Firmware

DH_VTO3221E_Eng_P_SIP_V1.000.0000002.0.R.20210720.bin

Viatec firmware released Jul 20, 2021. May work with 2 devices, including VTO3221E, VTO6221E.

Download

Permanent copy on the Internet Archive (item page)

Hardware IDs this firmware's installer accepts (2 devices).

Where these IDs come from

hwid: the device's own hardware check list, 2 IDs
Install: the installer's device list (board families), 7 IDs, vendor Dahua (not counted: a more specific list exists)
check.img: the device's own hardware check list, 2 IDs

Read from inside the firmware (dahua package (zip variant)).

Flash layout: 14 partitions, 9 written by this firmware

From the firmware's partition table (partitionV2.txt).

Partition	Start	End	Size	Image	Filesystem	Built
U-Boot	0x200000	0x300000	1.0 MB	dhboot.bin.img	—	2021-07-20
hwid	0x300000	0x400000	1.0 MB	not written	—	—
updateflag	0x400000	0x500000	1.0 MB	not written	—	—
partition(ro)	0x500000	0x600000	1.0 MB	partition-x.cramfs.img	cramfs	2021-07-20
custom(ro)	0x600000	0x980000	3.5 MB	custom-x.squashfs.img	squashfs	2021-07-20
product(ro)	0x980000	0xd00000	3.5 MB	pd-x.squashfs.img	squashfs	2021-07-20
Kernel	0xd00000	0x1200000	5.0 MB	kernel.img	—	2021-07-20
romfs(ro)	0x1200000	0x1a00000	8.0 MB	romfs-x.squashfs.img	squashfs	2021-07-20
web(ro)	0x1a00000	0x1e00000	4.0 MB	web-x.squashfs.img	squashfs	2021-07-20
data(ro)	0x1e00000	0x2200000	4.0 MB	data-x.squashfs.img	cramfs	2021-07-20
user(ro)	0x2200000	0x3b80000	25.5 MB	user-x.squashfs.img	squashfs	2021-07-20
syslog	0x7200000	0x7600000	4.0 MB	not written	ubi	—
config	0x7600000	0x7a00000	4.0 MB	not written	yaffs2	—
backup	0x7a00000	0x7e00000	4.0 MB	not written	yaffs2	—

Other files for much of the same hardware, from any vendor.