[mythtvnz] nuvexport of HD recordings

[Tony Sauri]

On Mon, 15 Feb 2010 12:01, Robin Gilks wrote:
> Has anyone managed to get nuvexport to understand H264 recordings? I get
> as far as being told there is no profile for H264 but no clue is given as
> to where the profile is supposed to exist (MythTV?, novexport?, ffmpeg?).
>
> Cheers
Sorry for the late response  -  I am on holiday and have been out of touch for 
a few days.

I feel I can perhaps provide a little guidance as I have cracked some of the 
problems associated with lower spec display hardware.

I blithly thought I would be able to enter the DVB-T world with just the 
addition of a Hauppauge Bova-T 500 card.  :-)

My display platform is an IBM Thinkpad T23 1.13GHz as the Myth frontend and a 
rather ancient 19in Sony CRT TV with 4:3 format.  The Thinkpad screen is 
resolution 1024x768.

And then the problem solving started. 

Very early on I decided that nuvexport is too constrained by USA formats to be 
used effectively in NZ and I set about writing a Userjob in perl to do the 
transcoding with ffmpeg.

I set the target quality I was  hoping to achieve to be as close to DVD 
quality as possible and in general I have been pleased with the result.

The transcoding takes place on a P4 3GHZ processor with 1GB ram. For lower 
spec files it achieves nearly 25 fps transcoding while for TVOne and TV2 
transcode rates average 16fps. TV3 are slower still but I dont have a good 
rate to give you as I normally record from TV3+1. 

I have been toying for sometime with writing up a howto and offering it to the 
group.

Tomorrow I will write a more detailed list of the problems I encountered and 
what I did to overcome them.

In the meantime a short list of the problems I worked on, off the top of my 
head, includes:

- audio/video sync
- decimation of TVOne and TV2 frame rates
- interlacing issues with TV3
- interface with the commercial flagging system
- odd timestamps especially on TVNZ6 that I do not fully understand that
  sometimes cause recordings to be displaced in time by up to 15 mins. (I may
  need to expand on this a bit to properly explain what I mean).

Regards

Tony Sauri