FORUMS: list search recent posts

Stream breaks up when switching from still to live image

COW Forums : Telestream Wirecast

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Chuck Pullen
Stream breaks up when switching from still to live image
on Jan 23, 2014 at 1:01:40 pm

I had an event last night where we pulled all of the PowerPoint slides in to Wirecast and were switching back and forth between the stills and a live camera fed to Wirecast over SDI via a DeckLink Extreme card.

We were streaming to a free channel on "Original" Livestream. There were many complaints by the viewers stating the stream fell apart whenever we cut to the speaker. In watching the recorded stream now:
(http://www.livestream.com/c2st) I am seeing the exact same issue. I was on a hardline at a major university, so bandwidth was not an issue on their end.

Thoughts on how to correct this so I do not lose this client?

Chuck Pullen


Return to posts index

Craig Seeman
Re: Stream breaks up when switching from still to live image
on Jan 23, 2014 at 4:12:45 pm
Last Edited By Craig Seeman on Jan 23, 2014 at 4:14:12 pm

Impossible to know without technical information. I can probably think of a dozen reasons for your issues.

Describe as if you wanted a blind person to build a matching system including hardware, software versions, settings.

If it's only on transitions it might be related to the format of the stills requiring a sudden radical change in the encoder when cutting for example. It could be too low a data rate. The transition would have impact on what's happening in the GOP. It could be you're not current with Wirecast version. It could be the driver for your camera input device and Wirecast accessing it on the switch.

I've been using Wirecast with Original Livestream (I have premium account) for years and haven't had anything like this. This is across multiple computers, multiple input devices (webcam, DVCam, BMD Mini Recorder, MXO2-LE). Usually streaming at 640x360 at 500 to 800 kbps depending on content. I've used recorded clips but don't use stills much so I suspect the issue is related to stills to live video and your settings or equipment.


ALWAYS test before you go live using the sources and setup you plan to use. This is something that should be caught in advance, giving you time to tweak settings.


Return to posts index

Chuck Pullen
Re: Stream breaks up when switching from still to live image
on Jan 23, 2014 at 5:13:35 pm

I'm running the newest version 4 on a pretty decent machine (off the top of my head)it has i7, 12 GB, RAM, a 1GB video card. CPU usage is under 30% when streaming. I am doing everything at 720p, maybe I should scale down what I am sending to Livestream?

Normally when I show PP slides, I bring them through a switcher which feeds a single SDI to the Wirecast machine. This is the first time I tried importing slides into Wirecast. Even then, usually when we have bandwidth issues, the audio remains solid, but the image may degrade for a short period.

During our testing it worked fine, but I think that was because we were switching between the slides and a static image on camera. Once we introduced the motion from the speaker, that's when I had issues.

What would your initial suspicions be? I am thinking it is the 720p image being sent to a free Livestream account limited to 500k.?

Chuck

P.S. I am starting a separate thread regarding the use of New Livestream I would love your opinion on.


Return to posts index


Craig Seeman
Re: Stream breaks up when switching from still to live image
on Jan 23, 2014 at 5:39:12 pm

[Chuck Pullen] " am doing everything at 720p, maybe I should scale down what I am sending to Livestream?"

Free Original Livestream doesn't support HD. That means your video is being downscaled. 640x360 should closely match their player I believe.

[Chuck Pullen] "This is the first time I tried importing slides into Wirecast. Even then, usually when we have bandwidth issues,"

Perhaps the slides are too large or in a codec that's causing issues on the switch. You may need to downscale the slides. Make sure they are 72dpi as anything higher is a waste and possibly a stress, Frame size should be such that there isn't much downscaling to fit into the encoder. Canvas should match either input source or the encoder depending on which scales better.

I'm not sure what you mean by bandwidth issue since I thought your first post implied there should be none. ALWAYS test before streaming.

Speed
http://www.speedtest.net
Packet loss
http://www.pingtest.net



[Chuck Pullen] "I am thinking it is the 720p image being sent to a free Livestream account limited to 500k.?"

I believe free accounts not using their own software are limited to 500kbps. That would mean your encoder should probably be 640x360 at 500kbps combined for audio and video.



Return to posts index

Chuck Pullen
Re: Stream breaks up when switching from still to live image
on Jan 23, 2014 at 5:47:54 pm

Thanks Craig, I am going to tweak the output settings and see what happens.

This is a flypack unit, so what I meant by bandwidth issues, is that when we do have a location with bandwidth issues, it is usually the video that stutters but the audio remains intact. Speedtest showed well over 10 MB up last night, so I highly doubt bandwidth was the issue.

This is the first time that I have seen the entire stream "fall apart" like that on the return feed. Hopefully a tweak to the output will clear this up.

Chuck


Return to posts index

Craig Seeman
Re: Stream breaks up when switching from still to live image
on Jan 23, 2014 at 6:29:33 pm

[Chuck Pullen] " Speedtest showed well over 10 MB up last night, so I highly doubt bandwidth was the issue."

Packet loss can be a problem. Always should be 0%

[Chuck Pullen] "This is the first time that I have seen the entire stream "fall apart" like that on the return feed"

What was new, the slides? Size and source codec might have been the problem impacting the transitions.



Return to posts index


Chuck Pullen
Re: Stream breaks up when switching from still to live image
on Jan 23, 2014 at 6:33:58 pm

[Craig Seeman] "Packet loss can be a problem. Always should be 0%"

How do I check for that?



[Craig Seeman] "What was new, the slides? Size and source codec might have been the problem impacting the transitions."

Yes the process of having the slides on Wirecast and not external was new last night. I was thinking that when Wirecast is receiving a single SDI input from a switcher, the signal received would be at a constant bit-rate. but switching from a still to live is causing a massive bit-rate fluctuation, and something can't handle it?


Chuck


Return to posts index

Craig Seeman
Re: Stream breaks up when switching from still to live image
on Jan 23, 2014 at 6:42:36 pm

[Chuck Pullen] "Craig Seeman] "Packet loss can be a problem. Always should be 0%"

How do I check for that?"


Posted the link in an earlier post "Pingtest"

[Chuck Pullen] "but switching from a still to live is causing a massive bit-rate fluctuation, and something can't handle it?"

Wirecast generally handles this assuming the sources are set up OK. You have to test that. Many stills may be way too big and that can cause issues with the rapid change in source material.



Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]