| Author |
Message |
Jon Harris
Guest
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 Posted:
Tue Dec 13, 2005 9:15 am Post subject:
Re: Audio Compressor/AGC in C or C++ |
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<robert.w.adams@verizon.net> wrote in message
news:1134264573.722591.286330@g47g2000cwa.googlegroups.com...
| Quote: | I have done lots of digital compressors. RMS detection is a good way to
go because of the following;
RMS detectors have strange transient behavior because they look like a
1st-order lowpass filter fed by the square of the input signal. That
means the attack time-constant is dependant on the size of the
amplitude step you are making, since it gets squared before being
applied to the filter. But there is a workable compromise for the time
constant that is fast enough for most normal applications, without
causing too much distortion on steady sine-waves (RMS detectors produce
a ripple on their outputs at 2X the input frequency, causing
3rd-harmonic distortion).
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Bob, would you mind elaborating on that a bit, i.e. the time constant compromise
stuff? |
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Richard Owlett
Guest
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| Posted:
Wed Dec 14, 2005 1:16 am Post subject:
Re: Audio Compressor/AGC in C or C++ |
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Jon Harris wrote:
| Quote: | "Vladimir Vassilevsky" <antispam_bogus@hotmail.com> wrote in message
news:ICEmf.35582$Zv5.15048@newssvr25.news.prodigy.net...
Jerry Avins wrote:
I wish car radios had compressors so I could ride over road noise with open
windows without blasting myself on louder passages. It's not a great way to
listen to music, but it's better than not listening.
...The FM broadcast is usually heavily compressed too.
Almost always true for pop music stations, but much less so for classical
stations.
|
I once was a studio engineer for a student operated full commercial
license FM station that was a member of the QXR network (rebroadcasting
WQXR out of NYC).
You would have been drawn, quartered, salted, boiled in oil and *THEN*
tortured for even thinking compressors etc ;! |
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Jerry Avins
Guest
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| Posted:
Wed Dec 14, 2005 1:16 am Post subject:
Re: Audio Compressor/AGC in C or C++ |
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Richard Owlet wrote:
| Quote: | Jon Harris wrote:
"Vladimir Vassilevsky" <antispam_bogus@hotmail.com> wrote in message
news:ICEmf.35582$Zv5.15048@newssvr25.news.prodigy.net...
Jerry Avins wrote:
I wish car radios had compressors so I could ride over road noise
with open windows without blasting myself on louder passages. It's
not a great way to listen to music, but it's better than not listening.
...The FM broadcast is usually heavily compressed too.
Almost always true for pop music stations, but much less so for
classical stations.
I once was a studio engineer for a student operated full commercial
license FM station that was a member of the QXR network (rebroadcasting
WQXR out of NYC).
You would have been drawn, quartered, salted, boiled in oil and *THEN*
tortured for even thinking compressors etc ;!
|
Not at the transmitter, but in the (car) receiver. Or did you miss that?
Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ |
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Jon Harris
Guest
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| Posted:
Wed Dec 14, 2005 9:16 am Post subject:
Re: Audio Compressor/AGC in C or C++ |
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"Richard Owlett" <rowlett@atlascomm.net> wrote in message
news:11pucfacghtsa88@corp.supernews.com...
| Quote: | Jon Harris wrote:
"Vladimir Vassilevsky" <antispam_bogus@hotmail.com> wrote in message
news:ICEmf.35582$Zv5.15048@newssvr25.news.prodigy.net...
Jerry Avins wrote:
I wish car radios had compressors so I could ride over road noise with open
windows without blasting myself on louder passages. It's not a great way to
listen to music, but it's better than not listening.
...The FM broadcast is usually heavily compressed too.
Almost always true for pop music stations, but much less so for classical
stations.
I once was a studio engineer for a student operated full commercial license FM
station that was a member of the QXR network (rebroadcasting WQXR out of NYC).
You would have been drawn, quartered, salted, boiled in oil and *THEN*
tortured for even thinking compressors etc ;!
|
OK, but since you were just re-broadcasting other content, it would presumably
already have been squeezed where it originated.
Nowadays, many stations use a "broadcast processor", which is basically a
multi-band (like 5) compressor, plus other bells and whistles to squeeze the
heck out of the audio. Examples can be found at http://www.orban.com/ and
http://www.omniaaudio.com/. |
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Richard Owlett
Guest
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| Posted:
Thu Dec 15, 2005 5:16 pm Post subject:
Re: Audio Compressor/AGC in C or C++ |
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Jerry Avins wrote:
| Quote: | Richard Owlet wrote:
Jon Harris wrote:
"Vladimir Vassilevsky" <antispam_bogus@hotmail.com> wrote in message
news:ICEmf.35582$Zv5.15048@newssvr25.news.prodigy.net...
Jerry Avins wrote:
I wish car radios had compressors so I could ride over road noise
with open windows without blasting myself on louder passages. It's
not a great way to listen to music, but it's better than not
listening.
...The FM broadcast is usually heavily compressed too.
Almost always true for pop music stations, but much less so for
classical stations.
I once was a studio engineer for a student operated full commercial
license FM station that was a member of the QXR network
(rebroadcasting WQXR out of NYC).
You would have been drawn, quartered, salted, boiled in oil and *THEN*
tortured for even thinking compressors etc ;!
Not at the transmitter, but in the (car) receiver. Or did you miss that?
Jerry
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yes |
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