On Friday 29 June 2012 08:03:16 Antti Palosaari wrote: > On 06/29/2012 07:32 AM, Mauro Carvalho Chehab wrote: > > Em 27-06-2012 21:33, Antti Palosaari escreveu: > >> SDR - Softaware Defined Radio support DVB API > >> -------------------------------------------------- > >> * > >> http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructu > >> re/44461 * there is existing devices that are SDR (RTL2832U "rtl-sdr") > >> * SDR is quite near what is digital TV streaming > >> * study what is needed > >> * new delivery system for frontend API called SDR? > >> * some core changes needed, like status (is locked etc) > >> * how about demuxer? > >> * stream conversion, inside Kernel? > >> * what are new parameters needed for DVB API? > > > > Let's not mix APIs: the radio control should use the V4L2 API, as this > > is not DVB. The V4L2 API has already everything needed for radio. The > > only missing part ther is the audio stream. However, there are a few > > drivers that provide audio via the radio device node, using > > read()/poll() syscalls, like pvrusb. On this specific driver, audio > > comes through a MPEG stream. As SDR provides audio on a different > > format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD to > > set/retrieve the type of audio stream, for SDR, but maybe it better to > > just add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to > > indicate that the audio will come though the radio node and if the > > format is MPEG or SDR. > SDR is not a radio in mean of V4L2 analog audio radios. SDR can receive > all kind of signals, analog audio, analog television, digital radio, > digital television, cellular phones, etc. You can even receive DVB-T, > but hardware I have is not capable to receive such wide stream. > > That chip supports natively DVB-T TS but change be switched to SDR mode. > Is it even possible to switch from DVB API (DVB-T delivery system) to > V4L2 API at runtime? It could be possible that neither the DVB-API nor the V4L2 API is the right user-interface for such devices. The output of such devices is the acquisition of raw (digitalized) data of a signal and here signal is meant in the sense of anything which can be digitalized (e.g.: sensors, tuners, ADCs). Such device will surely be have a device-specific (user-space?) library to do the post/pre-processing before putting this data into a generic format. That said, IMO, the rtl-sdr driver should sit on the DVB-API. Maybe V4L2 provides a device-specific control path (to configure the hardware) if not somewhere else, or something new needs to be created. regards, -- Patrick. Kernel Labs Inc. http://www.kernellabs.com/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
