v4l2src lost frames on raspberrypi zero wifi

[Dengke Du]

Hi all

Gstreamer version: 1.14.2

My device info: v4l2-ctl --list-formats

ioctl: VIDIOC_ENUM_FMT
     Index       : 0
     Type        : Video Capture
     Pixel Format: 'YUYV'
     Name        : YUYV 4:2:2

     Index       : 1
     Type        : Video Capture
     Pixel Format: 'MJPG' (compressed)
     Name        : Motion-JPEG

Raspberry zero wifi as a server side:

     runing: GST_DEBUG=3 test-launch "( v4l2src ! image/jpeg ! jpegdec ! 
x264enc tune=zerolatency ! rtph264pay name=pay0 pt=96 )"

Ubuntu 16.04 as a client side:

     runing: gst-launch-1.0 rtspsrc location="rtsp://rasp-ip:8554/test" 
latency=0 ! rtph264depay ! decodebin ! videoconvert ! ximagesink

The server side show the following:

--------------------------------------------------------------------------------------

root at raspberrypi0-wifi:~# GST_DEBUG=3 test-launch "( v4l2src ! 
image/jpeg ! jpegdec ! x264enc tune=zerolatency ! rtph264pay name=pay0 
pt=96 )"
stream ready at rtsp://127.0.0.1:8554/test
0:01:30.683202000   305 0xb4e0ee90 FIXME           videodecoder 
gstvideodecoder.c:933:gst_video_decoder_drain_out:<jpegdec0> Sub-class 
should implement drain()
0:01:30.718953000   305 0xb4e0ee90 WARN          v4l2bufferpool 
gstv4l2bufferpool.c:790:gst_v4l2_buffer_pool_start:<v4l2src0:pool:src> 
Uncertain or not enough buffers, enabling copy threshold
0:01:31.065635000   305 0xb4e0ee90 FIXME           videodecoder 
gstvideodecoder.c:933:gst_video_decoder_drain_out:<jpegdec0> Sub-class 
should implement drain()
0:01:32.019512000   305  0x1ba0290 FIXME              rtspmedia 
rtsp-media.c:3835:gst_rtsp_media_suspend: suspend for dynamic pipelines 
needs fixing
0:01:32.035965000   305  0x1ba0290 FIXME              rtspmedia 
rtsp-media.c:3835:gst_rtsp_media_suspend: suspend for dynamic pipelines 
needs fixing
0:01:32.038393000   305  0x1ba0290 WARN               rtspmedia 
rtsp-media.c:3861:gst_rtsp_media_suspend: media 0xb5c2f1c0 was not prepared
0:01:32.106016000   305  0x1ba0290 FIXME             rtspclient 
rtsp-client.c:1646:handle_play_request:<GstRTSPClient at 0x1ca0878> Add 
support for seek style (null)
0:01:32.109618000   305  0x1ba0290 FIXME              rtspmedia 
rtsp-media.c:2434:gst_rtsp_media_seek_full:<GstRTSPMedia at 0xb5c2f1c0> 
Handle going back to 0 for none live not seekable streams.
0:01:44.798303000   305 0xb4e0ee90 WARN                 v4l2src 
gstv4l2src.c:911:gst_v4l2src_create:<v4l2src0> Timestamp does not 
correlate with any clock, ignoring driver timestamps
0:01:44.800910000   305 0xb4e0ee90 WARN                 v4l2src 
gstv4l2src.c:976:gst_v4l2src_create:<v4l2src0> lost frames detected: 
count = 22 - ts: 0:00:14.088149667
0:01:48.783236000   305 0xb4e0ee90 WARN                 v4l2src 
gstv4l2src.c:976:gst_v4l2src_create:<v4l2src0> lost frames detected: 
count = 59 - ts: 0:00:18.072994667
0:01:50.959261000   305 0xb4e0ee90 WARN                 v4l2src 
gstv4l2src.c:976:gst_v4l2src_create:<v4l2src0> lost frames detected: 
count = 74 - ts: 0:00:20.249009667
--------------------------------------------------------------------------------------

The client side doesn't show any images.

If the server on another ubuntu 16.04 machines, the client side can show 
normally.

Why the v4l2src lost frames on raspberry?