Quality loss when broadcasting live through sc_trans2

centerm · 27th July 2013, 14:18

I'm using Shoutcast and sctrans to transmit into aacPlus, in case 32kbps. The audio sctrans is perfect, but when I connect (using the alternate port, not to stop the sctrans) audio broadcast live has a major loss of quality.
Is there any procedure that can be done to minimize this loss?

DrO · 27th July 2013, 14:58

there is going to be audio loss as you're likely transcoding something which has already been transcoded from the DJ source being used and transcoding something which is already transcoded will do that.

other than ensuring the DJ source is connected at as high a bitrate as needed for the stream(s) coming out of sc_trans to try to lessen the impact of throwing more audio data away, there's not too much you can do about it.

centerm · 27th July 2013, 16:01

Sorry for my English (translator - I'm brazilian)
What I realize is that there is no loss in audio quality in itself, but a part of the audio. Whenever I start to hear an audio aac, it starts to sound like it's mono sound, one second and then goes the rest of the audio (which gives the highest quality audio). It is this last part of the audio that seems to get lost when transmitting live using sctrans.
I could not quite understand what u mean by increasing the quality, as already tested in various qualities and always the sound loses this part "stereo"

DrO · 27th July 2013, 17:16

what I mean is the DJ source needs to be providing a higher bitrate than what you provide to the listeners e.g. 320kbps even if the output is going to be 32kbps.

centerm · 27th July 2013, 17:42

320kbps is high for Brazilian connections, but I'll try to test here.

DrO · 27th July 2013, 18:50

that was just an example. you'll probably need to try different inputs to see what works. also make sure you haven't changed any of the aac encoder settings in the sc_trans concig file ie you just left it use the built in defaults.

centerm · 27th July 2013, 19:02

Actually use the panel CentovaCast 3, have released a 500kbps limit for this test account and tried to connect with 320, but the server stop. I will compare the configuration file to see what might be happening. Thanks for the help.

Tested at 128 and 160kbps and the loss of quality is now almost imperceptible.
Thank you again.

27th July 2013, 14:18	#1
centerm Junior Member Join Date: Jul 2013 Posts: 7	Quality loss when broadcasting live through sc_trans2 I'm using Shoutcast and sctrans to transmit into aacPlus, in case 32kbps. The audio sctrans is perfect, but when I connect (using the alternate port, not to stop the sctrans) audio broadcast live has a major loss of quality. Is there any procedure that can be done to minimize this loss?

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27th July 2013, 14:58	#2
DrO Join Date: Sep 2003 Posts: 27,873	there is going to be audio loss as you're likely transcoding something which has already been transcoded from the DJ source being used and transcoding something which is already transcoded will do that. other than ensuring the DJ source is connected at as high a bitrate as needed for the stream(s) coming out of sc_trans to try to lessen the impact of throwing more audio data away, there's not too much you can do about it.

27th July 2013, 16:01	#3
centerm Junior Member Join Date: Jul 2013 Posts: 7	Sorry for my English (translator - I'm brazilian) What I realize is that there is no loss in audio quality in itself, but a part of the audio. Whenever I start to hear an audio aac, it starts to sound like it's mono sound, one second and then goes the rest of the audio (which gives the highest quality audio). It is this last part of the audio that seems to get lost when transmitting live using sctrans. I could not quite understand what u mean by increasing the quality, as already tested in various qualities and always the sound loses this part "stereo"

27th July 2013, 17:16	#4
DrO Join Date: Sep 2003 Posts: 27,873	what I mean is the DJ source needs to be providing a higher bitrate than what you provide to the listeners e.g. 320kbps even if the output is going to be 32kbps.

27th July 2013, 17:42	#5
centerm Junior Member Join Date: Jul 2013 Posts: 7	320kbps is high for Brazilian connections, but I'll try to test here.

27th July 2013, 18:50	#6
DrO Join Date: Sep 2003 Posts: 27,873	that was just an example. you'll probably need to try different inputs to see what works. also make sure you haven't changed any of the aac encoder settings in the sc_trans concig file ie you just left it use the built in defaults.

27th July 2013, 19:02	#7
centerm Junior Member Join Date: Jul 2013 Posts: 7	Actually use the panel CentovaCast 3, have released a 500kbps limit for this test account and tried to connect with 320, but the server stop. I will compare the configuration file to see what might be happening. Thanks for the help. Tested at 128 and 160kbps and the loss of quality is now almost imperceptible. Thank you again.