CODEWITHSUNDEEP
gstreamermjpeg
DerLars
DerLars

Reputation: 21

Gstreamer capture and store mjpeg from webcam

I am trying to capture and store a webcam stream. The requirements are 1920x1080@30fps. And it must be done by a single-board-computer (Raspberry). The duration to capture is 10 minutes. (For the moment I only capture 10 seconds for testing)

In general the camera (usbfhd01m from ELP) is able to provide an MJPEG stream in 1920x1080@30fps. I am just not able to store it. And I don't know why. I tried it with the following pipeline:

gst-launch-1.0 v4l2src device=/dev/video0 num-buffers=300 do-timestamp=true ! image/jpeg,width=1920,height=1080,framerate=30/1 ! queue ! avimux ! filesink location=test.avi

The result is a video file which is far away from being fluent. What is missing in my pipeline?

When I use the same pipeline, but decode the stream and save it in a raw file like this:

gst-launch-1.0 v4l2src device=/dev/video0 num-buffers=300 do-timestamp=true ! image/jpeg,width=1920,height=1080,framerate=30/1 ! queue ! jpegdec ! filesink location=test.yuv

then the raw video is absolutely fluent. Therefore, I think the pipeline and the device is able to record in 1920x1080@30fps, but there seems to be something wrong for saving the stream.

Storing the stream into matroska fileformat does not change my problem. And for transcoding on the fly to H264 the Raspberry Pi 3 doesn't seem to be powerful enough. (Even by using omxh264enc)

Upvotes: 2

Views: 7952

Answers (1)

Florian Zwoch
Florian Zwoch

Reputation: 7373

What happens when you remove the do-timestamp=true? This options applies current pipeline timestamps to the sample buffers - overwriting those coming out from the device. You probably want to store the original timestamps instead of overwriting them as they can carry some pipeline jitter.

In your second pipeline you save the stream as raw. Basically removing all timestamp information that you have (also the jitter timestamps). So when you play back the raw stream it assumes a constant framerate instead.

Upvotes: 1

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