8.1. Avermedia DVB-T on BT878 Release Notes¶
February 14th 2006
Note
Several other Avermedia devices are supported. For a more broader and updated content about that, please check:
8.1.1. The Avermedia DVB-T¶
The Avermedia DVB-T is a budget PCI DVB card. It has 3 inputs:
RF Tuner Input
Composite Video Input (RCA Jack)
SVIDEO Input (Mini-DIN)
The RF Tuner Input is the input to the tuner module of the card. The Tuner is otherwise known as the "Frontend" . The Frontend of the Avermedia DVB-T is a Microtune 7202D. A timely post to the linux-dvb mailing list ascertained that the Microtune 7202D is supported by the sp887x driver which is found in the dvb-hw CVS module.
The DVB-T card is based around the BT878 chip which is a very common multimedia bridge and often found on Analogue TV cards. There is no on-board MPEG2 decoder, which means that all MPEG2 decoding must be done in software, or if you have one, on an MPEG2 hardware decoding card or chipset.
8.1.2. Getting the card going¶
At this stage, it has not been able to ascertain the functionality of the remaining device nodes in respect of the Avermedia DVBT. However, full functionality in respect of tuning, receiving and supplying the MPEG2 data stream is possible with the currently available versions of the driver. It may be possible that additional functionality is available from the card (i.e. viewing the additional analogue inputs that the card presents), but this has not been tested yet. If I get around to this, I'll update the document with whatever I find.
To power up the card, load the following modules in the following order:
modprobe bttv (normally loaded automatically)
modprobe dvb-bt8xx (or place dvb-bt8xx in /etc/modules)
Insertion of these modules into the running kernel will activate the appropriate DVB device nodes. It is then possible to start accessing the card with utilities such as scan, tzap, dvbstream etc.
The frontend module sp887x.o, requires an external firmware. Please use the command "get_dvb_firmware sp887x" to download it. Then copy it to /usr/lib/hotplug/firmware or /lib/firmware/ (depending on configuration of firmware hotplug).
8.1.3. Known Limitations¶
At present I can say with confidence that the frontend tunes via /dev/dvb/adapter{x}/frontend0 and supplies an MPEG2 stream via /dev/dvb/adapter{x}/dvr0. I have not tested the functionality of any other part of the card yet. I will do so over time and update this document.
There are some limitations in the i2c layer due to a returned error message inconsistency. Although this generates errors in dmesg and the system logs, it does not appear to affect the ability of the frontend to function correctly.
8.1.4. Further Update¶
dvbstream and VideoLAN Client on windows works a treat with DVB, in fact this is currently serving as my main way of viewing DVB-T at the moment. Additionally, VLC is happily decoding HDTV signals, although the PC is dropping the odd frame here and there - I assume due to processing capability - as all the decoding is being done under windows in software.
Many thanks to Nigel Pearson for the updates to this document since the recent revision of the driver.