On 20 August 2010 00:37, Niko Mikkilä <nm@xxxxxxxx> wrote: > Thu, 2010-08-19 at 20:54 +0400, Goga777 wrote: >> > Computer hardware usually cannot provide 50.000Hz, 59.940Hz or 23.976Hz >> > outputs to your TV/Monitor. This will cause some judder on display output >> > as MPEG/AVC input-stream is not synchronized to output framerate. >> >> do you mean that all nvidia vdpau cards with existing drivers from Nvidia can't provide exact 50.000Hz, >> 59.940Hz or 23.976Hz ?? > > There is no graphics card, BD/DVD player or other standalone device that > outputs those rates exactly. I don't know how much they deviate, but I'd > guess it's usually something like 0.01 % (50.005 Hz instead of 50 Hz), > as Jori said. > > However, the rate doesn't need to match exactly because the display > device is synchronized to the video signal. The rate could be 50.1 Hz or > maybe even 51 Hz and the display wouldn't mind. 50 fps video files would > play slightly faster, but there would be no need to drop video frames > because of that. > > Things are more problematic when receiving live broadcast. Then the > display and the video source (graphics card and software) needs to be > synchronized to the broadcast to avoid dropping or duplicating frames. > Set-top digital television boxes and FF DVB cards do that, but most > graphics cards/drivers can't because they aren't designed to follow an > external time source. > > Audio playback synchronation is another issue, and somewhat difficult to > handle properly on a PC where the audio chip's clock is almost always > separate from the graphics card's clock. By default, many media players > time everything according to the audio clock, and therefore they need to > drop/duplicate video frames every now and then. The other alternative is > to drop/duplicate audio frames or resample the audio completely. > > -- > > Niko > > The hardware is also running some kind of software/firmware (binary blob). I would think that the Larabee would have been the perfect choice, easier to create newer/maintaining firmware, since it is x86 based. If they made the Larabee propriety for the parts that we are interested in. Then it would also defeat the purpose of having a dynamic decoding environment. Which current hardware devices fail to do. There for the argument to have a software based solution that can do more than just one thing, not just live tv but also alternative media sources/codecs. Current hardware is good for Live TV and Recordings, software based solutions are good for dynamic media/source input, newer codecs etc, not so good at displaying it properly 100% all the time. my 2c. _______________________________________________ vdr mailing list vdr@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/vdr
