WebRTC videotestsrc freezes with gst-launch-1.0 but not with gst-launch-0.10 #251

wehlutyk · 2020-01-30T11:30:33Z

First of all, thanks for the great module! Lots of fun stuff can be done with this. Now I've been all over SO and the issues here, to no avail with this.

Environment

v4l2loopback version: 0.12.3
kernel version: Linux keon 4.19.99-1-lts #1 SMP Mon, 27 Jan 2020 21:30:28 +0000 x86_64 GNU/Linux

Distribution (+version):

LSB Version:	1.4
Distributor ID:	Arch
Description:	Arch Linux
Release:	rolling
Codename:	n/a

Problem

Ultimately, I want to feed GStreamer's videotestsrc to a WebRTC conference (videotestsrc for now, and ultimately an incoming RTMP stream).

To test using videotestsrc as a webcam in the browser, I run:

sudo modprobe v4l2loopback exclusive_caps=1
gst-launch-1.0 videotestsrc ! v4l2sink device=/dev/video2  # with or without identity drop-allocation=1, if there is an error

Then I open the following webpage:

<!doctype html>
<html>
  <head>
    <title>WebRTC video test</title>
    <meta charset='utf-8'>
  </head>
  <body>
    <div class="contentarea">
      <video id="video">Video stream not available.</video>
    </div>
    <script>
      navigator.mediaDevices.getUserMedia({video: true})
      .then(function(mediaStream) {
        var video = document.querySelector('video');
        video.srcObject = mediaStream;
        video.onloadedmetadata = function(e) {
          video.play();
        };
      })
      .catch(function(err) { console.log(err.name + ": " + err.message); });
    </script>
  </body>
</html>

In the browser, the v4l2loopback device appears as an option for webcams, so I select it.

Observed Results

A single video frame is shown (the test pattern) after which the video freezes. I expect the video to run.

If instead I use gst-launch-0.10 videotestsrc ! v4l2sink device=/dev/video2 (so GStreamer 0.10), the video plays in the browser.

Relevant logs

In case the caps used are useful:

gst-launch-1.0 -v videotestsrc ! v4l2sink device=/dev/video2
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
/GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0.GstPad:src: caps = video/x-raw, format=(string)YUY2, width=(int)320, height=(int)240, framerate=(fraction)30/1, multiview-mode=(string)mono, interlace-mode=(string)progressive, colorimetry=(string)2:4:7:1, pixel-aspect-ratio=(fraction)1/1
/GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0.GstPad:sink: caps = video/x-raw, format=(string)YUY2, width=(int)320, height=(int)240, framerate=(fraction)30/1, multiview-mode=(string)mono, interlace-mode=(string)progressive, colorimetry=(string)2:4:7:1, pixel-aspect-ratio=(fraction)1/1
Pipeline is PREROLLED ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock

$ gst-launch-0.10 -v videotestsrc ! v4l2sink device=/dev/video2
Setting pipeline to PAUSED ...
/GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0.GstPad:src: caps = video/x-raw-yuv, format=(fourcc)YUY2, width=(int)320, height=(int)240, interlaced=(boolean)false, pixel-aspect-ratio=(fraction)1/1, framerate=(fraction)30/1, color-matrix=(string)sdtv, chroma-site=(string)mpeg2
Pipeline is PREROLLING ...
/GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0: queue-size = 8
/GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0.GstPad:sink: caps = video/x-raw-yuv, format=(fourcc)YUY2, width=(int)320, height=(int)240, interlaced=(boolean)false, pixel-aspect-ratio=(fraction)1/1, framerate=(fraction)30/1, color-matrix=(string)sdtv, chroma-site=(string)mpeg2
Pipeline is PREROLLED ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock

The text was updated successfully, but these errors were encountered:

umlaeute · 2020-01-30T19:52:33Z

did you try setting max_buffers=2? (i'm thinking of making this the default)

umlaeute · 2020-01-30T20:42:24Z

which browsers did you try?
while i get occasional blocks with firefox, chromium (chrome) doesn't seem to have this problem.

wehlutyk · 2020-01-30T21:29:43Z

So

$ sudo modprobe v4l2loopback exclusive_caps=1 max_buffers=2
$ gst-launch-1.0 -v videotestsrc ! v4l2sink device=/dev/video2

Same behaviour.

I tested Firefox, and the device doesn't show up in Chromium (looks like the Chromium bug linked to in #78).

Surprisingly, it does show up in jitsi-meet which is an Electron app, and the video preview shows a running videotestsrc in the source-selection modal dialog, but after validating the app goes back to the physical webcam source (after sometimes showing a single frame from videotestsrc).

umlaeute · 2020-01-30T21:53:48Z

just to be sure: you did unload the v4l2loopback module before running modprobe again?

wehlutyk · 2020-01-30T22:22:52Z

Yes I did

$ sudo modprobe -r v4l2loopback              
[sudo] password for sl: 
$ sudo modprobe v4l2loopback exclusive_caps=1 max_buffers=2
$ gst-launch-1.0 -v videotestsrc ! v4l2sink device=/dev/video2
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
/GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0.GstPad:src: caps = video/x-raw, format=(string)YUY2, width=(int)320, height=(int)240, framerate=(fraction)30/1, multiview-mode=(string)mono, interlace-mode=(string)progressive, colorimetry=(string)2:4:7:1, pixel-aspect-ratio=(fraction)1/1
/GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0.GstPad:sink: caps = video/x-raw, format=(string)YUY2, width=(int)320, height=(int)240, framerate=(fraction)30/1, multiview-mode=(string)mono, interlace-mode=(string)progressive, colorimetry=(string)2:4:7:1, pixel-aspect-ratio=(fraction)1/1
Pipeline is PREROLLED ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock

# This is when I try Firefox

^Chandling interrupt.
Interrupt: Stopping pipeline ...
Execution ended after 0:00:18.079773332
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...

Edit: add logs

Edit 2: (I get that you check for this!)

wehlutyk · 2020-01-30T22:36:36Z

I should add that in both cases (GStreamer 0.10 and 1.0) VLC can read the capture device and the video plays (so it's only when reading it in Firefox that I see this behaviour). Could VLC help me debug this?

Edit: phrasing

Wallacy · 2020-02-07T23:48:54Z

did you try setting max_buffers=2? (i'm thinking of making this the default)

Not related to this thread but max_buffers=2 solved some issues on my pipeline. Also, will be nice to make MAX_DEVICES configurable too.

f8ith · 2020-02-11T05:31:41Z

I also have this issue

did you try setting max_buffers=2? (i'm thinking of making this the default)

I also loaded the module with max_buffers=2 to no avail.
The specific command I ran is this: "sudo modprobe v4l2loopback exclusive_caps=1 devices=1 max_buffers=2"
The device works perfectly in Brave (Chromium derivative) but freezes in Firefox.

Related: #166 Related: #251 Related: #261 and probably others...

umlaeute mentioned this issue Mar 15, 2020

gst-launch-1.0 v4l2src stops after start #261

Closed

umlaeute added a commit that referenced this issue Mar 16, 2020

Set the default number of buffers to 2

e4f2c3c

Related: #166 Related: #251 Related: #261 and probably others...

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WebRTC videotestsrc freezes with gst-launch-1.0 but not with gst-launch-0.10 #251

WebRTC videotestsrc freezes with gst-launch-1.0 but not with gst-launch-0.10 #251

wehlutyk commented Jan 30, 2020

umlaeute commented Jan 30, 2020

umlaeute commented Jan 30, 2020

wehlutyk commented Jan 30, 2020

umlaeute commented Jan 30, 2020

wehlutyk commented Jan 30, 2020 •

edited

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wehlutyk commented Jan 30, 2020 •

edited

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Wallacy commented Feb 7, 2020 •

edited

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f8ith commented Feb 11, 2020

WebRTC videotestsrc freezes with gst-launch-1.0 but not with gst-launch-0.10 #251

WebRTC videotestsrc freezes with gst-launch-1.0 but not with gst-launch-0.10 #251

Comments

wehlutyk commented Jan 30, 2020

Environment

Problem

Observed Results

Relevant logs

umlaeute commented Jan 30, 2020

umlaeute commented Jan 30, 2020

wehlutyk commented Jan 30, 2020

umlaeute commented Jan 30, 2020

wehlutyk commented Jan 30, 2020 • edited Loading

wehlutyk commented Jan 30, 2020 • edited Loading

Wallacy commented Feb 7, 2020 • edited Loading

f8ith commented Feb 11, 2020

wehlutyk commented Jan 30, 2020 •

edited

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wehlutyk commented Jan 30, 2020 •

edited

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Wallacy commented Feb 7, 2020 •

edited

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