Theo Verelst Local Diary Page 89

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Dec 15, 22:33, 2009

Flat tire on station wagon with tapes. ("Never underestimate the bandwidth of a station wagon full of tapes hurling down the highway" Andrew S. Tanenbaum)

Multiple sat and TV channels and HD sat simultaneous on multiple screens on one computer

It eats between 130 and 190 watts, is years old, lost its windows partition working good (I didn´t repair it to do more than safe starts), has a sat and cable connection, a new 80 euros graphics card, now runs almost only Linux RedHat Fedora 10/64, and rocks!

These are screendumps from two screens who work simultaneous on the one computer, showing in this case 2 TV channels (IIRC XV and OpenGL screen drivers and software deinterlace) and a High Definition sat channel, using VDPAU decoding and h264 rendering (on a 1680x1050 screen and a 1920x1200 pixels screen):

Those 3 windows look banded because of the standard screen save program acting on a live moving picture: the 3 windows look all great, and while this is about the maximum (I could add another (standard definition) sat channel, but that would make images jerky or motions not so good) this all runs smooth.

Even more fun, the below live screen dump of screen 2 shows that all 3 programs each generate 4 channel surround sound, which are all mixed together using qjackctl to hear 3 surrounds of pretty good quality mixed together!

Biking for Power !

A test house on the BBC-HD which is completely run on dozens of people padling bikes to generate electricity. I though they only did that in the war, for lights..

14 100 watts equivalent bikers for the washing machine, if I recall correctly, brrrr...

Another HD channel

And get it right: I´m not talking about jerky and error filled, blocky 3 frames per second of frame impressions here, but fully functional and smashing looking directly streaming HD, where the processor cores never reach 100% workload, and the main rendering and stream decoding work is each done by the capable and high quality VDPAU graphics card (hardware) acceleration facilities in my self-compiled mplayer. I´m gratefull to NVidia they did better than purevideo in a way in a Free and Open Source usable way (even though it is only the interface being open source), and that they made those facilities very well available!

So can this compare with BluRay, Theo ? "Yes and not completely", not so good blurays, even on a good player (I use a Sony S550 on a Full HD screen of good quality in most senses and an excellent Mistubishi DLP 720p beamer with fairly good pro grade screen) at times don´t make it to the viewing pleasure of some of the HD I saw and the bbc and itv, but good blurays, preferably like using avc coding with 25 to over 30 mega bits per second bandwidth can come much more alive. Also, a well made DTS surround sound track or lets say (and hope for more) 48kS/s 24 bit surround PCM sound track on a good bluray is absolutely no comparison with the few hundred kilobit/sec mp4 or mp2 audio tracks on the sat channels, sorry to say, but that doesn´t mean a good ac audio track isn´t lok enough to listen to, especially if they are actual surround tracks (not surround decodable), I listened to the 1 1/2 hour Eric Clapton / Steve Winwood concert the other day (and really mplayer can easily remain on and playing that long without hicking up or overheating the machine or so) and thought I didn´t use much volume (it was late at night) it sounded certainly good enough to be enjoyable. But again, a well made bluray has so much more sound bandwidth/bits, that is no good comparison, especially on my big audio system.

Since I don´t use a bluray computer player (or HD dvd) it has an advantage to use the sat hd: there are more control options like gamma, contrast, colour space, etc, although the Sony has possibilities, too. Adjusting the VDPau filtering and some of those xan make or break at sat viewing!

On a notebook I can view channels transported over a local network:

I tried playing the ITV HD recording I made, but the Nvidia-quadro card in the still fairly fast notebook is one generation before VDPAU, which is really needed for full resolution 1080 HD. It does have officially bought PureVideo for MPEG-2, also for HD, so I could convert the mp4-h264 from the sat recording of the ITV (BBC HD is recordable, but I need a program sctream to transport stream converter to record it efficiently) to mpeg2 usinf ffmpeg, which even for some part at least can us vdpau acceleration, and then watch actual broadcast HD (if I´m not mistaking it is even about 12 megabits per second from the ITVHD channel, which is almost light bluray bandwidth) on the Full HD notebook.

I just tried to crosscode the itvhd from h264 to mpg-2 transport stream, and it´s a success, the transcoded stream plays on Purevideo on the HD notebook in full HD!

$ ffmpeg  -i gori1.mp4 -b 25000k -f mpegts -acodec copy gori1t.mpg

Free to Air to ffmpeg (about 12 frames sec, but I didn´t check if I used VDPau, which is compiled in) over the network to the notebook, recordable on the local disk or and external drive, and playable in really the quality as shown, even without processing or adjustments (which it can do, too).

Gadgets ?

Sounds like great fun