Video Rendering Approaches


1. DirectShow: old technology which started in the late 90s.
It can get the job done by constructing a graph with existing filters.
More flexibility can be achieved by customizing the rendering filters.
I used in 2010 to playback school buses surveillance video.

2. Direct3D:
This is like making a rendering filter but outside of DirectShow’s frame work, video frame as texture on a poly.
Great flexibility can be achieved, but Direct3D coding may take more time to get up to speed.
Input can be raw video video frame such as YUV420. The YUV gets copied to the texture, by the route below.
YUV -> CreateOffscreenPlainSurface.IDirect3DSurface9.D3DLOCKED_RECT.pBits -> IDirect3DTexture9.IDirect3DSurface9
I did this in 2014 in my project to render video from IP cameras.

3. GDI: for rendering GUI in the old days, not for video as it’s too slow.

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How to keep a process running after logout with bash without help from disown and nohup


Necessary and Sufficient Conditions based on my test: (AWS Ubuntu EC2)
1. redirect input and output
2. put it to background by & sign
By doing the two above, with neither disown nor nohup, my process keeps running even after logout from ssh.
However, I am not very clear why.
Example: for(( i = 0; i < 5; i++)); do sleep 2; echo $i; done t.txt 2>&1 &

HLS segmentation


Two ways to do this: server pull or video source push
Push: server runs nginx-rtmp-module, video comes in through RTMP
  Pro: all video source devices can stay behind NAT in case no control on router.
Pull: server runs ffmpeg to pull video directly from cameras through RTSP.
  Pro: no server needed on video source site, since server directly talks to cameras.
    ffmpeg is far more feature rich than nginx-rtmp-module
    rtmp-module doesn’t even have the option to organize segment into sub folders
    (think hundrdeds of thousands of .ts files).

Extra credits to ffmpeg:
Some software stays stable by keeping the feature set small.
However, not only does Ffmpeg stays stable, but it has so many features and does every single one so well.

Linux Rocks: Stability and Flexibility


It has been running day and night, without even a single hiccup, for 4 months and 9 days, and still counting.
The on-premise Linux server is loaded with our HLS streaming and recording software, either free or in-house.
The video comes from 9 IQ762W IP cameras.
This server is running Ubuntu 16.04 LTS, Mysql 5.5, Nginx 1.9, Ffmpeg and python, and some AWS client tools.

Whose servers are still running Windows then? My two most recent employers are: 3VR and Ericsson Mediaroom
3VR’s software is in C#, and they didn’t have mono as an option back then.
Ericsson Mediaroom was formerly Microsoft Mediaroom, and that’s no surprise they used Windows.