Videotestsrc takes several minutes to send the first frame

General Discussion
1

When I use a custom appsrc, the client receives a sample quickly. But when videotestsrc is used, it takes several minutes. I wonder what the cause could be.

Server

    pipeline_str = g_strdup_printf("videotestsrc ! " //
                                   "queue ! " //
                                   "videoconvert ! " //
                                   "video/x-raw,format=NV12 ! " //
                                   "queue ! " //
                                   "x264enc tune=zerolatency ! " //
                                   "video/x-h264,profile=baseline ! " //
                                   "queue ! " //
                                   "h264parse ! " //
                                   "rtph264pay config-interval=1 ! " //
                                   "application/x-rtp,payload=96 ! " //
                                   "tee name=%s allow-not-linked=true",
                                   WEBRTC_TEE_NAME);

    // No webrtc bin yet until later!

Client

        ws_state.pipeline = gst_parse_launch(
            "webrtcbin name=webrtc bundle-policy=max-bundle ! "
            "rtph264depay ! "
            "h264parse ! "
            "avdec_h264 ! " // sudo apt install gstreamer1.0-libav
            "autovideosink",
            &error);
2

If anyone is interested, here’s the repos:

Thanks in advance!

3

You may try setting x264enc property key-int-max for it to make a key frame at shorter intervals, such as:

... ! x264enc key-int-max=30 ...

for a key frame each 30 frames.

4

Unfortunately this doesn’t work. If I add

"tee name=tp tp. ! queue! autovideosink tp. ! "

after videotestsrc to show the test video on the server side, the client side will pop up the video window soon. This is weird.

5

Does the issue happen even if the server has been up a couple of minutes before running the client?
I’m wondering if the issue is due to problems with the videotestsrc doing the PREROLL correctly.

6

Yes, it still happens. And when I use filesrc instead of videotestsrc, there’s no video at all and the pipeline is kind of broken.

linux_file_src_image
linux_file_src_image23483×1140 1.01 MB

The pipeline for videotestsrc is as follows.

image
image16177×1436 918 KB

And again, if I add the beforementioned autovideosink, filesrc does work.

7

The delay would be gone if I don’t use dynamic pipeline. webrtcbin is really a mess

8

Have you tried is-live=true on videotestsrc?

1 Like
9

is-live=true definitely works! I wonder what this means