[FFmpeg-user] Can't combine 2 pulse input streams in screencast

[Andrew Stevanus]

Hi. I'm trying to record a screencast with ffmpeg and record my pc audio,
and my microphone. Recording only one stream works fine, but when I try to
record with two pulse inputs, I get no audio in the resulting video (I
changed one of the pulse inputs with pavucontrol to use the pc audio instead
of the microphone). Here's the command that I use:

ffmpeg -f x11grab -r 15 -s 1366x768 -i :0.0 -f alsa -ac 2 -i pulse -f alsa
-ac 1 -i pulse -vcodec libx264 -acodec pcm_s16le -vpre lossless_ultrafast
-threads 2 output.mp4

I should also say that whenever I use the input hw:0,0 or something similar,
when I play back the resulting video, the audio seems to get gradually out
of sync. Can anyone help?