[General Questions and Answers] kokoko3k:
See:

# dumpsys media.audio_flinger
Clients:
pid: 893
pid: 1316
pid: 2188
Notification Clients:
pid: 311
pid: 750
pid: 893
pid: 1316
pid: 2188
pid: 2795
Global session refs:
session pid count
19 893 2
Hardware status: 0
Standby Time mSec: 3000

Output thread 0xf178d000:
Normal frame count: 1152
Last write occurred (msecs): 251498
Total writes: 1922
Delayed writes: 1
Blocked in write: no
Suspend count: 0
Sink buffer : 0xf0d46000
Mixer buffer: 0xf0adc000
Effect buffer: 0xf1712000
Fast track availMask=0xfe
I/O handle: 2
TID: 711
Standby: yes
Sample rate: 48000
HAL frame count: 1152
HAL buffer size: 4608 bytes
Channel Count: 2
Channel Mask: 0x00000003 (front-left, front-right)
Format: 0x1 (pcm16)
Frame size: 4
Pending config events: none
AudioMixer tracks: 0x00000001
FastMixer not initialized
Stream volumes in dB: 0:-5.9, 1:-inf, 2:-inf, 3:-inf, 4:-29, 5:-inf, 6:0, 7:-inf, 8:-inf, 9:-inf
Normal mixer raw underrun counters: partial=0 empty=0
1 Tracks of which 0 are active
Name Active Client Type Fmt Chn mask Session fCount S F SRate L dB R dB Server Main buf Aux Buf Flags UndFrmCnt
0 no 893 5 00000001 00000003 19 4233 S 1 44100 0 0 00016BC6 0xf0d46000 0x0 0x601 1073
2 Effect Chains
1 effects for session 0
In buffer Out buffer Active tracks:
0xf1712000 0xf1712000 0
Effect ID 13:
Session Status State Engine:
00000 000 003 0xeff103c0
Descriptor:
- UUID: 41D3C987-E6CF-11E3-A88A-11ABA5D5C51B
- TYPE: EE48CF24-9221-4095-2CB9-40FAA133111B
- apiVersion: 00020000
- flags: 0000F010 (conn. mode: insert, insert pref: last, volume mgmt: none, input mode: direct+provider, output mode: direct+provider)
- name: ViPER4Android [2.5.0.4]
- implementor: ViPER.WYF
- Input configuration:
Frames Smp rate Channels Format Buffer
01152 48000 00000003 1 (pcm16) 0xf1712000
- Output configuration:
Name Active Client Type Fmt Chn mask Session fCount S F SRate L dB R dB Server Main buf Aux Buf Flags UndFrmCnt
0 no 893 5 00000001 00000003 19 4233 S 1 44100 0 0 00016BC6 0xf0d46000 0x0 0x601 1073
2 Effect Chains
1 effects for session 0
In buffer Out buffer Active tracks:
0xf1712000 0xf1712000 0
Effect ID 13:
Session Status State Engine:
00000 000 003 0xeff103c0
Descriptor:
- UUID: 41D3C987-E6CF-11E3-A88A-11ABA5D5C51B
- TYPE: EE48CF24-9221-4095-2CB9-40FAA133111B
- apiVersion: 00020000
- flags: 0000F010 (conn. mode: insert, insert pref: last, volume mgmt: none, input mode: direct+provider, output mode: direct+provider)
- name: ViPER4Android [2.5.0.4]
- implementor: ViPER.WYF
- Input configuration:
Frames Smp rate Channels Format Buffer
01152 48000 00000003 1 (pcm16) 0xf1712000
- Output configuration:
Buffer Frames Smp rate Channels Format
0xf1712000 01152 48000 00000003 1 (pcm16)
1 Clients:
Pid Priority Ctrl Locked client server
2188 0 yes yes 0 0
1 effects for session -1000
In buffer Out buffer Active tracks:
0xf1712000 0xf1712000 0
Effect ID 12:
Session Status State Engine:
-1000 000 003 0xed939690
Descriptor:
- UUID: F1C02420-777F-11E3-981F-0800200C9A66
- TYPE: 93CC8FB0-7776-11E3-981F-0800200C9A66
- apiVersion: 00020000
- flags: 00040248 (conn. mode: insert, insert pref: first, volume mgmt: implements control, device indication: requires updates, input mode: no
t set, output mode: not set, mode indication: required)
- name: ICEpower ICEsound Algorithms
- implementor: ICEpower a/s
- Input configuration:
Frames Smp rate Channels Format Buffer
01152 48000 00000003 1 (pcm16) 0xf0d46000
- Output configuration:
Buffer Frames Smp rate Channels Format
0xf0d46000 01152 48000 00000003 1 (pcm16)
1 Clients:
Pid Priority Ctrl Locked client server
1316 0 yes yes 0 0

...in particular:

- flags: 0000F010 (conn. mode: insert, insert pref: last, volume mgmt: none, input mode: direct+provider, output mode: direct+provider)

insert pref: last

Reference here (check insertion preference)

https://source.android.com/devices/halref/audio__effect_8h_source.html