Recording the BATC streamer

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You can record a BATC streamer channel on your local PC using ffmpeg.

First you need to install ffmpeg - details elsewhere on this forum.

The basic command is:

ffmpeg -i rtmp://<streamname> -c:v copy -c:a copy -f mp4 recording.mp4

You can also record on a Portsdown. ffmpeg is already installed, so you just need to use the command:

rpidatv/bin/ffmpeg  -itsoffset 00:00:1.0 -i rtmp://<streamname> -c:v copy -c:a copy -f mp4 recording.mp4

You will find "recording.mp4" in the directory that you called the command from. Note - adjust the itsoffset number (final digits are seconds) for best lipsync. The value above seems to work perfectly on a Raspberry Pi 3.

On a Raspberry Pi 4 the following (long) command line was required. Note that the streamname is entered twice, once for the audio on stream 0 which is delayed by itsoffset (1.5 seconds) and again for the non-delayed video from stream 1. itsoffset can be adjusted as required.

rpidatv/bin/ffmpeg -i rtmp://<streamname>  -itsoffset 00:00:1.5 -i rtmp://<streamname> -map 1:v -map 0:a -c:v copy -c:a copy -f mp4 recording.mp4

If you are doing an important recording, test with exactly the same configuration (streaming kit and recorder) beforehand and adjust the settings to get them right.