[FFmpeg-user] Playing an uncompressed raw interlaced RTP video stream

[PaulYurt]

Are you certain the. camera output is interlaced? HD720 is typically progressive. 

If you decode progressive as interlaced you would get two very similar images. 

Paul Yurt

On Sep 26, 2018, at 8:15 AM, villastar at yahoo.com.au <villastar-at-yahoo.com.au at ffmpeg.org> wrote:

Hi, 

I am unable to get ffplay to play back a raw uncompressed interlaced
video from an RTP stream, coming from a camera feed. The camera
broadcasts the SDP using SAP, which I have been able to extract into
a local file. The contents of the SDP:

  v=0
  o=- 340496 340496 IN IP4 192.168.204.40
  s=Camera 2
  c=IN IP4 239.192.1.40/15
  t=0 0
  m=video 5004 RTP/AVP 97
  a=rtpmap:97 raw/90000
  a=fmtp:97 sampling=YCbCr-4:2:2; width=720; height=576; depth=8; colorimetry=BT601-5; interlace
  a=framerate:25

I am using the following command to play it back with ffplay:

  ffplay -protocol_whitelist file,rtp,udp -strict -2  -f sdp \
    camera2.sdp

This resulting image showed two almost identical images laid out
vertically. In order to show the results I am getting, I have also
recorded a small sample with the following:

  ffmpeg -protocol_whitelist file,rtp,udp -strict -2 -f sdp -i \
    camera2.sdp -t 5 -vf "scale=240x192,idet" camera2_sample.mp4

Note that I applied the scaling only to keep the file size small - the
resulting mp4 file is close to what I was seeing in ffplay. The file 
has been uploaded to my Dropbox at:

  https://www.dropbox.com/s/6kgfsie7rgfnoe7/camera2_sample.mp4?dl=0

The tail end of the output from FFmpeg at the end of the recording, 
including the output from idet:

  video:171kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 2.121141%
  [Parsed_idet_1 @ 000001d6ff69f4c0] Repeated Fields: Neither:  217 Top:    0 Bottom:    0
  [Parsed_idet_1 @ 000001d6ff69f4c0] Single frame detection: TFF:    0 BFF:    0 Progressive:  217 Undetermined:    0
  [Parsed_idet_1 @ 000001d6ff69f4c0] Multi frame detection: TFF:    0 BFF:    0 Progressive:  217 Undetermined:    0
  [libx264 @ 000001d680000500] frame I:2    Avg QP:18.69  size:  1068
  [libx264 @ 000001d680000500] frame P:127  Avg QP:28.83  size:  750
  [libx264 @ 000001d680000500] frame B:121  Avg QP:30.57  size:  638
  [libx264 @ 000001d680000500] consecutive B-frames: 10.0% 76.0%  1.2% 12.8%
  [libx264 @ 000001d680000500] mb I  I16..4: 77.2%  1.7% 21.1%
  [libx264 @ 000001d680000500] mb P  I16..4:  2.6%  6.1%  2.8%  P16..4: 13.2%  6.0%  2.8%  0.0%  0.0%    skip:66.5%
  [libx264 @ 000001d680000500] mb B  I16..4: 28.9%  2.5%  4.3%  B16..8:  7.2%  2.6%  0.6%  direct: 1.6%  skip:52.3%  L0:22.3% L1:76.0% BI: 1.7%
  [libx264 @ 000001d680000500] 8x8 transform intra:18.1% inter:34.7%
  [libx264 @ 000001d680000500] coded y,uvDC,uvAC intra: 18.1% 21.9% 11.9% inter: 8.7% 10.7% 2.7%
  [libx264 @ 000001d680000500] i16 v,h,dc,p: 69% 29%  1%  0%
  [libx264 @ 000001d680000500] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  1% 29% 67%  0%  1%  1%  1%  0%  1%
  [libx264 @ 000001d680000500] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu:  7% 46% 21%  4%  4%  3%  5%  3%  5%
  [libx264 @ 000001d680000500] i8c dc,h,v,p: 66% 31%  1%  1%
  [libx264 @ 000001d680000500] Weighted P-Frames: Y:0.0% UV:0.0%
  [libx264 @ 000001d680000500] ref P L0: 45.1% 14.7% 31.6%  8.6%
  [libx264 @ 000001d680000500] ref B L0: 57.7% 42.3%
  [libx264 @ 000001d680000500] kb/s:279.35

I was suspecting that FFmpeg was not treating the interlacing 
correctly. Is there an option that I should be specifying? I have 
tried playing back with the yadif and tinterlace with similar 
results. The commands I used were:

  ffplay -protocol_whitelist file,rtp,udp -strict -2  -vf yadif=mode=1 \
    -f sdp camera2.sdp

and

  ffplay -protocol_whitelist file,rtp,udp -strict -2 -vf tinterlace=6 \
    -f sdp camera.sdp
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