Reencoding video to a lower bitrate: downsample first?

[pachura]

Hi,

Let's say I need to reencode a HEVC video because my TV only supports H.264.
Or maybe it only supports bitrates up to 20 Mbit/s, while my original file is 60 Mbit/s...

Quality-wise, would it help if I slightly downsample the video just before the recompression? E.g. to 94% of the original size?

My line of thinking is that it would move a little bit boundaries between the macroblocks,
so the second compression would not amplify artifacts at these coordinates...
especially that it would use less bitrate / less effective codec.

What do you think?

[Marsia Mariner]

What do you mean by "downsample the video"?????

[pachura]

What do you mean by "downsample the video"?????

Downscale.
Specifically, 3400x1700 -> 3200x1600.

[Hoser Rob]

Downscaling is one of hte best ways to decrease bit rate while maintaing good quality. But if you're going to lower the bit rate to the point where the video file will be at most 1/3 of the original's size I don't think downscaling it to 94% is going to make a bit of difference. Downscale it a lot more, and remember ANY re encoding is going to lose some quality.