Saturday, 28 April 2012

The Media Tank Solution

Have you ever noticed how the incorrect spelling or grammar is so apparent in other blogs. But you never see them in your own!

I write it; re-write it; amend it; and then proof-read it (three times).   Subsequentially Jan or Bill point out all the obvious errors. I guess I’m just a “Big Picture” personality and sub-consciously can’t be bothered with the “little details”! And I had to re-write this paragraph twice.

Yesterday we took our Network Media Tank (NMT) out of storage and temporarily connected it between the aerial and the TV.  The NMT has two DVB-T (terrestrial) tuners.  In Australia we would use one tuner to record a program to the hard drive whilst watching another channel using the second.  The UK has a much larger choice of channels which means we will occasionally want to simultaneously record two channels.  Actually we could simultaneously record three channels as the TV also has the ability to record data to a usb thumbstick.

When we first purchased the NMT we were were recording and keeping raw data, but this starts to rapidly fill the hard drive.  To avoid this I started using Avidemux (freeware) to convert the captured programs from the broadcasted MPEG2 format to MPEG4.  By doing this the recorded data is compressed to approximately one sixth of it’s original size.  The NMT still recognises and plays the compressed AV data.  Avidemux also has the ability to cut out the advertisements.

Back in Australia Avidemux had no problem in converting the recorded data.  However there must be something different about some of the data being transmitted in the UK as occasionally Avidemux wouldn’t compress the sound.  It would just gets ignored and the end product was a silent movie!  My solution has been to first separate the captured video and sound tracks using StaxRip (more freeware).  Then recombine and compress the separate video and sound files using Avidemux.

The plan is to install the NMT in Waiouru.  In anticipation 12v and 230v power cables have already been run as well as two coaxial cables and an HDMI cable.


nb.bobcat said...

que ?

Tom and Jan said...

Which part is confusing?
1. Network Media Tank
2. MPEG2 to MPEG4
3. Avidemux
4. All of the above


Kevin said...

I'm just amazed that you can find one thing that needs recording whilst watching another... it's all repeats o my TV channels... LOL

Tom and Jan said...

Hi Kevin,

Well UK TV is all rather new to us. But it's possible we might be looking at repeats in 12 months.... :-)

nb.bobcat said...

4. !

Tom and Jan said...

The Network Media Tank is something similar to a DVD recorder/player except it's smaller and the recording is done on a hard drive. Our NMT has two TV tuners in it meaning we can either record one and watch the other or simultaneously record two separate channels.

Digital TV is broadcast in MPEG2 (Motion Picture Engineering Group standard) format (ie DVD equivalent) The data can be compress (crushed) to a newer standard (MPEG4) without adversely affecting the quality. MPEG4 files are about a sixth of the size of MPEG2. So you can get six times the data onto the hard drive.

Avidemux is a program we use to convert audio/video data from it's original format (usually MPEG2) to MPEG4 making it significantly smaller without adversely affecting the ability to replay it.

Tony Q-J said...

Hi Tom,

Because it's my trade, and because I'm a pedant, let me correct one line in your comments above. "The [MPEG2] data can be compressed to a newer standard (MPEG4) without adversely affecting the quality" should actually read "The data can be compressed to MPEG4 with an acceptable loss of quality". MPEG2 is lossy; MPEG4 is very lossy.


Tom and Jan said...

Hi Tony,

Yes, you are correct. I'm probably making the explanation too simple.