[mythtv-users] HD-PVR horizontal bands

[Christopher Meredith]

On Tue, May 3, 2011 at 7:11 AM, Brian Long <briandlong at gmail.com> wrote:
> On Mon, May 2, 2011 at 4:53 PM, Christopher Meredith <chmeredith at gmail.com>
> wrote:
>>
>> I'd like to resurrect this discussion (history here:
>> http://bit.ly/k9brVY ) because I have a little more info. To recap,
>> anything recorded with my HD-PVR has thick, horizontal bars of
>> discoloration running up the screen. I have tried different cables to
>> no avail. This is the new information:
>>
>> 1. I have a video clip showing the behavior here:
>> http://www.youtube.com/watch?v=1oiNXsJVd_0 . It's most easily seen in
>> the first scene on the wall behind the characters.
>>
>> 2. Most of the previous replies had to do with group loops and AC hum,
>> but I have noticed that when watching on the TV through the HD-PVR
>> passthrough (i.e. NOT recorded content) I do not see the lines. This,
>> even though there is a second cable through which the signal must go
>> when watching this way. That suggests to me that the artifacts are not
>> in the signal when it gets to the HD-PVR.
>>
>> 3. I recently had my HD-PVR RMA replaced. The old one was a C2
>> revision, the new one is an F2. I am still noticing the behavior on
>> the new box.
>>
>> Does this information help any? Could it still be AC hum even though
>> it does not show up on the TV, despite the signal being routed through
>> the HD-PVR? Thanks!
>> http://www.youtube.com/watch?v=1oiNXsJVd_0
>
> I don't know if this could help, but have you considered altering your
> capture bitrate from CBR to VBR (or vice-versa) to see if it makes any
> difference?  What is your current profile settings as far as max bit rate
> and avg bit rate?
>
> Just an idea.

When I started this thread, I had my high quality profile set to CBR
at about 13.1 Mbps, because I wanted to get the highest possible
quality. The recording I made for the sample video was recorded at VBR
with a nominal bitrate of 3300 kbps (in fact, if you watch the second
scene in the clip, as the camera pans to the horse riders, you can see
some ugly blocking artifacts on the path around the horses' feet. I
was also going to post about that, but haven't yet).

Anyway, the point is I've seen these bands with the unit set to
highest quality setting at CBR, and at a much lower quality setting at
VBR.