[mythtv-users] Speaking of transocding: 1080i deinterlace?
brad+myth at templetons.com
Fri Feb 13 23:35:18 UTC 2009
On Fri, Feb 13, 2009 at 01:05:39PM -0800, Brad Templeton wrote:
> Speaking of transcoding HDTV, in particular 1080i recordings,
> I wonder if people might share their success stories on this.
> I have four possible goals for transcoding 1080i. (720p is pretty
> easy to figure out)
> a) Keep all 1080 lines, but save disk space
> Presumably: Turn on interlaced DCT and interlaced motion estimation
> Keep video size the same.
> Set to around 6 megabits/second (to taste)
> b) Reduce the resolution to 1280x720, deinterlace,
> Do we put a filter in custom filters like kerndeint?
> Do we leave interlaced DCT and motion estimation off, as the
> filter will come first?
> c) Reduce the resolution to 1280x540 or even 1080x540, giving
> up half the lines and of course deinterlacing.
> Do we use a different filter than above? Perhaps "onefield"
> is simpler or is it better to stick with kerndeint or
> d) Reduce SDTV video that was upconverted and letterboxed back to SDTV
> 1) Reduce to 960x540 to get a perfect deinterlace.
> What is the best filter and flag setting for that?
> 2) Reduce to 854x480 to match the true lines in recording.
> What is the best approach?
> 3) Reduce to 720x540, cropping off the letterbox bars
> Can the crop filter of mythtranscode do this? The
> docs suggest it adds bars. This is my ideal choice
> for a perfect deinterlace and quality recording
> For 720p recordings, it's all much simpler, no deinterlace issues,
> though for upconverted SDTV it would be nice to crop but since I
> presume the mp4 codec wastes little space on the letterbox bars
> that it isn't a huge issue.
> What success have people had?
Ok, looking at the source code for mythtranscode, the options
for interlaced dct and motion estimation are simply ignored as
far as I can tell, so that simplifies the answer about whether to
turn them on or off. If correct, these options should be removed
from the setup screens, or implemented.
The filters options are used, however, my attempt to use "onefield"
and "kerneldeint" did not appear to deinterlace the recording.
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