Using ffmpeg to halve frame rate

Steve Dodd steved424 at
Mon Apr 16 00:21:08 PDT 2018

On Sun, Apr 15, 2018 at 9:59 PM, Nick Payne <njhp94 at> wrote:

> I experimented a while ago with running some GiP downloads through
> Handbrake to convert the video to the x265 codec. That reduced the file
> size to about 1/3 of the original download, with no subjective
> difference in video quality that I could see when viewing on our TV.

Figures - most of the comparison work done on H.265 v. H.264 says you
should get same subjective quality for half the bitrate.

> A one hour 1280x720 25fps program that downloads as a 1Gb file was reduced
> in size to ~350Mb. On my PC, the re-encode runs at about 50fps for
> 1280x720, so ~2x real time for 25fps and ~real time for 50fps. For
> smaller video dimension such as 960x540, the re-encode speed was around
> 85-90FPS.

Do you know what x265 quality setting you used? I'm also experimenting
now it seems HLSHD is being turned off (series 2 of Salamander has HVF
only so far).. RF17 seems to be spitting about half the bitrate of the
BBC h.264 output, and running at ~40fps which I can live with (Core
i5-6500). Noticeable quality difference still when looking at stills,
but have tried watching it moving yet..

Incidentally, has anyone else noticed HE-AAC coming through in the
downloads recently?


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