On Fri, Apr 27, 2018 at 08:00:23AM +0000, Dixit, Vishwanath wrote: > > > On 4/27/18 5:15 AM, Michael Niedermayer wrote: > > On Thu, Apr 26, 2018 at 11:05:59AM +0000, Dixit, Vishwanath wrote: > >> > >> > >> On 4/26/18 1:04 AM, Michael Niedermayer wrote: > >>> On Tue, Apr 24, 2018 at 02:46:56PM +0530, vdi...@akamai.com wrote: > >>>> From: Vishwanath Dixit <vdi...@akamai.com> > >>>> > >>>> This utility function creates 64-bit NTP time format as per the RFC > >>>> 5905. > >>>> A simple explaination of 64-bit NTP time format is here > >>>> http://www.beaglesoft.com/Manual/page53.htm > >>>> --- > >>>> libavformat/internal.h | 8 ++++++++ > >>>> libavformat/utils.c | 20 ++++++++++++++++++++ > >>>> 2 files changed, 28 insertions(+) > >>>> > >>>> diff --git a/libavformat/internal.h b/libavformat/internal.h > >>>> index 3582682..e9f758f 100644 > >>>> --- a/libavformat/internal.h > >>>> +++ b/libavformat/internal.h > >>>> @@ -240,6 +240,14 @@ void ff_read_frame_flush(AVFormatContext *s); > >>>> uint64_t ff_ntp_time(void); > >>>> > >>>> /** > >>>> + * Get the NTP time stamp formatted as per the RFC-5905. > >>>> + * > >>>> + * @param ntp_time NTP time in micro seconds (since NTP epoch) > >>>> + * @return the formatted NTP time stamp > >>>> + */ > >>>> +uint64_t ff_time_ntp_format(uint64_t ntp_time); > >>>> + > >>>> +/** > >>>> * Append the media-specific SDP fragment for the media stream c > >>>> * to the buffer buff. > >>>> * > >>>> diff --git a/libavformat/utils.c b/libavformat/utils.c > >>>> index c25eab4..b59d426 100644 > >>>> --- a/libavformat/utils.c > >>>> +++ b/libavformat/utils.c > >>>> @@ -4637,6 +4637,26 @@ uint64_t ff_ntp_time(void) > >>>> return (av_gettime() / 1000) * 1000 + NTP_OFFSET_US; > >>>> } > >>>> > >>>> +uint64_t ff_time_ntp_format(uint64_t ntp_time) > >>>> +{ > >>>> + uint64_t ntp_ts, frac_part; > >>>> + uint32_t sec, usec; > >>>> + > >>>> + //current ntp time in seconds and micro seconds > >>> > >>>> + sec = ntp_time / 1000000; > >>> > >>> This can be truncated > >> Yes, but the truncated part is not getting discarded, as the following > >> line is taking care of that. Please correct me if I have not understood > >> what you have intended to say here. > > > > ok, correcting you then :) > > sec is 32bit > > not all values of "ntp_time / 1000000;" fit in 32bit > > there is no check for this it just produces a wrong result > Yes, you are right. But, I can use only the LS 32bits of the result in the > following code. It is a limitation of 64-bit NTP time format and the issue is > going to occur in 2036. Not sure how to handle it here. At most, I can print > a warning message when the result gets truncated. Could you please suggest > any alternative option?
i cant make it work after 2036 as that seems what the design is limited at. But the error can be detected and handled [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Observe your enemies, for they first find out your faults. -- Antisthenes
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