The Move to a mp3?
Are more than 192kbps necessary? can it be said in general regarding to the signal of XM Radio what settings are the
smartest?

im looking forward for your replies