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dhav2mkv(1) DHAV video to MKV format converter dhav2mkv(1)

NAME

dhav2mkv - DHAV video to MKV format converter

SYNOPSIS

dhav2mkv [OPTION]

DESCRIPTION

dhav2mkv is a standalone tool which converts DHAV(H.264) video to MKV(H.264) video.

dhav2mkv only operates at media container level, thus the H.264 data is exactly as provided by the DVR (with all its bugs).

dhav2mkv does not support specifying a channel number. It assumes the stream holds a single channel, instead of a theoretically possible 'n' multiplexed channel stream. The reason that option support was dropped is that some DVRs generate DHAV streams with incorrect channel number such way that two or more channels collide with the same channel number, what makes impossible to differentiate one from another. Also there's the fact that DHAV multi-channel multiplexing is not used in practice.

This tool is part of the TaniDVR project.

OPTIONS

<input DHAV file> (default: empty -- uses stdin).
<output MKV file> (default: empty -- uses stdout).
(default: not enabled). If defined, assumes NTSC field frequency to be 60Hz, instead of the typical 59.94Hz. Some cameras do generate exact 60Hz video. This switch does NOT affect PAL video.
0 - No correction will be performed to the buggy DHAV stream timestamps. 1 - Perform timestamp correction (default).
Prints help message and exit.

USE CASES

•
To convert already-existing DHAV files to MKV. Those files may be tanidvr-generated or generated by the software included with the DVR itself (due to legacy, or by choice).

DHAV files are only (currently) playable with the software included with the DVR, while MKV is a modern, open and commonly supported container format. Using a standard container also allows the video to be recompressed for better storage usage.

•
To create a video hub (a video repeater), propagating DHAV media which, at the end-point, is converted to MKV.

The DVR itself supports a very limited number of simultaneous connections (usually slighty more than hardware channels). Also, near the maximum active connections the DVR tends to be even more unstable. Direct connections to the DVR should be kept to essencial minimum.

dhav2mkv allows the conversion of ongoing DHAV video (doing that with MKV is not viable for technical reasons). Any stream starting point (down to byte granularity) is acceptable. Also, temporary source interruption with lost/corrupted data suffers automatic resync (what is also done by 'tanidvr', when outputting MKV data).

A simple media hub may be implemented with existing complementary software such as ncat (from nmap project) with its '--broker' option.

•
For Digital Forensics. Some police forces already use dhav2mkv for last-step recovering of video evidence from apprehended DVRs.

EXAMPLES

•
Convert an existing DHAV file to MKV.



              dhav2mkv -i MyVideo.dhav -o MyVideo.mkv
•
Using dhav2mkv instead of tanidvr's internal routines. NOTE: NOT NECESSARY in practice since tanidvr can output MKV directly. It is shown only for didactic purposes.



              tanidvr -n 0 -m 1 -t 192.168.0.12 -u admin -w secret1234 -c 2 | dhav2mkv > channel_2_video.mkv
•
Simple media server and some clients. NOTE: INSECURE. NOT to be implemented as-is. It is shown only for didactic purposes.



              (server at 192.168.20.1)


              tanidvr -n 0 -m 1 -t 192.168.0.12 -u admin -w secret1234 -c 5 | ncat --broker -l 192.168.20.1 2000


              (clients ; same/other host)


              ncat --recv-only 192.168.20.1 2000 | dhav2mkv | mplayer -cache 32 -


              ncat --recv-only 192.168.20.1 2000 | dhav2mkv > channel_5_realtime_backup.mkv


              ncat --recv-only 192.168.20.1 2000 > channel_5_realtime_backup.dhav

AUTHOR

dhav2mkv was written by Daniel Mealha Cabrita <dancab@gmx.net>.

This manual page was written by Marcos Talau <marcos@talau.info> for the Debian project (but may be used by others).

18 Aug 2022 dhav2mkv-1.4.1