[mythtv] specification of .nuv file with rjpeg video compression ?!

[tormen at gmx.net]

Hi.

There is a problem with .nuv files that contain rjpeg compressed video:

mplayer can't play it.
Even though it can play .nuv files with divx compressed video inside!

I am trying to find out, why. So I asked on the mplayer mailinglist for 
help. And they seem really willing to help there.

So I want to ask here if there is maybe someone involved in the code 
that encodes or decodes the .nuv + rjpeg code in mythtv / mythfrontend 
and if he or she could be willing to help me to sort out the problems
that mplayer has when playing this sort of nuv files.

I recorded a short example video with mythtv 0.20.1_p13344 and put it
here: http://posern.org/test/sample.nuv

About this video I got the following answer from the mplayer 
mailinglist:
> Well, that file does not contain the quantizers used to encode it. I
> guess mythfrontend uses some default values - MPlayer unfortunately uses
> 0 as default which results only in a black/green screen.

And below is the latest answer of a guy who /seems/ to know what he is
talking about :-)

Hope on some help on this.

Whats my motivation?
Because I have (regularily) many .nuv files that fail to be 
reencoded with mythtranscode with the (mysterious) error 247:
2007-05-28 09:53:43.913 Copying Audio while transcoding Video
2007-05-28 09:55:44.658 NVR: lame error '-1'
2007-05-28 09:55:44.670 Transcode: Encountered irrecoverable error in 
NVR::WriteAudio
2007-05-28 09:55:44.671 Transcoding 
/LINKS/tv/myth/Harald_Schmidt_#_#_2007-05-10,2245.00.nuv failed
[247]

That's the reason - beside that I would love also to be able to play 
a tv recording also easily from console (with mplayer) - that I am 
interested in mencoder in the hope that his feature to simply copy the 
audio information would help me here with this buggy(?) audio 
information <<< even though mythtv can play the above video with sound 
properly.


Greetings,

tormen.

On Mon, May 28, 2007 at 10:05:16AM +0200, Reimar Döffinger wrote:
> Hello,
> On Mon, May 28, 2007 at 01:38:55AM +0200, tormen at gmx.net wrote:
> > As I don't know what a "quantizer" is, I wanted to ask:

> > So there is missing some information normaly stored in (the header? of) 
> > a .nuv file here?

> Yes, in the section that starts with "DR". That section actually even is
> in that file, but it contains only 0, so that any data in the file is
> multiplied with 0 before it gets displayed - resulting in the green
> frame. Unfortunately that does not seem to be the only problem.

> > Are the missing quantizers part of the .nuv container format or part of 
> > the RJPG video compression?

> Not sure what exactly you mean.

> > And is this information that is missing just one number (a quantizer) or
> > many numbers?

> 2 * 64 numbers.

> > And these quantizer were also not part of the nuvinfo output I appended 
> > to my first posting?
> > (like rtjpeg_quality:  170 or seektable_offset, height, width or 
> > aspect)

> No, but they probably can be derived from the quality setting, I
> currently know neither the formula nor where the appropriate place to
> put this is.

> > If you or someone could give me (short) answers on this questions
> > I would be hoping to have better chances to get this changed/fixed from 
> > the mythtv side.

> I first assumed the values are supposed to be derived from the quality
> setting to save the space for 2*64 ints in the file, but that space is
> still wasted in that file.
> You could also ask them if they happen to have a specification around...

> > I know that I can't expect anything here.

> I didn't say I wouldn't fix it, I just don't know yet exactly when and
> how.

> Greetings,
> Reimar Döffinger
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