capture.lua

-- save as ~/.mpv/lua/capture.lua (new mpv versions)
-- or use as mpv --lua=/path/to/capture.lua
-- usage: press «a» at start and at end of fragment
-- will print commands for ffmpeg and mpv

capture = {}
function capture.handler()
    local gp = mp.get_property
    local gpn = mp.get_property_number
    local sp = mp.set_property
    local c = capture
    local filesize = 6144
    local maxfps = 35
    if c.start == nil then
        c.start = gp("time-pos")
    elseif c.finish == nil then
        c.finish = gp("time-pos")
        local ffopts = ""
        local length = c.finish - c.start
        local br = filesize * 8 / length - 128
        if gpn("fps") > maxfps then
            local fps = gpn("fps") / 2
        end
        local h = gp("height")
        local w = gp("width")
        if w * h / br > 1000 then
            ffopts = ffopts .. string.format("-vf scale=%d:-1 ",
                0.0017)
        end

        print(string.format("ffmpeg -ss %f -i '%s' -t %f -b:v %dk %s -pass 1",
            c.start, gp("path"), length, br,
            fps and "-r " .. fps or ""))
        print(string.format("mpv --start %f '%s' --length %f --ovcopts b=%dk",
            c.start, gp("path"), length, br))
        c.start = nil
        c.finish = nil
    end
end
mp.add_key_binding("a", "capture", capture.handler)