A question regarding the various "setMinMaxBitrate"

[neilyoung]

The upgrade statements says:

Since my code is still compatible to 6.18 I'm reflecting this like so:

                if (this.versionCompare(this.kmsVersion, '6.18.0') < 0) {
                    await webRtcEndpoint.setOutputBitrate(config.maxBandwidth * 1000)
                }
                else {
                    await webRtcEndpoint.setMinEncoderBitrate(config.maxBandwidth * 1000 / 10)
                    await webRtcEndpoint.setMaxEncoderBitrate(config.maxBandwidth * 1000)
                }

Branch passed here the "else" branch.

I'm now having a room setting config.maxBandwidth, which defines the bandwidth to be configured at several occasions in kBps. It is set to 3000 currently.

In a publisher-filter-subscriber scenario this now leads to a publisher stream of constant 3MBit/s, which is then treated by the filter (transcoded before the delivery to OpenCV) and re-encoded, same standard H.264.

In previous version 6.18. I was able to see, that - if no movement is in the publisher video - the subscriber's input bitrate was about 300kBps, which matches the setMinEncoderBitrate setting. And it did follow up to 3MBit/s,.

But regardless of how many changes I produce publisher side in KMS 7.0.0, these subscriber video bitrate never exceeds 1 MBit/s.

EDIT: And the video quality subscriber side is accordingly bad.
Why is that so?

[neilyoung]

If I config it in /etc/kurento/modules/kurento/MediaElement.conf.ini - perfect. 3M constant.

But this is a room setting, I would like to set it programmatically.

[neilyoung]

Confirmed. The programmatic setting of min/max encoder bitrate does not work :(

I swear, it worked in the compiled version I made last week from 7.0.0-dev. I was using setMin/MaxOutputBitrate that time, but these APIs are gone now.

EDIT: That being said I see a regression here.

EDIT2: I also double checked that I'm setting the proper values:

2023-03-23T17:32:48.772Z info: setEncoderBitrate 3000000 setMinEncoderBitrate 300000 setMaxEncoderBitrate 3000000

[j1elo]

This does look like a regression that I'll have to look into. The OutputBitrate properties had the issue that the average bitrate of the encoder was hardcoded to 300 kbps, and that gave weird results especially for people who used the API with a very low minimum, a very high maximum, and never saw the average bitrate grow above 300 Kbps (because, well, it was hardcoded that way).

So the EncoderBitrate API was added to be a replacement that works as expected. Namely:

If you set the minimum at e.g. 100 Kbps, the maximum at 10,000 Kbps, and the average target at 5,000 Kbps, you should see an average bitrate output of 5 Mbps which depending on the scene, might raise up to 10 Mbps or go as low as 100 Kbps (always according to the decisions made by the encoder).

If that's not the behavior you're seeing, then something is definitely wrong in there. Please try that instead of setting everything to the same value.

Another thing that might be happening is that the min/max collision detection has a bug and when setting everything to the same value, the code is becoming a bit crazy... I'll look at the logic behind this to see if there is anything suspicious.

[neilyoung]

Do I have to set these values as "kBps" or as "bps"?

[j1elo]

As "bps" - see JS docs at BaseRtpEndpoint.getEncoderBitrate

[neilyoung]

Yepp. But it doesn't change much. I can re-read my settings, so they arrive somewhere. But I can't see an effect.

Any hint, what I could trace in KMS in order to see more?

[neilyoung]

I tried "kbps" first.

Publisher side:

Subscriber side:

Setting:

2023-03-23T19:33:25.459Z info: setEncoderBitrate 5000 setMinEncoderBitrate 100 setMaxEncoderBitrate 10000

Verdict: Doesn't work

Will try "bps" next.

[neilyoung]

With "bps"

Publisher:

Subscriber:

Setting:

2023-03-23T19:37:41.374Z info: setEncoderBitrate 5000000 setMinEncoderBitrate 100000 setMaxEncoderBitrate 10000000

Verdict: I don't know. Seems to not work

[neilyoung]

I was wrong. It does also not work with the kms7-dev version I installed last week. Very weird...

[neilyoung]

Q: I suppose the kurento-client 7.0.0 (npm) is not backward compatible to a 6.18.0 KMS installation, right? Especially because of the fact, that setOutputBitrate is no longer available?

[neilyoung]

Hi Juan, is there any progress here? Any hint, what to examine?

[neilyoung]

I really wonder, what the problem is: The publisher pumps with constant 3M, but the subscriber (transcoding) is not getting significantly more that 500K.

Even though I'm reportedly setting everything right:

2023-03-27T10:45:01.828Z info: getEncoderBitrate 3000000, getMinEncoderBitrate 1500000, getMaxEncoderBitrate 4500000

Why does this not work? It works fine, if I set the variables in the *.ini.

[neilyoung]

It is definitely only working with static config:

For the API I'm now convinced, that there is a bug. For instance: The order of "setMin/Max" is deciding. If you set MIN before MAX you will get this warning:

2023-03-27T12:06:04,775792 25283 0x00007ffa93842700 warning kmselement kmselement.c:1294 kms_element_set_property() Ignoring requested bitrate min > max; setting max: 0

This is all so weird... Very disappointing....

[neilyoung]

Also a nice one:

2023-03-27T12:46:47,202074 33827 0x00007fbf7da5f700 warning kmselement                kmselement.c:1308 kms_element_set_property() <kmswebrtcendpoint4>  Ignoring requested bitrate max < min; setting min: 500000
2023-03-27T12:46:47,202933 33827 0x00007fbf7c25c700 warning kmselement                kmselement.c:1279 kms_element_set_property() <kmswebrtcendpoint4>  Ignoring out of bounds requested target bitrate; setting default: 300000

Or this:

2023-03-27T12:51:53,828216 36804 0x00007f55c9f46700 warning kmselement                kmselement.c:1279 kms_element_set_property() <kmswebrtcendpoint1>  Ignoring out of bounds requested target bitrate; setting default: 300000

on this sequence:

                    await webRtcEndpoint.setMaxEncoderBitrate(10000000)
                    await webRtcEndpoint.setMinEncoderBitrate(10000000)

                    await webRtcEndpoint.setEncoderBitrate(3000000)

Don't get it...

[neilyoung]

I think the only way out of this dilemma is to

a) drop all that more or less stupid validation
b) create a new setEncoderBitrates(min, max, target) API

[neilyoung]

OK, giving up here. This is entirely broken. Only fix configuration kind of works. "Kind of": It keeps the target bitrate, no min, no max. Any attempt to configure whatever bitrate later on (even with all verifications removed) does fail silently. Subscriber side this looks like so then (the received bitrate meanders around 300k, even all logs confirm the proper setup).

0:00:24.147464461 47087 0x7fe6b00022c0 DEBUG   KurentoMediaElementImpl MediaElementImpl.cpp:689:MediaElementImpl: Configured target video bitrate for media transcoding: 3000000 bps
0:00:24.147493000 47087 0x7fe6b00022c0 DEBUG   KurentoMediaElementImpl MediaElementImpl.cpp:694:MediaElementImpl: Configured minimum video bitrate for media transcoding: 500000 bps
0:00:24.147502721 47087 0x7fe6b00022c0 DEBUG   KurentoMediaElementImpl MediaElementImpl.cpp:699:MediaElementImpl: Configured maximum video bitrate for media transcoding: 4500000 bps

This is buggy 101

[j1elo]

Hi, I've been fixing other bug caused by newer versions of GStreamer: f226f46

Regarding this bug, please follow up in the bug tracker issue, #18