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ashjmckenzie  
#1 Posted : Tuesday, November 5, 2019 4:31:56 AM(UTC)
ashjmckenzie

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Testing VMIX SRT to VMIX SRT over the weekend, Worked very well, much better than older Teradeks

50i Decklink SDI > 1080 50p VMIX Encode > SRT 720 50p 2.5mbit > 1080 50p VMIX Decode > 50i Decklink SDI

The Motion looked amazing, looked like interlaced content :)

I was on 23.0.0.21 HEVC Looked Noticely worse than H264
I've since upgraded to 23.0.0.22 and HEVC looks to be better

The Audio Encoder is defiantly not working properly

I was transmitting 4 Channels of audio,
is the audio bitrate shared with all 4 channels??

64kpbs sounds like 32kbps
128 sounds like 64kbps
256 sounds like 128kbps

I have test wavs at 64, 128, 256, 384

Can we get more control of the SRT encoder, ABR and VBR options
In addition TCP/WEB API control of the entire SRT encoder options
MartLeib  
#2 Posted : Tuesday, November 5, 2019 8:08:11 AM(UTC)
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Audio bitrate is shared. You can just use 512Kbps to achieve 128Kbps per stereo pair when streaming all 8 channels.
thanks 1 user thanked MartLeib for this useful post.
ashjmckenzie on 11/5/2019(UTC)
ashjmckenzie  
#3 Posted : Tuesday, November 5, 2019 8:13:34 AM(UTC)
ashjmckenzie

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Originally Posted by: MartLeib Go to Quoted Post
Audio bitrate is shared. You can just use 512Kbps to achieve 128Kbps per stereo pair when streaming all 8 channels.


This makes sense, many thanks
Paul_WCP  
#4 Posted : Sunday, December 15, 2019 8:49:23 PM(UTC)
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to add a question to this. Is there an upper limit for audio bitrate in SRT?
I am running tests with 8 Channel Audio and want them as HQ as possible.

It's pretty hard to tell right now what's the reason for the SRT connection not establishing.


Also: If I get this right I have BUS MABC as a stereo pair each. Are these Stereo Pairs somehow synched in SRT?
MartLeib  
#5 Posted : Sunday, December 15, 2019 11:04:18 PM(UTC)
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I do not know regarding the upper limit, but no point to go over 320Kbps per bus. Totaling in 320 x 4 = 1280Kbps.

Your SRT video output is synced to all the audio buses you are sending.
Paul_WCP  
#6 Posted : Monday, December 16, 2019 6:36:56 AM(UTC)
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Originally Posted by: MartLeib Go to Quoted Post
I do not know regarding the upper limit, but no point to go over 320Kbps per bus. Totaling in 320 x 4 = 1280Kbps.

Your SRT video output is synced to all the audio buses you are sending.


Are you sure about that? Video is not even that important to me, but I need sample exact sync on the audio buses because I want to send multitrack music.
My information is that even Haivision says in their Makitos there is no guaranteed sync between the audio channels.
ranz  
#7 Posted : Wednesday, March 25, 2020 11:00:56 PM(UTC)
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Originally Posted by: Paul_WCP Go to Quoted Post
Originally Posted by: MartLeib Go to Quoted Post
I do not know regarding the upper limit, but no point to go over 320Kbps per bus. Totaling in 320 x 4 = 1280Kbps.

Your SRT video output is synced to all the audio buses you are sending.


Are you sure about that? Video is not even that important to me, but I need sample exact sync on the audio buses because I want to send multitrack music.
My information is that even Haivision says in their Makitos there is no guaranteed sync between the audio channels.


I'm still searching for a high quality audio streaming setup where the video isn't as important as the audio. It seems to be always the other way around.

So if I understand this correctly - SRT really compresses the hell out of the audio? Is there any technical details on this anywhere?

What I would like is something like what Netflix use (on their audio side it's 640kbps) - or even non-compressed audio streaming raw. 48K + (prefer 96K) sample rates.

Video can be 720p for all I care ;)
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