Processing text in bash - extracting the volume of a program from pactl sink-inputs output

Looking for a way to extract the volume from

pactl list sink-inputs

Output example:

Sink Input #67
        Driver: protocol-native.c
        Owner Module: 12
        Client: 32
        Sink: 0
        Sample Specification: s16le 2ch 44100Hz
        Channel Map: front-left,front-right
        Format: pcm, format.sample_format = "\"s16le\""  format.channels = "2"  format.rate = "44100"  format.channel_map = "\"front-left,front-right\""
        Corked: no
        Mute: no
        Volume: front-left: 19661 /  30% / -31.37 dB,   front-right: 19661 /  30% / -31.37 dB
                balance 0.00
        Buffer Latency: 100544 usec
        Sink Latency: 58938 usec
        Resample method: n/a
        Properties:
                media.name = "'Alerion' by 'Asking Alexandria'"
                application.name = "Clementine"
                native-protocol.peer = "UNIX socket client"
                native-protocol.version = "32"
                media.role = "music"
                application.process.id = "16924"
                application.process.user = "gray"
                application.process.host = "gray-kubuntu"
                application.process.binary = "clementine"
                application.language = "en_US.UTF-8"
                window.x11.display = ":0"
                application.process.machine_id = "54f542f950a5492c9c335804e1418e5c"
                application.process.session_id = "3"
                application.icon_name = "clementine"
                module-stream-restore.id = "sink-input-by-media-role:music"
                media.title = "Alerion"
                media.artist = "Asking Alexandria"

I want to extract the

from the line

 Volume: front-left: 19661 /  30% / -31.37 dB,   front-right: 19661 /  30% / -31.37 dB

Note: There may be multiple sink inputs, and I need to extract the volume only from Sink Input #67

Thanks

P.S. Need this for a script of mine which should increase or decrease the volume of my music player. I'm completely new to both linux and bash so I couldn't figure a way to resolve the problem.

Edit: My awk version

gray@gray-kubuntu:~$ awk -W version
mawk 1.3.3 Nov 1996, Copyright (C) Michael D. Brennan

compiled limits:
max NF             32767
sprintf buffer      2040

Solution

Since you are pretty new to use standard text processing tools, I will provide an answer with a detailed explanation. Feel free to use it for future.

Am basing this answer using the GNU Awk I have installed which should likely also work in mawk installed in your system.

pactl list sink-inputs | \
    mawk '/Sink Input #67/{f=1; next} f && /Volume:/{ n=split($0,matchGroup,"/"); val=matchGroup[2]; gsub(/^[[:space:]]+/,"",val); gsub(/%/,"",val); print val; f=0}'

Awk processes one line at a time which is based on a /pattern/{action1; action2} syntax. In our case though, we match the line /Sink Input #67/ and enable a flag(f) to mark the next occurrence of Volume: string in the lines below. Without the flag set it could match the instances for other sink inputs.

So once we match the line, we split the line using the de-limiter / and get the second matched element which is stored in the array(matchGroup). Then we use the gsub() calls twice once, to replace the leading white-spaces and other to remove the % sign after the number.