[pvrusb2] hauppage hvr-1900 on raspberry pi

[Emmanuel Touzery]

well i researched a bit more, now i'll try dvbstream and vlc streaming.

On Sun, Jun 17, 2012 at 10:48 AM, Emmanuel Touzery <etouzery at gmail.com>wrote:

> Otherwise if someone is interested, for now I still can't make DVB-T
> recording work smoothly. Ethernet was a big help but not quite enough.
>
> I've made quite some tuning, using mplayer instead of tzap+cat, and then
> strongly prioritize that mplayer process: chrt 99 with FIFO scheduling,
> nice -20, ionice -c1 (though i guess that last one doesn't make a real
> difference), and even some scheduler tuning to increase latency and
> prioritize real time processes:
>
> echo -1 > /proc/sys/kernel/sched_rt_runtime_us
> echo 40000 > /proc/sys/kernel/sched_rt_period_us
> echo 600000 >  /proc/sys/kernel/sched_latency_ns
> echo 400000 >  /proc/sys/kernel/sched_min_granularity_ns
>
> I've also tried NFS, udp and tcp, with max block size (1Mb!), 32kb and
> 64kb, but i still get cuts.
>
> I actually now get 15 minute blocks without cuts. But even only every 15
> minutes, a cut is a cut...
> i also tried overclocking the pi without big differences (i actually
> didn't try to overclock it on the latest settings but i guess it also
> wouldn't help).
>
> i'll see, i'm still not quitting but getting closer :-/
>
> emmanuel
>
>
> On Thu, Jun 7, 2012 at 10:08 PM, Felix Lighter <felix.lighter at gmail.com>wrote:
>
>> I'm glad that Ethernet helped the situation.
>> Beware USB - it's also notorious for aggressively interrupting the CPU.
>> 480Mbps USB2 comes at a high price, CPU-wise. And as you point out,
>> it's already busy capturing video.
>>
>> I would definitely suggest looking into NFS, since you should be able
>> to lighten the CPU load even further by increasing the write buffer
>> size (in the mount options). Take a look and see whether Samba also
>> offers any options for tuning network usage / bandwidth.
>>
>> Cheers,
>> FL
>>
>> On 7 June 2012 15:43, Emmanuel Touzery <etouzery at gmail.com> wrote:
>> > Hello,
>> >
>> >  Thanks for a lot for the tip. I tried quickly with a SMB share which I
>> > already had setup and... yes it seems better! Although I really can't
>> > believe it, it does seem to help. I'm glad you give me a plausible
>> > explanation with DMA though, because that's the last thing I was
>> expecting.
>> > Especially since my network is not wired and though it's plugged using
>> > ethernet on the pi, it reaches my computer through wifi.
>> >
>> >  I'll try more. I didn't try much with USB keys too because I measured a
>> > slightly lower throughput than with the SD card and I read that on the
>> pi,
>> > the throughput for USB+ethernet is shared. I figured, since USB is
>> already
>> > busy receiving the data from the video capture device, better save on
>> the
>> > SD... but apparently not.
>> >
>> >  But really I can't conclude much until I test more. The first tests
>> seems
>> > to say network>usb>sd. but even on network I've seen a skip. Though
>> it's on
>> > a non-preempt kernel and without any sort of buffering (eg flywheel or
>> > fifo), nor nice or chrt.
>> >
>> >  Anyway, it seems there's not much hope of configuring something
>> > differently on the driver or the kernel, so for now I'll focus on where
>> to
>> > save: SD, network, usb, with or without FIFO and so on. And maybe also
>> NFS
>> > vs SMB, if SMB doesn't always cut it. Definitely network appears the
>> most
>> > promessing option for now! So thanks again for the tip!
>> >
>> > emmanuel
>> >
>> > On Wed, Jun 6, 2012 at 10:27 PM, Felix Lighter <felix.lighter at gmail.com
>> >wrote:
>> >
>> >> Saving to a network share (e.g. NFS with intermediate block size)
>> >> might perform better.
>> >> The Ethernet port is likely to be much better served by the CPU's DMA
>> >> facilities than its SD interface is.
>> >>
>> >> Cheers, FL
>> >>
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