[mythtv-users] IVTV Bitrate & Resolution

Michael T. Dean mtdean at thirdcontact.com
Sun Mar 25 17:10:00 UTC 2007

On 03/25/2007 09:50 AM, Cory Papenfuss wrote:
>> 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"
>> resolution.
>  	... or <480 for that matter.  NTSC has 480 visible lines with 
> interlacing.  Using anything other than ___x480 is generally a bad idea. 
> Even 352x480 produces pretty good (VHS-quality) recordings.  352x240 looks 
> like crap.  In fact, I recall playing around with that at one point. 
> IIRC, recording at 176x480 looked better than 352x240 (same number of 
> pixels).

Agreed, but was trying to emphasize the >480 doesn't help since the OP 
is using an unusual >NTSC, but <PAL resolutino.  (However, since the OP 
is using PAL, he should use 576.)

>> 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.
>  	704x480 is also a DVD-friendly resolution.  Not much difference, 
> but no point in doing 720x480 either.... it's not "more standard"

However, AIUI, 704x(480|576) is a "cut" resolution--which is supposed to 
have clean edges.  DVD's with video at 704x(480|576) are supposed to be 
played back with less overscan (though I don't know of any specific 
players that actually do so).

Since the PVR-x50's do /not/ have clean edges on their recordings, my 
recommendation is to stay away from 704x(480|576) unless transcoding 
/and/ cropping.  Otherwise, you may stumble across some player that does 
overscan less and you'll see black frame and/or jaggies and/or rainbow 
edges on the TV.


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