- From: lonce <lonce.wyse@zwhome.org>
- Date: Fri, 14 Jun 2013 15:41:35 +0800
- To: public-webrtc@w3.org
- Message-ID: <51BAC92F.6020604@zwhome.org>
Hello -
I have a couple of questions I have not been able to answer myself
after looking over published docs. I am interested in maximum speed and
uncompromised quality transmission (for musical purposes), which leads
to these questions:
1) What exactly is the strategy of the "components to conceal packet
loss". Is there a strategy specifically for audio packet loss?
2) Can the audio echo cancellation (AEC), automatic gain control (AGC),
and noise reduction, be turned off (not used)?
3) Can compression by turned off completely (to avoid the algorithmic
delay of coding/endcoding)?
4) If you cannot bypass the compression algorithm, what is the minimum
delay one can achieve? It appears to me (from
http://www.webrtc.org/reference/architecture and
http://en.wikipedia.org/wiki/Opus_%28codec%29 ) that analysis frame
sizes down to 2.5ms (CELT layer) and 10ms (SILK layer) are possible.
This, in addition to "look ahead" and algorithm delay puts the minimum
delay at at least 20 ms, right?
5) Does one have control over how many analysis frames are sent per
packet (could I set it to 1)?
Musicians have been using a system called JackTrip (CCRMA, Stanford
University) which suuports uncompressed transmission, and
sub-millisecond frames (and packet) size. To recover from UDP losses, it
sends redundant streams, and the receiver takes the first packet that
arrives with the time stamp it needs next to reconstruct the audio on
the receiver. My questions above are all about how close WebRTC can come
to achieving the same performance.
Thanks!
- lonce
Received on Friday, 14 June 2013 07:42:12 UTC