[vlc-devel] [RFC PATCH 01/13] clock: add vlc_clock

[Thomas Guillem]

On Thu, Oct 25, 2018, at 15:54, Thomas Guillem wrote:
> 
> 
> On Fri, Aug 31, 2018, at 14:36, Zhao Zhili wrote:
> > On 8/31/18 5:59 PM, Denis Charmet wrote:
> > > Hi,
> > > 
> > > On 2018-08-29 11:10, Zhao Zhili wrote:
> > >> On 2018年06月27日 20:41, Thomas Guillem wrote:
> > >>> +static vlc_tick_t main_stream_to_system(vlc_clock_main_t * main_clock,
> > >>> +                                       vlc_tick_t pts)
> > >>> +{
> > >>> +    if (unlikely(main_clock->offset == VLC_TS_INVALID))
> > >>> +        return VLC_TS_INVALID;
> > >>> +    return (vlc_tick_t) (pts * main_clock->coeff / main_clock->rate 
> > >>> + main_clock->offset);
> > >>> +}
> > >>
> > >> I'm afraid int64_t to float to int64_t won't work well as float can
> > >> only represent a small integer precisely.
> > >> main_clock->offset makes it worse since it isn't uncommon to be a 
> > >> large value.
> > >>
> > >> (vlc_tick_t)(pts * main_clock->coeff / main_clock->rate) + 
> > >> main_clock->offset
> > >>
> > >> may be a little better, but the problem is still there.
> > >>
> > > 
> > > Thanks for the review, it's indeed a very interesting point. It seems 
> > > that switching to double might help a lot with that. Any other suggestions?
> > > 
> > > Regards,
> > 
> > double should give milliseconds precision at the worst case, but I'm not 
> > sure.
> 
> Your test confirms that a double will be OK.
> 
> > 
> > I think the math in AvgRescale is incorrect, in both the master branch 
> > and the clock-core branch. I have a patch for it
> > 
> > clock: fix AvgRescale
> > 
> > It doesn't make sense in mathematics, but it may have a special meaning 
> > I missed. And the function is not used in the clock-core branch, so it 
> > doesn't matter anymore if it's finally being removed.
> 
> It will and still be used by the input clock, even in the clock-core 
> branch.
> We'll rework and probably the input clock for VLC 5.0 when we rework the 
> buffering.
> 
> So, I'll probably merge your AvgRescale fix in our clock branch.
Ah no, this patch is not relevant on the clock-branch.

One question, I must use double in clock internal calculs, OK. But should we use double in clock external API too ? That will mean that vout/aout/input/player rate will be a double too.

> 
> > 
> > 
> > _______________________________________________
> > vlc-devel mailing list
> > To unsubscribe or modify your subscription options:
> > https://mailman.videolan.org/listinfo/vlc-devel
> _______________________________________________
> vlc-devel mailing list
> To unsubscribe or modify your subscription options:
> https://mailman.videolan.org/listinfo/vlc-devel