FFMPEG: audio out of sync - audio

Question

ffmpeg -rtsp_transport tcp -i "rtsp://.............." -re -stream_loop -1 -i audio.m4a -filter_complex "[0:a]highpass=f=200,lowpass=f=3000,volume=0.3[mic];[1:a]volume=0.1[mic2];[mic][mic2]amix=duration=shortest[a]" -map 0:v -map "[a]" -c:v copy -b:a 320k -c:a aac -f flv "rtmp://......."
This is my working very well script thanks to #Ilogan
But now i have a problem with an audio out of sync, i don't care about the second one, its just a file audio but the first one is from a microphone of camera IP so it should be synced with the video but now the sound from a microphone is almost 28 seconds later.
Any tips how to do it?
adelay=28000 ? - nope, that didnt help since i need to delay the video to sync this with an audio.Also tried -use_wallclock_as_timestamps 1 but it didnt help neither.
Also i used -itsoffset 28 it helped but for a while, looks like that the delay time between video and audio is rising and now its 40sec+
Whats going on?
Now i'm trying with tpad=start_duration=28
edit:
Metadata:
title : NVT
comment : From NVT
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: h264 (High), yuvj420p(pc, progressive), 1920x1080, 5 fps, 30 tbr, 90k tbn, 10 tbc
Stream #0:1: Audio: pcm_mulaw, 8000 Hz, mono, s16, 64 kb/s
Stream #0:2: Data: none
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'audio.m4a':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2mp41
title : Nature
artist :
date : 2018
encoder : Lavf58.20.100
comment :
Duration: 08:20:49.15, start: 0.000000, bitrate: 129 kb/s
Stream #1:0(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s (default)
Metadata:
handler_name : ISO Media file produced by Google Inc. Created on: 01/28/2020.
Stream mapping:
Stream #0:1 (pcm_mulaw) -> highpass
Stream #1:0 (aac) -> volume
Stream #0:0 -> #0:0 (copy)
amix -> Stream #0:1 (aac)
Press [q] to stop, [?] for help
[rtsp # 0x82e490] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
Output #0, flv, to 'rtmp://....':
Metadata:
title : NVT
comment : From NVT
encoder : Lavf58.20.100
Stream #0:0: Video: h264 (High) ([7][0][0][0] / 0x0007), yuvj420p(pc, progressive), 1920x1080, q=2-31, 5 fps, 30 tbr, 1k tbn, 90k tbc
Stream #0:1: Audio: aac (LC) ([10][0][0][0] / 0x000A), 44100 Hz, stereo, fltp, 128 kb/s (default)
Metadata:
encoder : Lavc58.35.100 aac
frame= 7 fps=0.0 q=-1.0 size= 572kB time=00:00:00.44 bitrate=10634.7kbitsframe= 13 fps= 13 q=-1.0 size= 697kB time=00:00:00.88 bitrate=6463.4kbits/frame= 25 fps= 16 q=-1.0 size= 1185kB time=00:00:01.48 bitrate=6533.1kbits/frame= 33 fps= 16 q=-1.0 size= 1390kB time=00:00:01.99 bitrate=5702.1kbits```