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Topic: Discontinuous transmission in AAC (Read 2021 times) previous topic - next topic
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Discontinuous transmission in AAC

Hello. Does AAC support discontinuous transmission?

Re: Discontinuous transmission in AAC

Reply #1 –
Why nobody answered this?

Re: Discontinuous transmission in AAC

Reply #3 –
@Case Yes, I mean that. Now I'm asking the same question with different words: Does AAC support very low bitrates (below 1kbps) for silent moments?

Re: Discontinuous transmission in AAC

Reply #4 –
It does. But you can also just stop transmitting the audio data.

Re: Discontinuous transmission in AAC

Reply #6 –
I'm not too sure if AAC or other codecs actually (could) support DTX. I'm only aware of Speex and AMR.
But even when possible, it isn't optimal by codec design. I mean, Opus maybe could handle that, but AAC, MP3 or Vorbis... I just don't know.

Re: Discontinuous transmission in AAC

Reply #7 –
You could view vbr as some form of DTX where the bitrate is always dependant on the complexity of the musical content.
I dont think that the codec just stops transmitting, when it detects silence, but i do know that when a flac files is encoded with very silent or close to no music it pretty much hits 0kbps. So i guess that means it still stays continuous with minimal bandwidth.

I am sure it is a similar story with aac vbr but i dont know how low the encoder goes. This should be easily testable though.
And so, with digital, computer was put into place, and all the IT that came with it.

Re: Discontinuous transmission in AAC

Reply #8 –
Quote from: Kartoffelbrei on
You could view vbr as some form of DTX where the bitrate is always dependant on the complexity of the musical content.

Not exactly. For example, MP3 can handle VBR but it does not go below 8kbps and 8kbps is a very high bitrate to be considered as DTX.

Re: Discontinuous transmission in AAC

Reply #9 –
Quote from: Klymins on
Quote from: Kartoffelbrei on
You could view vbr as some form of DTX where the bitrate is always dependant on the complexity of the musical content.

Not exactly. For example, MP3 can handle VBR but it does not go below 8kbps and 8kbps is a very high bitrate to be considered as DTX.

That's a good point, DTX is not the same as VBR.
AFAIK, DTX consists of transmitting no information packets (just a few bits per second) at times when "voice activity" is very low (silence or noise). This is, to save resources in processing and bandwidth, things that were scarce at the time when this technology was implemented (90's and early 2000's).