Audio codecs and quality on sat-programms

[Satphoenix]

Hello,

I've a question as a new digital sat user. What codecs and quality for audio streams and digital radios are used by sat-transmissions?

I hope this question is not to complicated.

Greets

[marian321]

Re: Audio codecs and quality on sat-programms

There a at the moment 2 different codecs in use, mp2 and ac3 (dolby digital). The quality depends an the bitrate of the stream. Often used are 128kbits up to 320kbits in mp2 and 384kbits to 448kbs in ac3.

[digicon]

Re: Audio codecs and quality on sat-programms

Most prominently used now as stated above is AC3 in both 5.1 and 2 channel broadcast at 192khz, more and more channels are switching from MPEG2 audio to AC3 to save on bandwidth for said channels

[herrr]

Re: Audio codecs and quality on sat-programms

Most prominently used now as stated above is AC3 in both 5.1 and 2 channel broadcast at 192khz, more and more channels are switching from MPEG2 audio to AC3 to save on bandwidth for said channels

It's not so easy to switch standard from one day to another...leaving people with old receivers with dumb TVs...
AC3 usually goes with DVB-S2, or (such as Arte on Hotbird) together with MPEG4 video...and as a matter of fact that switch was not a good surprise for a lot of people.
On HD terrestrial TV with standard DVB-T video is HD, but AUDIO STILL mp2!!!!
Old TVs and decoders can only listen and not watch: that's to say that nobody is in a hurry to switch to AC3...

[marian321]

Re: Audio codecs and quality on sat-programms

The quality you asked for depends on the bitrate. 192kbit mp2 (which most providers use) are equal to 128kbit mp3.
They use still mp2 because it's definied in the dvb standard so that all receivers (sd or hd) "understand" it. But thats an advantage if you want to stream the signal and convert it to dvd. For most Televisions even 128kbits mp2 are enough but if you prefer surround sound thats not enough. Then you should prefer the ac3 stream.

[Satphoenix]

Re: Audio codecs and quality on sat-programms

Thanks for the answers.

Are there differences in quality between mp2 and ac3 even when they use same bitrate?

[marian321]

Re: Audio codecs and quality on sat-programms

Ohh yes, there are differences. AC3 uses better codec-algorythms and can be compared in quality with mp3. But with 384kbits ac3 you have to divide it to 6 seperated channels (5 normal and 1 subwoofer) so that for every channel there is only 64kbits. but with a good sound system you get an impressive result.
E. g. in normal cinemas there are normaly used 320kbits with ac3.

[herrr]

Re: Audio codecs and quality on sat-programms

Thanks for the answers.

Are there differences in quality between mp2 and ac3 even when they use bitrate?

Do you mean THE SAME bitrate?
Yes, because AC3 is more efficient and with the same bitrate allows better quality.
If you mean with different bitrate...is a question not so scientific...we can find perhaps some situations with similar quality.

Edit: sorry...marian is always quicker...and perhaps his answers are better.
But remains the doubt about the meaning of question...

[Fireflyer]

Re: Audio codecs and quality on sat-programms

There a at the moment 2 different codecs in use, mp2 and ac3 (dolby digital). The quality depends an the bitrate of the stream. Often used are 128kbits up to 320kbits in mp2 and 384kbits to 448kbs in ac3.

Have there been other audio codecs used in dvb-s as mp2 and ac3?

[marian321]

Re: Audio codecs and quality on sat-programms

Yes, a view years ago there were transmissions in dts (digital theatre system) at 4,8° east or 1° west, but that uses a lot of capacity with 768 kbits. I don’t have this sats so I have no Idea if they still do this. Perhaps lyngsat gives the answer. But I think mp2 and ac3 are the only used codecs at the moment on all sats.

[Fireflyer]

Re: Audio codecs and quality on sat-programms

How many kbits are necesarry in mp2 or ac3 to reach cd-quality? It is always told that digital sound on sat has a very high quality.

[marian321]

Re: Audio codecs and quality on sat-programms

Ohh, thats sometimes a difficult question.
With mp2 stereo my experience are ~300 kbits. In ac3 stereo you get the same result with 192kbits. Thats equal to 192kbits mp3, which is very near to cd-quality.
On 19,2° east many radio station use 320kbits mp2. This gives a very good sound performance.
Perhaps other users have other or same experience?