[FFmpeg-user] Obviating for webcam startup times for live webcam recording?

[Mathieu Bosi]

2018-02-05 19:40 GMT+01:00 Mathieu Bosi <mathieu.bosi at gmail.com>:

> Hi
>
> I am successfully recording videos from my webcam using ffmpeg under
> windows with the
> Direct Show source type with the following command line:
>
>   ffmpeg -f dshow -video_size 640x360 -rtbufsize 4MB -framerate 30
> -pixel_format yuyv422 -i video="Logitech BRIO" out.mp4
>
> All is working nicely, however I encountered the following problem:
> since the ffmpeg command line is launched, the webcam takes some time
> (around 2-3 seconds) to start streaming.
> I know that this is a limitation that depends on the webcam way of
> functioning / driver,
> since this will happen with any other software accessing it (e.g. Skype).
>
> The thing is that I would need video recording start to be as fast as
> possible since the command line is started.
>
> I was thinking that a possible solution would be to use a first instance
> of ffmpeg to read the webcam,
> keeping it running and continuously "streaming" it to a second ffmpeg
> instance that could then
> access the live stream of data only when needed.
> I thought that in this way webcam video recording startup delay would be
> eliminated or greatly reduced.
>
> A note: I need to record more than one video, so I would let instance 1
> always run, and only launch instance 2 when I want to record a new video.
>
>
> So, my question are the following:
> 1. is such two "ffmpeg instances" configuration possible?
> 2. if so, what is the most efficient way to stream / pipe the video data
> from instance 1 (hot webcam) to instance 2 (save to disk) with minimal
> video quality loss?
>
>
> Thanks for your help!
>
>
> Regards
>
>
> --
> Mathieu Bosi
> www.mathieubosi.com
>

This is the solution I finally adopted:

https://ffmpeg.zeranoe.com/forum/viewtopic.php?f=7&t=5473#p13207

Regards

-- 
Mathieu Bosi
www.mathieubosi.com