How to find out what device to use for capturing with ffmpeg?

How to find out what device to use for capturing with ffmpeg?

I'm trying to broadcast my screen and I cannot capture audio. There's one
complication however. I don't have pulseaudio, and it simply doesn't work
on my system, so installing it is out of question. Below is the command
I'm trying:
ffmpeg -f alsa -i ??? -f x11grab -s 1920x1200 -r 15 -i :0.0 \
-acodec pcm_s16le -vcodec libx264 \
-preset fast -pix_fmt yuv420p -s 1280x800 -threads 0 -f flv "$URL"
Here's the list of my audio devices:
$ aplay -L
null
Discard all samples (playback) or generate zero samples (capture)
default:CARD=PCH
HDA Intel PCH, ALC269VB Analog
Default Audio Device
sysdefault:CARD=PCH
HDA Intel PCH, ALC269VB Analog
Default Audio Device
front:CARD=PCH,DEV=0
HDA Intel PCH, ALC269VB Analog
Front speakers
surround40:CARD=PCH,DEV=0
HDA Intel PCH, ALC269VB Analog
4.0 Surround output to Front and Rear speakers
surround41:CARD=PCH,DEV=0
HDA Intel PCH, ALC269VB Analog
4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=PCH,DEV=0
HDA Intel PCH, ALC269VB Analog
5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=PCH,DEV=0
HDA Intel PCH, ALC269VB Analog
5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=PCH,DEV=0
HDA Intel PCH, ALC269VB Analog
7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=PCH,DEV=0
HDA Intel PCH, ALC269VB Digital
IEC958 (S/PDIF) Digital Audio Output
hdmi:CARD=NVidia,DEV=0
HDA NVidia, HDMI 0
HDMI Audio Output
hdmi:CARD=NVidia,DEV=1
HDA NVidia, HDMI 0
HDMI Audio Output
hdmi:CARD=NVidia,DEV=2
HDA NVidia, HDMI 0
HDMI Audio Output
hdmi:CARD=NVidia,DEV=3
HDA NVidia, HDMI 0
HDMI Audio Output
I know that ??? should be something like hw:X,Y, but maybe it can be
something else. I can't find the corresponding entry in the man page.
As an aside, it would be great if you can suggest another audio codec. I
can't find what are the options, and this particular one isn't compatible
with FLV because of too high bitrate.