Help with Modifying the Firmware of my HD-TVL 8CH Hikvision

Being fully aware that the HD-TVL HikVision based (actually KT&C TVL) 8 CH DVR that I have only records audio at 64 kbps at a sample rate of 8,000 hz utilizing the G.711 mulaw PCM wave codec (!! why all CCTV manufacturers uses this ancient codec from the 1970's when there are better and even freeware open source OGG compressed audio codec that can produce a much more better quality audio using less space than that crappy G.711 codec)

I have decided to add my DVR one extra function: be my cable box's DVR so that I can have DVR functionality on my TV without having to subscribe to my cable provider's DVR package and when I am on the go, I can leave my cable box on and tuned to the channel I want to record so that when I come back I simply fire up iVMS and replay the recorded show that I otherwise would have missed.

I connected my cable box RCA video and audio output to my HikVision HD-TVL DVR CH1 and audio input and configured the DVR to record on CH1 at 704x480 30 FPS at 3,000 mbps for the best quality possible and made sure the colors matched exactly to what I saw on TV so that the picture quality can be indistinguishable (except for the HD to D1 downscale of course) at this setting I am using up 30 GB per day on the quota (partition) which is fine with me as I dont need 30 days of recordings of my cable box.

As for audio, its some what acceptable when you are recording a show that only has voice as the G.711 mulaw wave PCM is optimized to record only at human voice frequency response range but not fine when there is music involved as the resultant recordings sounds like if you are listening to music from an AM radio station, a complete disregard to higher frequencies.

So, what I would like to do is modify my HiKVision firmware (digicap.dav) to change the codec/bitrate and sample rate so that the quality of the audio on CH1 can be much greater, so I downloaded the HikTools firmware extractor which gave me one file:

* cramfs.img (a hard drive image with a linux file system)

I mounted this compressed image on my linux system which revealed a bunch of compressed files that I also extracted but was unable to find the configuration file responsible for audio to edit.

I will appreciate any information and tools that can assist me at accomplishing the goal of improving the audio quality.

Edit:

I would like to add that its not illegal to treat your CCTV DVR as your TV's DVR if you only use the recording for your own personal use, no copyright infringement is being done and also its not illegal to modify the firmware of a device that you personally own and personally will be using as its part of fair use and you can do what ever you want with the device you paid for, so I find myself well within my rights to wanting to modify my DVR's codec to improve the audio quality.