[MEncoder-users] Low res video playback in high res

[Bill Crockett]

> On Sun, Apr 03, 2016 at 09:04:58PM +1000, Bill Crockett wrote:
>> >>> Just wondering if it is possible to either re-encode or play back
>> >>> a 1280x720 video in 1920x1080 resolution without losing sharpness,
>> >>> detail
>> >>> ...etc?
>> >>
>> >> Sorry to have to say this, but it is impossible.  See for yourself:
>> >>
>> >> mplayer -vf scale=1920:1080 your_video
>> >>
>> >> It is like zooming in.  Quality goes out the window.
>> >
>> > There are better scaling windows (-sws) but if you consider that as
>> > quality
>> > going out the window probably nothing will make you happy...
>> > Though if sharpness, detail, .. is the only concern you can use
>> > nearest-neighbour scaling.  It will not lose any, but it will likely 
>> > look
>> > a bit
>> > strange and bad since every other line/column becomes twice as
>> > high/wide. Definitely no loss of sharpness or anything though.  As the
>> > scale
>> > factor is 1.5 it should be possible to do better by not just 
>> > duplicating
>> > every
>> > other row/column but instead inserting the average.  But it will likely
>> > look
>> > more blurry even though it is not.
>>
>> I thought the -sws 9 (lanczos) was the best choice.   -sws 4 nearest
>> neighbour (bad quality)
>
> There is no "best" without specifying the criteria.
> Lanczos is considered on of the best looking by most people
> in most cases. That doesn't change that e.g. I don't like
> it compared to a smooth bicubic and that it e.g. fails
> very badly at scaling content that was scaled before.
> Also you specifically asked about preserving content.
> For upscaling -sws 4 will 100% preserve the data, which
> Lanczos cannot guarantee. To most people it will look
> like crap if you upscale by around 2x or more though.
>
>> Are you referring to -vf  ilpack=0
>> nearest-neighbour sampling?  Are these option the best?
>
> No, I don't see what ilpack has to do with it.
>
>> mencoder -sws 9 -vf scale=1920:1080 (encoding options) -o
>> 1920_1080_video.mpg 1280_720_video.mpg
>
> Also, what I said so far applied to viewing.
> Presuming you are not using an extremely high, near-lossless
> bitrate, Lanczos due to creating sharpening and ringing is
> likely to vastly increase bitrate/decrease quality.
> Upscaling, especially at a factor 1.5, before encoding will
> cost you a lot and if in any way possible you should of
> course avoid it, so under that aspect these clearly aren't
> good options. But I assume you have a reason.
> Also why 1800? Just typo I guess?

Sorry about that. Yes, it should be 1080.  I've corrected it above.

Actually, I am using a very high bitrate in the encoding options.  I will 
experiment with the -sws 4 and compare.  I guess my eyes have to decide 
which look better.  Thanks for your knowledge and info on this.