[FFmpeg-devel] [PATCH] parseutils: add support for ms and us suffix for AV_OPT_TYPE_DURATION

[Hendrik Leppkes]

On Fri, Mar 2, 2018 at 11:19 PM, Aurelien Jacobs <aurel at gnuage.org> wrote:
> On Fri, Mar 02, 2018 at 10:02:58PM +0000, Rostislav Pehlivanov wrote:
>> On 2 March 2018 at 21:57, Aurelien Jacobs <aurel at gnuage.org> wrote:
>>
>> > On Fri, Mar 02, 2018 at 09:39:48PM +0100, Michael Niedermayer wrote:
>> > > On Thu, Mar 01, 2018 at 09:41:20PM +0100, Aurelien Jacobs wrote:
>> > > > supported suffixes are:
>> > > > - s: seconds (default when no suffix specified)
>> > > > - m or ms: milliseconds
>> > > > - u or us: microseconds
>> > > > ---
>> > > >  libavutil/parseutils.c | 15 +++++++++++++--
>> > > >  1 file changed, 13 insertions(+), 2 deletions(-)
>> > >
>> > > can some of this and the si_prefixes related code in eval.c be
>> > > factored ?
>> >
>> > I've had a look at this, but this would increase code complexity
>> > in both eval.c and parseutils.c with no advantage, so I deceided not to.
>> > Anyway, 'u' and 'm' SI prefix are the only ones that make any sense for
>> > AV_OPT_TYPE_DURATION and supporting more prefix than those "thanks" to
>> > common code, might add confusion for end user.
>> >
>> > BTW, while looking at si_prefixes, I noticed that both 'k' and 'K' are
>> > supported for meaning "kilo", which is wrong in the SI. Only 'k' is
>> > a prefix for "kilo", 'K' is a unit for "Kelvin".
>> > Not sure if there is actually a good reason for having 'K', if it is
>> > needed for backward compatibility, or if it should be removed...
>> >
>> > > either way this LGTM
>> >
>> > Great. Applied.
>> > _______________________________________________
>> > ffmpeg-devel mailing list
>> > ffmpeg-devel at ffmpeg.org
>> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >
>>
>> I think that was a bit premature, I really think "m" should be for minutes
>> while "ms" should be for milliseconds.
>
> What you (or I) think is not relevant here. We are simply implementing
> an internationnal standard that define precisely what those letters mean
> so that people all around the world can communicate without ambiguity.
>

Why is it not relevant what we think? Who said this has to follow
strict SI rules?

It should use postfixes which are the most logical and intuitive, and
when someone reads "5m" he is the most likely to assume minutes, not
milliseconds.

- Hendrik