[mythtv-users] CPU usage during Playback of content from HD-PVR

John P Poet jppoet at gmail.com
Wed Aug 13 17:55:40 UTC 2008


On Wed, Aug 13, 2008 at 10:33 AM, Brad DerManouelian
<myth at dermanouelian.com> wrote:
> On Aug 13, 2008, at 9:21 AM, Robert McNamara wrote:
>
>> Hmm, dunno why the list truncated my last message.  Last bit was...
>>
>> From experience, and speaking as someone who has been working with
>> the HD-PVR and the recordings made by it from the very earliest
>> days, anything less than that is going to have trouble at the
>> maximum capture bitrate.  This has been the experience across the
>> board of those of us working with the HD-PVR in linux.  John or
>> Janne may be able to add their voices to this discussion, but as
>> we've all being experiencing the same, and have seen the same in
>> dealing with most of the HD-PVR users in linux thus fair, I think
>> it's fair to trust our experience.  It's tough to let go of the
>> notion that resolution and bitrate are the primary factors in
>> playback ease, as this has been generally true for a long time.  The
>> HD-PVR, however, is a great illustrator of the fact that with modern
>> codecs, encoding options have just as much, if not far more bearing
>> on playability.
>
> I guess the point of this thread is what speed processor do I need to
> upgrade to in order to get playback of 720p content recorded from my
> HD-PVR. Frankly, I'm about ready to put it on ebay since using the
> damned thing means I have to get rid of every single frontend I have
> along with using an unstable version of MythTV. No fun - especially
> since I can't even get mine to work right now in Windows, let alone
> Linux. I think I have a defective unit. Waiting to hear back from
> support after trying their suggestions. I'm really sorry I bought it.

It really depends on the bitrate at which you record.  Latest SVN
supports VBR with the HD-PVR.  With VBR the "effective" bitrate is
lowered substantially, meaning you can get by with a lesser CPU.

With CBR, I can playback the highest possible bitrate with my 3.0Ghz
E8400.  However, I cannot play it back without stuttering if
TIMESTRETCH is enabled.  If I want to enable TIMESTRETCH 1.3x, I must
keep the bitrate down around 7mbit.

With VBR, I can set both sliders to the MAX, and can still turn on
TIMESTRETCH up to 1.3x with no stuttering for the majority of the
show.  For some periods in the show, it will stutter, if there is
enough action to cause the bitrate to climb.

Note, all of this is without coreavc.  Others have had success with a
2.4Ghz Core2, but I don't know what bitrate they were using -- The
default is 6mbit.

John
-- 
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?


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