[FFmpeg-devel] [PATCH 1/5] avfilter/af_afade: fix crossfade duration maximum value

[Paul B Mahol]

On 10/1/18, Marton Balint <cus at passwd.hu> wrote:
>
>
> On Mon, 1 Oct 2018, Paul B Mahol wrote:
>
>> On 10/1/18, Marton Balint <cus at passwd.hu> wrote:
>>>
>>>
>>> On Mon, 1 Oct 2018, Paul B Mahol wrote:
>>>
>>>> On 9/30/18, Marton Balint <cus at passwd.hu> wrote:
>>>>> Signed-off-by: Marton Balint <cus at passwd.hu>
>>>>> ---
>>>>>  libavfilter/af_afade.c | 4 ++--
>>>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>
>>>>
>>>> Why?
>>>>
>>>> Value is too big.
>>>
>>> AV_OPT_TYPE_DURATION is microsecond precision, therefore 60 is 60 usecs.
>>> Probably you meant 60 seconds as limit. That is what the patch fixes.
>>
>> I do not think so. Duration is interpreted as seconds, look how
>> variable is used in code.
>
> As far as I see duration is rescaled from AV_TIME_BASE (microseconds) to
> sample_rate time base:
>
> if (s->duration)
>       s->nb_samples = av_rescale(s->duration, outlink->sample_rate,
> AV_TIME_BASE);
>
> Duration is parsed as seconds (can be fractional as well), but internally
> it is stored as microseconds (int64). Another example is the f_realtime
> filter where the sleep time limit default according to the documentation
> is 2 seconds and it is expressed as 2000000 in the code.

Yes, and current patch is wrong. Simply exceding max value is not proper fix.