[FFmpeg-devel] [PATCH] parseutils: accept only full "ms" and "us" prefixes

[Bodecs Bela]

2018.03.03. 21:19 keltezéssel, Rostislav Pehlivanov írta:
> The commit which added those was pushed prematurely before anyone could object
> to illogical suffixes like just m for milliseconds. Without this, we'd be locked
> into never being able to implement the "m" suffix for minutes.
>
> Signed-off-by: Rostislav Pehlivanov <atomnuker at gmail.com>
> ---
>   libavutil/parseutils.c | 10 ++++------
>   1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/libavutil/parseutils.c b/libavutil/parseutils.c
> index 44c845577a..1b81757aab 100644
> --- a/libavutil/parseutils.c
> +++ b/libavutil/parseutils.c
> @@ -689,17 +689,15 @@ int av_parse_time(int64_t *timeval, const char *timestr, int duration)
>   
>       if (duration) {
>           t = dt.tm_hour * 3600 + dt.tm_min * 60 + dt.tm_sec;
> -        if (*q == 'm') {
> +        if (q[0] == 'm' && q[1] == 's') {
>               suffix = 1000;
>               microseconds /= 1000;
> -            q++;
> -        } else if (*q == 'u') {
> +            q += 2;
> +        } else if (q[0] == 'u' && q[1] == 's') {
>               suffix = 1;
>               microseconds = 0;
> -            q++;
> +            q += 2;
>           }
> -        if (*q == 's')
> -            q++;
>       } else {
>           int is_utc = *q == 'Z' || *q == 'z';
>           int tzoffset = 0;
I read the other thread about this problem.
I think the problem is that SI prefixes u (micro) m (mili) h (hecto) d 
(deci) k (kilo) M (mega) etc may overlap with time period names: s 
(second) m (minutes) h (hour) d (day) etc.
Because only second can have prefixes (mili sec, micro sec, nano sec ) 
among time period names, thus your solution is good workaround.
But it will be complete only if we use this logic for nano sec also. But 
I am not sure if ffmpeg uses nano sec anywhere.

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