Allow negative values for the speed option to reverse playback

[saagarjha]

mpv version and platform

mpv 0.23.0, macOS 10.12.3 (16D17a)

Reproduction steps

mpv foo.mp4 --start=50% --speed=-2

Expected behavior

mpv launches, starts the video and 50%, and plays the video in reverse at 2x speed.

Actual behavior

mpv fails to launch with the following error:

The speed option is out of range: -2
Error parsing option speed (parameter is outside values allowed for option)
Setting command line option '--speed=-2' failed.

Log file

N/A

Sample files

N/A

[wiiaboo]

Inter-frame codecs (most in use today) don't work well with reverse playback.

This is probably a wontfix, c.f. #3805

[saagarjha]

Is there no way to provide rudimentary support for this by skipping to individual frames (in reverse order)? It's fine if it doesn't run at 60 FPS.

[ghost]

You can get a similar effect by keeping the , key (for frame backstep) pressed. Of course it's very slow.

Real backwards playback would be a nice thing, but definitely not easy to add. You could try a gstreamer player, since gstreamer has support for true backwards playback - I've never seen it in action anywhere, though.

[TeoColuccio]

Has there been any significant update? I also experienced the experience of the creator of the post

[CounterPillow]

@TeoColuccio you can use --play-dir=- now.

[TeoColuccio]

@TeoColuccio you can use --play-dir=- now.

This option is already very useful to me, but is there any way to do this while I'm playing in normal mode?

[CounterPillow]

I'm not sure what you mean by "normal mode"

[TeoColuccio]

I'm not sure what you mean by "normal mode"

I mean a normal playback of a video. While I play frame-by-frame forwards, I would also like to be able to play frame-by-frame in reverse.

[CounterPillow]

That's what setting the play-dir to - does. The forward (.) keybind then goes backwards. You can bind any key you want with
KEY cycle-values play-dir - + in your input.conf

Please no longer pollute this old issue with questions, the original reporter does not need notifications about this. If you still have questions, open a new issue, and properly explain what you want to do, what you expect it to do, and how it currently behaves.

[varenc]

Could play-dir get a keybinding in the default input.conf? I've seen several long time mpv users suddenly just discover this amazing functionality. (though I do wish its interface was a negative speed, but I digress)