[mythtv-users] IVTV Bitrate & Resolution

Michael T. Dean mtdean at thirdcontact.com
Sun Mar 25 03:05:51 UTC 2007

Hello top-posters.  This is a bottom- or inline-posting list.  

I fixed your responses (so you can see what I mean).

On 03/24/2007 11:05 AM, Ma Begaj wrote:
> 2007/3/24, Matt Mossholder <matt at mossholder.com>:
>> On Sat, 2007-03-24 at 15:05 +0100, Ma Begaj wrote:
>>> 2007/3/24, Michael T. Dean <mtdean at thirdcontact.com>:
>>>> On 03/23/2007 07:23 AM, Tristan McCann wrote:
>>>>> I am using a PVR500
>>>> ...
>>>>> If I try to reduce the resolution to 640x480 or 352x480 or 480x480, it
>>>>> does more than reduce the resolution in a digital way. It actually makes
>>>>> the recording look "snowy", like there are cable reception problems.
>>>> AIUI, the PVR-150 and PVR-500 really need to record at 720x480 as most
>>>> (all?) versions of IvyTV have issues with the scaler.
>>> 720x480 ?
>>> that's not 4:3 ...   720x540 would be 4:3 ...
>>> I am using 720x540 ... should I use something else?
>> 720x480 is 4:3 for NTSC-land. 720x540 is 4:3 for PAL.
> :)) ok ... nice.
> one more question about bitrate and resolution:
> I have prv150 with geforce7600 and I am using 720x540 with 6500/9000
> bitrate for LiveTV. I watched yesterday an movie with a few fast
> scenes (running people etc). these scenes were little bit blurry.
> is this problem with too high bitrate or resolution or something else-

a) Recording resolution has nothing to do with playback aspect ratio.  
There is no requirement that video use square pixels.

b) 720x480 is the maximum DVD-compliant resolution for NTSC format.  
720x576 is the maximum DVD-compliant resolution for PAL format.  If 
you're recording NTSC, you should /not/ use >480 pixels for the "Y" 

c) Blurry scenes while recording may be due to using too little bitrate 
for the selected resolution.  If recording NTSC at > 720x480, you'll need

d) Due to the electronics in use on the PVR-x50's, you will be unable to 
improve quality of NTSC recordings by using any resolution > 640x480.  
You will likely be unable to improve quality of NTSC recordings by using 
any resolution > 480x480.  However, due to the scaling issues with the 
PVR-150 and PVR-500 and due to the fact that neither 640x480 nor 480x480 
is DVD-compliant resolution, many people record at the (too-high for the 
electronics) resolution of 720x480.

e) Regardless of the resolution you finally choose, you /must/ choose an 
appropriate bitrate or you will have poor quality recordings.  a 320x240 
recording with sufficient bitrate will /always/ be better than a 720x480 
recording with too-low a bitrate.

/me wonders if you'll actually scroll down to get to the real reason for 
my post.  If not, those who actually paid attention to the mailing list 
etiquette may find the information beneficial.


More information about the mythtv-users mailing list