Is anybody getting good DVB-T2 results on Rapsberry Pi 2?

Richard McBride

I've used TVH with the PCTV 290e DVB-T2 (HD) tuner without problems on a number of systems, including an ageing dual-core HP laptop running Kubuntu 15.10.

On the Pi 2, although everything works, I get frequent video glitches (every few minutes or more). Mostly, there is massive pixellation lasting a couple of seconds, or the lower third of the screen turns green momentarily. I'm not getting these problems on the SD tuners.

I'm using separate 2A power supplies for the Pi and a powered hub, with the latter powering the tuner, and I don't get any low-voltage warnings.

The video artefacts seem to coincide with Continuity Counter Errors on the H.264 and the AAC streams, (though mainly the H.264). Over the space of 5 minutes, I can see roughly 140 CC Errors on the H.264 stream, and 10 on the AAC stream.

I've tried both OSMC and OpenElec, (latest versions of each), and both give similar problems, though OSMC seems to give more errors than OpenElec.

In contrast, using TVH with Kubuntu on the HP notebook gives very few errors, and only very occasional video glitches.

I'm running TVH 3.9.27. On Ubuntu I'm running TVH 4.1. (These just happen to be the versions in the repositories).

I suspect that the problem may be due to the DVB-T2 tuner driver software, (which, for the PCTV 290e, is in the kernel). Either that, or the Pi just can't cope with the HD stream rate?

Any help or advice would be greatly appreciated.

mpmc

The Raspberry Pi shares a single bus between all usb devices (this includes Ethernet).

USB Bus 0 -> USB Port 1, 2, 3, 4, Ethernet.

Where as on a normal machine it's more like..


USB Bus 0 -> USB Port 1, 2
USB Bus 1 -> USB Port 1, 2
Ethernet

Because the RPI only has one bus anything connected via USB has to share it (overheads too). Many tuners; the 290e included hate sharing USB buses however it'll cope and as long as it thinks it has all available bandwidth it'll send the stream.

The problem comes when other usb devices want a piece of that bus bandwidth.. It's a tug of war between everything connected via USB and they all want the biggest slice..

It doesn't help that the Pi's usb driver isn't very good and the 290e driver assumes that it has full reign over the bus it's using.

I have used the 290e on my Pis (1 & 2) in the past but because of the bandwidth restrictions it's not very good for streaming..

This is one of the reasons I bought a Banana Pi M1 (with proper 1000Mb Ethernet and 4 Buses), I think I paid about £23 for it.
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Richard McBride

Ahah - that would explain my problems. All is well until another process grabs some bandwidth on the bus, then packets start getting lost from the TV stream.
Thanks for the very clear explanation Mark!