Am 20.04.2012 23:58, schrieb Roland Tapken:
What is cPlayer? As cTransfer implements both cReceiver and cTransfer I thought about it as some kind of frontend abstraction (FF-output, xine, streamdev-server). But it seems that cPlayer directly acts on cDevice, and that doesn't make sense to me at the moment.
Furthermore, I'm still not quote sure where all these components where attached to each other.
A cDevice can be both, input device and output device. A cReceiver can generally receive stream data like video, audio, subtitles, teletext, EPG, and so on, from a device. A cPlayer provides video/audio data for replay and feeds it into the output device. A cControl acts as the controlling interface of a cPlayer. It can handle keyboard and OSD interaction for a cPlayer device. A cTransfer is a cReceiver and a cPlayer, and just pumps data between these two.
One thing to understand is that a cDevice can be stream source and output device at the same time. Generally, if you switch to a channel, the output device will be asked to show a specific channel. Only if the device itself is unable to do this on its own, a different device will provide the video stream, and a cTransfer is created to transport all the data from the receiving to the output device. 'Full Featured' devices can handle all of this internally. TT-6400 cards, for example, even continue to display live TV while the computer is rebooting.
The general way to switch to a channel is:
- cDevice::PrimaryDevice()->SwitchChannel(channel, LiveView) Instruct the primary device to switch to a channel
- cDevice::SetChannel(Channel, LiveView) Actually handles the switch
- cDevice::GetDevice(Channel, Priority, LiveView, Query) Picks the device that will be receiving. Tries hard to prefer the primary device (output device) as source device too.
If receiving device is an other than the output device, a transfer control / transfer device is created to link them.
One more thing to be aware of: Old non-HD FF cards can only either receive or directly display a video stream. If you watch and record a stream, the recording will usually be on a different device, so two devices will tune to that channel. If there is no other device, and both need to use the same receiving device, then live viewing has to be done using transfer mode. (might break on high bandwidth channels.) I'm not completely sure where in the code this is handled, though. AFAIK the TT6400 cards technically can record and display at the same time, but I'm also not sure whether this is already implemented or still handled the 'old' way.
Cheers,
Udo