Autor Thema: Turning off LED diode, and "downsampling" video?  (Gelesen 5355 mal)

sssmmmddd

  • Newbie
  • *
  • Beiträge: 9
    • Profil anzeigen
Turning off LED diode, and "downsampling" video?
« am: April 08, 2010, 10:11:28 Vormittag »
Hi all,

I am using Sundtek with VLC under Ubuntu 9.10 (strangely in Kaffeine the audio does not work), and it all works fine, except I have two issues:

* When the device is first plugged in, the LED is not flashing. Then as soon as I start watching, the LED turns obviously ON. However, after I stop watching, the LED is still ON, and it remains ON even when I set the PC to suspend. Is there any way to turn off the LED using a separate software command, for example?

* There are some HD channels available, which my PC is unfortunately not powerful to decode completely - and both video and audio drop constantly. What I would like to do in this case, is maybe use some command, so I watch the video at half resolution or less (in the end, what I care for mostly is that the audio is uninterrupted). There is a "half resolution" video command in VLC, but it seems to scale the HD video *after* the full HD has been received, which just hurts performance slightly. Ideally, I'd like to instruct the device to "capture" at half the video resolution, so there is both less data to decode on the PC side and less data through USB. Are there any chances of doing this?

Thanks,
Cheers!   

Sundtek

  • Administrator
  • Hero Member
  • *****
  • Beiträge: 8357
    • Profil anzeigen
Re:Turning off LED diode, and "downsampling" video?
« Antwort #1 am: April 08, 2010, 10:28:45 Vormittag »
The LED indicates the power status of the device, when the blue led is on the device is fully powered on.

The LED will turn off after 15 seconds of inactivity (Applications accessing the DVB Stick must be closed).
Although we already received some feature requests:
* to turn off the LED manually
* to power down the device manually

we will add it to the next driver release which we will provide around mid next week (14th April).

Zitat
I am using Sundtek with VLC under Ubuntu 9.10 (strangely in Kaffeine the audio does not work), and it all works fine, except I have two issues:

This is a codec issue and related to kaffeine, our software engineers are currently working on our own player (Mac/Linux) which is dedicated for those devices. This should help to avoid any codec issues in future. You might file a bugreport for Kaffeine: http://kaffeine.kde.org/?q=bugs

We are currently investigating alternative options for HDTV channels, currently it either requires an NVidia Graphiccard or a fast PC. Lowering the resolution is not useful since the entire video is encoded in HDTV and rescaling can only be done by postprocessing and adding additional CPU power to the entire process chain. Even if you rescale it the input data is always the same, the USB Stick can handle the HDTV input data without any problem.
Failure is a good thing! I'll fix it

sssmmmddd

  • Newbie
  • *
  • Beiträge: 9
    • Profil anzeigen
Re:Turning off LED diode, and "downsampling" video?
« Antwort #2 am: April 08, 2010, 03:47:13 Nachmittag »
Hi,

we will add it to the next driver release which we will provide around mid next week (14th April).

Great! My system is not exactly stable, which is possibly why I haven't yet seen the stick turn off after 15s ... quite possible that some of my software does not close right and keeps on claiming the device. So having a command to explicitly turn it off, will save hours of troubleshooting of what could be wrong with my system :)

We are currently investigating alternative options for HDTV channels, currently it either requires an NVidia Graphiccard or a fast PC. Lowering the resolution is not useful since the entire video is encoded in HDTV and rescaling can only be done by postprocessing and adding additional CPU power to the entire process chain. Even if you rescale it the input data is always the same, the USB Stick can handle the HDTV input data without any problem.

I agree with this, which is why I think I haven't explained myself :)

Ok, I assume (but am not sure) that crudely the process goes:
* stick receives a frame of a given resolution
* stick packs the frame, sends it via USB
* PC/driver receives USB packet, retrieves data, unpacks frame
* PC then decodes frame

So, lets say, I'm receiving 400x200 video (just giving some round numbers as example), I would depict it like this:

(400x200 air) => Stick => (400x200 USB) => PC (unpack, decode: 400x200)

Say I can watch this fine, but then I try HD - lets say it is 800x400; then I would depict the process like

(800x400 air) => Stick => (800x400 USB) => PC (unpack, decode: 800x400)

and the bottleneck here is that the PC cannot unpack/decode 800x400 ( I was never implying that the USB Stick cannot handle HDTV input :) )

So, what I was hoping for, is that there would be some driver command, so I would set something like, say, 'hdlowres=1', in which the stick could possibly resample the frame to a lower resolution (say, by sending only every other pixel), and send it as such to PC; i.e.:

(800x400 air) => Stick => (400x200 USB) => PC (unpack, decode: 400x200)

in which case, the PC 'from the start' would receive a 400x200 frame, which it can handle :)

Now, I understand this is very simplified - and probably not how the actual processes occur in the stick; and of course, it depends on whether the stick itself has access to decoded pixels already - I guess it doesn't, but I just wanted to make sure...

Thanks again for the answers,
Cheers!   

Sundtek

  • Administrator
  • Hero Member
  • *****
  • Beiträge: 8357
    • Profil anzeigen
Re:Turning off LED diode, and "downsampling" video?
« Antwort #3 am: April 08, 2010, 04:16:05 Nachmittag »
Hi,

we will add it to the next driver release which we will provide around mid next week (14th April).

Great! My system is not exactly stable, which is possibly why I haven't yet seen the stick turn off after 15s ... quite possible that some of my software does not close right and keeps on claiming the device. So having a command to explicitly turn it off, will save hours of troubleshooting of what could be wrong with my system :)


you can check with

Zitat
/opt/bin/mediaclient --lc

which client is accessing the device.
 
In order to force the disconnection you can run:

Zitat
/opt/bin/mediaclient --dc [pid]
Zitat
Ok, I assume (but am not sure) that crudely the process goes:
* stick receives a frame of a given resolution
* stick packs the frame, sends it via USB
* PC/driver receives USB packet, retrieves data, unpacks frame
* PC then decodes frame


Only in case of analog TV the stick can do this. For digital TV MPEG2/4 is directly broadcasted over the air or through the cable, the stick converts this signal into a USB conform signal and the driver translates this USB Signal into a system usable format. We do not have access to the stream on videoframe level for DVB.
« Letzte Änderung: April 08, 2010, 04:22:03 Nachmittag von Sundtek »
Failure is a good thing! I'll fix it

sssmmmddd

  • Newbie
  • *
  • Beiträge: 9
    • Profil anzeigen
Re:Turning off LED diode, and "downsampling" video?
« Antwort #4 am: April 08, 2010, 07:27:09 Nachmittag »
Just wanted to say - thanks, Support, for the answer, it clarified a lot of misunderstandings I had ! :D

Cheers!