[FFmpeg-user] Recording affected by streaming

[Jiin Joo Ong]

Hi everyone,

I’m looking for some tips on how to record a Git2 h264 feed smoothly on a Raspberry Pi without being affected by it trying to stream over long distance Wi-Fi network.

The network we are on will occasionally be bad, but we would like the recording to be perfect regardless of intermittently bad streaming quality. I’ve tried using the tee pseudo mixer as well as a real tee in my experiments:


1) Baseline: record only

ffmpeg -f v4l2 -input_format h264 -video_size 640x480 -framerate 30 -i /dev/video0 -f flv -vcodec copy -r 30 -b:v 1M -tune zerolatency -preset ultrafast /home/pi/recordonly.h264

Result: A very smooth recording of whatever the Git2 hardware pre-encoded.


2a) Turn on streaming with tee pseudo muxer

ffmpeg -f v4l2 -input_format h264 -video_size 640x480 -framerate 30 -i /dev/video0 -f tee -map 0:v -vcodec copy -r 30 -b:v 1M -tune zerolatency -preset ultrafast "[f=flv]rtmp://x.x.x.x:1935/my_url|/home/pi/pseudotee.h264 <rtmp://x.x.x.x:1935/my_url%7C/home/pi/pseudotee.h264>"

Result: pseudotee.h264 looks identically bad as the recording we made at the receiving point for the RTMP feed.


2b) Turn on streaming with pipes to use the system’s tee and 2 ffmpegs

ffmpeg -f v4l2 -input_format h264 -video_size 640x480 -framerate 30 -i /dev/video0 -f flv -vcodec copy -r 30 -b:v 1M -tune zerolatency -preset ultrafast pipe: | tee /home/pi/unixtee.h264 | ffmpeg -i pipe: rtmp://x.x.x.x:1935/my_url <rtmp://x.x.x.x:1935/my_url> 

Result: a _slightly_ better looking, but otherwise still bad recording is made.



Is there anyway for me to prioritise the creation of a good recording of the live stream over the actual stream?

Thanks
Jiin Joo