Question / Help Help with Answers to Common Questions [Facebook Live]

[Ian Anderson Gray]

Hi everyone.

In June I wrote a post on how to use OBS Studio to broadcast to Facebook Live. It's ended up being really popular and it has over 600 comments. I've launched a course too with an active members group.

Basically, I'm getting lots of questions in the comments, in my group and by email. I've been able to answer most of those, but I want to be more helpful and was hoping to get some help with some of the following! Then I can be of better help to these people.

Here are the questions:

1) Can't connect to FB Live - Some people either get a "cannot connect to server" error message or the Facebook Live preview window. Something is obviously blocking the connection but it's hard to give helpful advice. My feeling is that in many situations, the users' ISP is blocking port 1935. Is there an easy non-techie way to work out what the issue is? I don't want to scare people with really advanced command line stuff. I came across Steve Gibson's Shields Up and this tells you if your port is closed - https://www.grc.com/x/portprobe=1935 but I don't know if this is the actual issue. So, what are the common reasons for people not being able to connect? And if it is their ISP that is blocking port 1935, what is the best way to ask them to unblock it?

2) Webcam screen is black - Some people have contacted me to say that there webcam is black when they add it as a source. More often than not, it's because their webcam is being used by another device such as Skype. In some cases this is not the case and there is another issue. What could be causing this? And is there an app for Mac and PCs that allow you to share your webcam between apps such as Skype and OBS? I know Sparkocam does this but it isn't available for Mac.

3) Audio/Video out of sync - This is probably my 2nd most common question after (1). What is the biggest reason for the audio and video to be out of sync? I think not enough processing power might have something to do with it and I've recommended increasing the encoding preset to superfast or ultrafast. Is this a helpful recommendation? Obviously a more powerful processor would help. I've also recommended closing down as many apps running in the background. Then there is the manual audio offset option in the mixer options. Can bandwidth play a part here? Are there any better settings and encoder presets that can help?

4) Lag between computer and Facebook Live - I know there is always going to be a lag between what you're sending and what visitors see. I'd say a 5-10 second lag would be normal. But some people are getting a 3 minute lag. That's a long time! Could that be due to a number of factors such as internet upload speed, CPU power, encoding speed etc? Is there a way to improve this and troubleshoot?

5) Does OBS Studio use my GPU - OK, this isn't a common question, but I'd like to ask. Does OBS Studio make use of dedicated graphics like Wirecast does? If not, are there any plans to do so and improve the stream quality and speed?

Thanks so much!

Ian

 

[Harold]

Facebook doesn't have their rtmp ingests listening on 1935.

 

[Ian Anderson Gray]

Yes, that's what I thought. Although Facebook Live uses RTMP, the stream url is port 80. However, I spoke with Wirecast and they definitely require port 1935 to be open for Facebook Live. I've also found that port 1935 being blocked is a usual reason for people not being able to connect.
I wish I could get to the bottom of it and understand more what is happening.

 

[RytoEX]

Hi! Loved your blog post on the topic, and your convenient button for streaming as a User rather than a Page.

I'll try to answer what I can. Of course, if I say something incorrect, anyone is free to correct me.

2) Webcam screen is black - Some people have contacted me to say that there webcam is black when they add it as a source. More often than not, it's because their webcam is being used by another device such as Skype. In some cases this is not the case and there is another issue. What could be causing this? And is there an app for Mac and PCs that allow you to share your webcam between apps such as Skype and OBS? I know Sparkocam does this but it isn't available for Mac.

5) Does OBS Studio use my GPU - OK, this isn't a common question, but I'd like to ask. Does OBS Studio make use of dedicated graphics like Wirecast does? If not, are there any plans to do so and improve the stream quality and speed?

For #2, you've already kind of given the answer. In some cases, another device has accessed the camera and has exclusive access. In other cases, well, that could be a side effect of the new Frame Server behavior in Windows 10 AU? The intended behavior of the new Frame Server stuff in Windows 10 AU was to give applications the ability to share the webcam at the OS-level by intercepting the camera's data and then passing that out to applications that request it. Unfortunately, it had the unintended side effect of breaking the majority of webcams and software that worked with them. It's a long-shot, but see this thread and its links (and their links...) for details. It could just be that the camera, drivers, or OBS are expecting the camera's output in one format, but that format is no longer exposed, so it comes back black. Of course, I could also be entirely wrong.

For #5, as far as I know, yes. OBS Studio uses the GPU for compositing and rendering. It can also use the GPU for encoding (Nvidia NVENC or AMD VCE), if your GPU supports that and you have configured OBS Studio to do so. Though, using the GPU for encoding (or any PC hardware encoding) for livestreams has had mixed results, especially on older hardware and lower bitrates. Your mileage may vary.

Yes, that's what I thought. Although Facebook Live uses RTMP, the stream url is port 80. However, I spoke with Wirecast and they definitely require port 1935 to be open for Facebook Live. I've also found that port 1935 being blocked is a usual reason for people not being able to connect.
I wish I could get to the bottom of it and understand more what is happening.

Instead of asking Wirecast why they require port 1935 open for Facebook Live, you should ask Facebook what ports they require open to stream to Facebook Live. If Wirecast is adding some additional requirement that is not in Facebook's specification, then that's a Wirecast problem.

 

[Ian Anderson Gray]

Thanks for your reply. So glad you enjoyed my blog post.

Glad I am thinking along the right lines with (2). I'm able to help with Windows machines, but a lot of my readers are Mac owners so I wondered if there were different issues with Macs.

I am glad OBS uses the GPU. In my comparison, Wirecast does seem to give a smoother stream, but I suppose you'd expect that in a $500 product. Hopefully OBS Studio will continue to improve the encoding side of things. You say if your GPU supports encoding you can configure OBS Studio to do so. I can't see where you can set this? Can you let me know?

As for my final question, this is what gives me the most frustration. I'm not an expert when it comes to ports and networking and I've been trying to find out what the issue is here. I do know that port 80 is used in the stream URL for Facebook, but it still seams that port 1935 is being used or at least something is blocking the connection for some users. I am pretty sure some ISPs are blocking the connection because some users contacted their ISPs and then they were magically able to connect. You say I should ask Facebook. However, Facebook are not known for their customer services. I can't get a response from then. The reason I asked Wirecast was because I was in touch with their support team and I figured they would use a similar set up to OBS Studio. They could be telling me incorrect information of course.
So, if OBS Studio is only using port 80 to connect to Facebook Live, what is causing the issues for all these people? It's a mystery and I wish I could find out how to help these people.

 

[RytoEX]

I am glad OBS uses the GPU. In my comparison, Wirecast does seem to give a smoother stream, but I suppose you'd expect that in a $500 product. Hopefully OBS Studio will continue to improve the encoding side of things. You say if your GPU supports encoding you can configure OBS Studio to do so. I can't see where you can set this? Can you let me know?

If you have an AMD or Nvidia GPU that supports GPU encoding, it would show up in the Encoder options. Under Simple Output Mode, they would say "Hardware" followed by the encoder (NVENC for Nvidia, I don't know what AMD's says). In Advanced Output Mode, the Nvidia hardware encoder is "NVENC H.264". You can also use Intel's onboard CPU/graphics for Quick Sync encoding, if your system supports it. It would be configured in the same place, but may require changing some BIOS settings for it to appear.

For a good information on high quality local recordings using hardware encoders, I recommend this guide. Please keep in mind that streaming settings would probably need to be different.

A word of caution: Hardware encoding, in general, is still kind of in its infancy. Using it for streaming does not always provide great results, especially on older hardware running older versions of the encoder standards, but getting end-users to differentiate those details is difficult.

As for my final question, this is what gives me the most frustration. I'm not an expert when it comes to ports and networking and I've been trying to find out what the issue is here. I do know that port 80 is used in the stream URL for Facebook, but it still seams that port 1935 is being used or at least something is blocking the connection for some users. I am pretty sure some ISPs are blocking the connection because some users contacted their ISPs and then they were magically able to connect. You say I should ask Facebook. However, Facebook are not known for their customer services. I can't get a response from then. The reason I asked Wirecast was because I was in touch with their support team and I figured they would use a similar set up to OBS Studio. They could be telling me incorrect information of course.
So, if OBS Studio is only using port 80 to connect to Facebook Live, what is causing the issues for all these people? It's a mystery and I wish I could find out how to help these people.

I'm not exactly up to speed on the code OBS Studio uses to make such connections. If you're curious, you (or someone else) could probably run WireShark or some other network traffic monitoring software to check what traffic is going out on what ports during a Facebook Live session.

 

[RickyF]

Having sound sync issues using OBS on mac. I don't really need high quality video or sound and want to know how best to reduce quality to get audio sync. Any specific suggestions would be deeply appreciated.

 

[RicardoK]

Hi,

I looked at the guide https://obsproject.com/forum/resour...lity-recording-and-multiple-audio-tracks.221/ and I'm trying to understand the different options. I hope it's ok to post in this thread given my question is related to Facebook live.

The high quality guide suggests using CRF for h264. Is there a way to control the bitrate in OBS if I use CRF? I currently use CBR for my FB live setting.

Does anyone know the difference between h264 and QuickSync h264? Those are the only 2 options I see available to me on my system.