WebRTC – A viable alternative to Skype

webrtc_logoSkype for Linux 4.3 and upwards requires the use of PulseAudio, which has caused discontent amongst those Linux users who do not use PulseAudio. Although I do use PulseAudio, I recently found out about WebRTC, an API (application programming interface) for browser-based communication offering most of the functions provided by Skype, namely: voice calling, video chat, text chat, file sharing and screen sharing. The official WebRTC site states:

WebRTC is a free, open project that enables web browsers with Real-Time Communications (RTC) capabilities via simple JavaScript APIs. The WebRTC components have been optimized to best serve this purpose.

Our mission: To enable rich, high quality, RTC applications to be developed in the browser via simple JavaScript APIs and HTML5.

WebRTC was originally released by Google but is now a draft standard of the World Wide Web Consortium, and is supported by Chrome, Firefox and Opera browsers. Several commercial Web sites offer WebRTC-based communications to fee-paying customers, but I thought I would try WebRTC by using one of the so-called ‘demo’ WebRTC pages. AppRTC is a WebRTC demo page which can be reached from a link on the official WebRTC site, but I prefer Multi-Party WebRTC Demo by TokBox which offers a more polished experience with better features. Both are free to use and viable substitutes to Skype for video chatting (one-to-one or conference).

So, how do you actually use WebRTC-based sites? Below is a quick guide to get you going.

Text and video chatting

Open the following URL in Chrome or Firefox:

https://opentokrtc.com/

Enter a Room Name that is likely to be unique. I used ‘fitzchat’ (without the quotes), but you can use any name you want.

The other party or parties can do the same thing, i.e. they enter the same Room Name as you, and you will all become connected.

Alternatively, to send an e-mail invitation to someone, click on the URL at the top of the pane on the right-hand side (which is Invite: https://opentokrtc.com/fitzchat in this example, as I chose to name the Room ‘fitzchat’). The partially visible pane at the right-hand side of the browser window will slide into full view when you click on it.

That’s all there is to it. You should see a video window showing each party, and they should see the same. Each party should also be able to hear the other parties. In the top right-hand corner of each video window is an icon (microphone for you; speaker for each of the other parties) which you can click on to mute/un-mute that party.

Click on the partially visible pane at the right-hand side of the browser window. Notice the ‘chat bar’ at the bottom where you enter commands and chat text. Read the grey instructions listed near the top of the pane:

Welcome to OpenTokRTC by TokBox
Type /nick your_name to change your name
Type /list to see list of users in the room
Type /help to see a list of commands
Type /hide to hide chat bar
Type /focus to lead the group
Type /unfocus to put everybody on equal standing

For example, to give myself a meaningful name instead of the default username Guest-0120e48c which was given to me automatically, I entered the following:

/nick Fitz

Screen sharing

I found that screen sharing already works well in Chrome 36.0.1985.125 but is not yet supported in Firefox 31.0. It will be supported in Firefox 32 or 33, apparently, or you can already use Firefox Nightly providing you add the appropriate preferences via about:config.

To be able to share screens in Chrome, I had to perform two steps: enable a Chrome flag and install a Chrome extension. The two steps, which do not need to be repeated, are given below (see Ref. 1).

To enable screen sharing in Chrome, do the following:

  1. Open a new tab or window in Chrome.
  2. Copy the following link: chrome://flags/#enable-usermedia-screen-capture and paste it in the location bar.
  3. Click on the ‘Enable’ link below ‘Enable screen capture support in getUserMedia().’ at the very top of the screen.
  4. Click on the ‘Relaunch Now’ button at the bottom of the page to restart Chrome.

To install the screen sharing extension in Chrome, do the following:

  1. Launch Chrome and click on the Menu icon.
  2. Click on ‘Settings’.
  3. Click on ‘Extensions’.
  4. Click on ‘Get more extensions’ and search for ‘webrtc’.
  5. Download ‘WebRTC Desktop Sharing’.
  6. This places an icon to the right of the URL bar in Chrome.

To share your screen or just a window, do the following in Chrome:

  1. Click on the ‘Share Desktop’ icon to the right of the URL bar and select either ‘Screen’ or the window you wish to share.
  2. Click ‘Share’.
  3. When sharing has started in a new Chrome window, select the URL of the relevant tab in that window and send it to the other parties via the chat pane on the right-hand side of the first browser window.

To stop sharing, click on ‘Stop sharing’ and click on the ‘Share Desktop’ icon to the right of the URL bar to get it to return to displaying the ‘Share Desktop’ icon instead of the || (Pause) icon.

File sharing

I did not bother to try file sharing using WebRTC, but there are various Web sites you can use to do that. One such is ShareDrop, and googling will find others.

Caveats

Chrome 36.0.1985.125 and Firefox 31.0 were used in this trial (I did not try Opera). I found that video chat worked faultlessly when both parties were using Chrome, and when both parties were using Firefox. However, when one of the parties was using Firefox and the other was using Chrome, I could not see myself in one of the video boxes in the browser window (although I could see the other party in the other video box in the browser window). Furthermore, there was a grey bar across the middle of the video images in the AppRTC demo, whereas the Multi-Party WebRTC Demo video images were normal. Other than those two issues, the experience was smooth and straightforward. My recommendation would therefore be to use Multi-Party WebRTC Demo and for all the parties to use the same browser, be it Chrome or Firefox. If you want to share your screen or a window, the logical choice at the moment would be Chrome.

References

1 LiveMinutes Blog – Beta Testers: How To Activate Screen Sharing!

Fixing a problem with received video in Skype when using the AMD Catalyst (FGLRX) driver in Linux

Some users of Skype for Linux have reported that the bottom half of the received video image is corrupted in installations that use the closed-source video driver for ATI GPUs (the AMD Catalyst proprietary Linux driver, also known as the ‘FGLRX’ driver). One user described the lower half of the video image as “covered in small coloured squares like a chequer board”.

From what I have read in a few forums, it seems the problem does not occur when the open-source Radeon driver is used. My own experience corroborates that: I use the Radeon driver on one of my laptops, and received video in Skype is fine.

My main laptop has an AMD ATI Mobility Radeon HD 5650 GPU and I am using the Catalyst driver under Gentoo Linux. In this case there was a problem with received video in most Skype sessions. Either of the following effects usually occurred:

Snapshot 1 - Extract of received video image in Skype, showing an example of the corrupted image

Snapshot 1 - Extract of received video image in Skype, showing an example of the corrupted image

Snapshot 2 - Extract of received video image in Skype, showing another example of the corrupted image

Snapshot 2 - Extract of received video image in Skype, showing another example of the corrupted image

As shown in Snapshot 1, the lower half of the received video image was covered in a grid of thin green lines with areas tinged with purple, blue or green, whereas there was no grid of lines in the upper half of the image but some areas were tinged with red or blue.

As shown in Snapshot 2, the lower half of the received video image was covered in a grid of thin red lines, with a purple tinge in some areas, whereas there was no grid of lines in the upper half of the image, which looked reasonable but had some red-, green- or blue-tinged areas.

In all cases Skype’s thumbnail of my Webcam’s video image looked fine, and the person on the other end of the call said the video image received from me looked fine too.

Because of a bug in a previous version of the Catalyst driver a few years ago — see my blog posts Playing QuickTime videos in Firefox and Chromium + XVideo bug in AMD Catalyst 11.11 and 11.12 driver and AMD Catalyst for Linux driver 12.2 fixes the XVideo bug that crashed X.Org Server 1.11.x — I happen to know that Sykpe uses X11 overlays with the XVideo extension (xv), rather than using the OpenGL renderer (gl) or X11 with the SHM extension (x11). This made me wonder whether the use of XVideo with the Catalyst driver was causing the current problem. Unlike media players such as MPlayer and VLC, it is not possible to configure Skype to use gl or x11 instead of xv, so I thought it would not be possible to test whether the use of gl or x11 instead of xv would make a difference. Until, that is, I came upon a ‘trick’ posted by openSUSE user queequeg in 2009 during the period when an earlier version of the Catalyst driver had the aforementioned bug:

Skype Video Workaround for ATI

Anybody trying to make a video call with Skype and ATI fglrx drivers has had problems due to Skype using the “xv” video mode with the driver can’t handle. For anyone interested that is affected by this, there is a workaround:

1. Run the xvinfo command and look at the number of xv sessions available. Some cards have only 1, some have as many as 4. This is the number of xv occurances that the card can do at one time.
2. “Use up” all these xv sessions by opening videos in your favorite video player making sure to use xv for the video output. The videos can then be paused.
3. Once this (or they) are open, skype can be started and will default to X11 video and work properly with video calls.

I know this is a goofy way to get around this issue, but until fglrx can handle xv or skype allows an option to choose X11 for video render, I don’t know of any other way to do it.

(From what I hear, the 11.1 fglrx drivers can handle xv, but I haven’t confirmed this.)

So I tried his work-around. I had to launch four media players in order to use all available XVideo sessions. Lo and behold, when I launched Skype and made a video call the received video image was perfect. So it appeared that the Catalyst driver is not able to handle well the XVideo output from Skype. However, playing and pausing four videos every time I want to make a video call in Skype would hardly be practical, would it? And that is not the only downside: when I maximised a Firefox window during the Skype video call, my laptop spontaneously rebooted (I assume the X.Org server crashed).

I did also wonder whether just disabling compositing would solve the problem, so I disabled KWin Desktop Effects, but that didn’t make any difference.

I had also read in several forums that enabling or disabling the TexturedVideo and/or VideoOverlay options in the xorg.conf file have an effect on the video image produced by the Catalyst driver, but I could not find a post mentioning the use of either of those options to fix the specific problem I was seeing. So I decided not to pursue the xorg.conf route.

In my searches of the Web I came across a post somewhere that mentioned using GTK+ UVC Viewer (guvcview) to adjust video properties and improve video in Skype. I thought guvcview was only for adjusting the video image from a Webcam connected to my machine, i.e. adjusting the outgoing video image, and would not have any effect on received video. Nevertheless, I decided to install and launch guvcview to see if I could adjust both incoming and outgoing video properties. To my surprise, guvcview appeared to have fixed the problem with the received video. These are the steps I followed:

  1. I launched Skype and started a video call. The received video image had a grid of thin red lines and purple/green/blue tinting (similar to Snapshot 2).
  2. I Installed guvcview using the package manager.
  3. I launched guvcview in a Konsole (terminal) window. After guvcview created the file /home/fitzcarraldo/.config/guvcview/video0 and checked various video and audio settings it exited because my Webcam was being used by Skype (‘libv4l2: error setting pixformat: Device or resource busy‘).
  4. I clicked on the Webcam icon in the Skype call window, to turn my Webcam off.
  5. I launched guvcview again. The lower half of the received video image in Skype changed from a grid of thin red lines to a continuous green-coloured band, and the upper half of the image now looked reasonable but still had some red- or blue-tinged areas (see Snapshot 3 below).
  6. Snapshot 3 - Extract of received video image in Skype after I launched guvcview again

    Snapshot 3 - Extract of received video image in Skype after I launched guvcview again

  7. On the ‘Image Controls’ tab in the ‘GUVCViewer Controls’ window I changed the video frequency from 60 Hz to 50 Hz then back to 60 Hz again. I was just tinkering, and I believe this had no bearing on the outcome.
  8. I clicked on the ‘Quit’ button in the guvcview window to terminate the application.
  9. I clicked on the Webcam icon in the Skype call window to turn on again the Webcam, and the received Skype video image changed to a perfect image (see Snapshot 4 below).
  10. Snapshot 4 - Extract of received video image in Skype after I turned on again my Webcam in Skype

    Snapshot 4 - Extract of received video image in Skype after I turned on again my Webcam in Skype

It appears that guvcview had an effect on the received video image in Skype, although, if it did, I do not understand how. To check if the fix was permanent I ended the Skype video call, signed out of Skype and quit the application, rebooted and made a new Skype video call. The received video image in Skype was again perfect. I even deleted the guvcview configuration file and repeated this check, just in case the configuration file was somehow being used even though I had not launched guvcview, but the received video in yet another Skype video call was still perfect. I also clicked on the Webcam icon in the Skype call window several times during each call in order to turn my Webcam off and on several times; the received video image of the other person remained perfect.

So there you have it: when using an AMD ATI GPU and the Catalyst driver, it seems that guvcview can be used — at least in my case — to eliminate the type of image corruption in received Skype video shown in Snapshots 1 and 2. So, if you are also using the AMD Catalyst for Linux driver and are experiencing a similar problem, try guvcview. It might just do the trick.

AMD Catalyst for Linux driver 12.2 fixes the XVideo bug that crashed X.Org Server 1.11.x

Just a brief ‘heads up’ for users of the closed-source FGLRX driver in Linux: In a previous blog post I mentioned a bug in the AMD Catalyst driver for Linux that caused X.Org Server 1.11.x to crash if you tried to play a video and your media player was configured to use XVideo (Xv) output. The bug also meant that people talking to you via Skype could not enable their Web cams or X.Org Server 1.11.x would crash on your machine, as Skype uses XVideo.

The problem occurred with versions 11.11, 11.12 and 12.1 of the FGLRX driver (the package x11-drivers/ati-drivers). Well, today I installed version 12.2 of the driver and am pleased to report that I can again set media players to use Xv output without causing the X.Org Server to crash (I’m currently using xorg-server-1.11.4). Likewise, other people who I am talking to via Skype can again enable their Web cams without causing the X.Org Server on my machine to crash.

Playing QuickTime videos in Firefox and Chromium + XVideo bug in AMD Catalyst 11.11 and 11.12 driver

Video problems seem to be perennial in Linux. The latest two to affect me were:

1) Firefox and Chromium could no longer play QuickTime videos on the Apple iTunes Movie Trailers Web site;

2) a bug in the latest two releases of the closed-source ATI FGLRX driver (AMD Catalyst 11.11 and 11.12 for Linux) that causes the X.Org Server to crash when I try to play .mov files using XVideo (Xv) output in media players such as SMPlayer, VLC, GNOME-MPlayer etc. (see e.g. Gentoo Bug Report No. 391193).

The reason I mention these two problems in the same breath is because I encountered the second whilst trying to fix the first. Anyway, below I explain what I did to resolve the two problems.

I first had a problem displaying QuickTime movie trailers in Firefox a couple of years ago. The solution then was to install the User Agent Switcher add-on for Firefox and create a user agent to fool the Apple Web site into thinking Firefox was using Apple’s QuickTime browser plugin instead of mplayerplug-in for Linux. But within a few days Firefox again could not play movie trailers on the Apple Web site. I had to uninstall mplayerplug-in and install the then latest version of its successor, gecko-mediaplayer (which uses gnome-mplayer). All was good again until…

Several months ago I found that, yet again, Firefox could not play movie trailers on the Apple Web site. I tried to view the trailers in Chromium instead but had the same problem. Both browsers just displayed a black box where the video should be playing. A little searching on the Web led me to the conclusion that the problem lay with the latest version of gecko-mediaplayer and gnome-mplayer that I was using at the time, so I gave up and decided to wait for new versions of gecko-mediaplayer and gnome-mplayer to be released.

Now, yesterday I wanted to watch a particular trailer on the Apple Web site, but, despite having installed the latest version of gecko-mediaplayer and gnome-mplayer anyway a few days ago, neither Firefox nor Chromium would display the trailer. A little searching on the Web suggested that I should try mozplugger instead of gecko-mediaplayer, so I uninstalled the latter, installed mozplugger and… the black box in the browser was replaced by a white box displaying the QuickTime ‘Q’ logo and a message that I needed to install QuickTime. Argghh!

So I uninstalled mozplugger and reinstalled gecko-mediaplayer and gnome-mplayer (the same versions that I installed recently, you inderstand). This time my attempts to watch trailers on the Apple Web site resulted in Firefox and Chromium displaying grey boxes and appearing to download the QuickTime videos, but then the X.Org Server crashed, restarted and the Desktop Environment’s login screen appeared. Furthermore, when I tried playing .mov videos in VLC, the same thing happened. Perhaps now you may understand why I mentioned above the bug with the FGLRX driver? It took me a few hours to realise there were two separate problems here.

The work-around to the second problem was to configure media players to use a different output driver rather than the XVideo (Xv) output driver. For example, in VLC this is done via Tools > Preferences > Video and selecting ‘GLX video output (XCB)’ as the Output under Video Settings. For SMPlayer this is done via Options > Preferences > General and selecting ‘gl (fast – ATI cards)’ as the Output driver under the Video tab.

And, most importantly, in order to enable gecko-mediaplayer to display those Apple QuickTime trailers in Firefox and Chromium I had to launch gnome-mplayer, select Edit > Preferences, click on the Player tab and select ‘gl’ as the Video Output under Adjust Output Settings. Actually, clicking on the MPlayer tab and entering “-vo gl” (without the quotes) in the ‘Extra Options to MPlayer:’ box achieves the same result. By the way, the tickboxes QuickTime Emulation, RealPlayer Emulation, Windows Media Player Emulation and DIVX Player Emulation were already ticked on the Plug-in tab.

So, there you have it. After several hours of searching and tinkering I can again watch movie trailers on the Apple Web site. Don’t you just love Linux?

For the sake of completeness, below I list the versions of the applicable packages currently installed on my main laptop:

firefox-9.0
chromium-16.0.912.63
gecko-mediaplayer-1.0.5_beta1_p20111207
gnome-mplayer-1.0.5_beta1
mplayer-1.0_rc4_p20111215
ffmpeg-0.9
libquicktime-1.2.3-r1
xorg-server-1.11.2-r2
ati-drivers-11.12

EDIT (January 2, 2012): I’ve just had a thought: When I used Skype for Linux a few days ago, my laptop rebooted spontaneously as soon as the person at the other end enabled her Webcam in Skype for Windows. This was reproducible consistently. However, I could enable my Webcam, she could see me in Skype on her PC, and I could also see video of me in Skype’s ‘myself preview’ on my laptop. Now, it could be a coincidence but I wonder if the reboot occurred because Skype for Linux uses XVideo? Skype’s Web page for Skype for Linux lists “Video card driver with Xv support” as one of the hardware requirements, which looks pretty conclusive to me. However, this leaves a couple of niggling questions: a) If Skype does indeed use XVideo, why didn’t the ‘myself preview’ video in the Skype for Linux window crash the X.Org Server?. b) If the FGLRX driver bug is the cause, why did my laptop reboot instead of just the X.Org Server crashing, restarting and displaying the Desktop Environment login screen? Furthermore, Skype’s Options > Video Devices > Test does work correctly on my laptop. So perhaps the rebooting problem is caused by a different bug. Suspicious, though. Unfortunately, as far as I know there is no way of switching Skype to use OpenGL instead of XVideo, so I cannot prove that XVideo is the cause of this particular problem I’m experiencing with Skype.

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