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. > > >> + usec = ntp_time % 1000000; >> + >> + //encoding in ntp timestamp format >> + frac_part = usec * 0xFFFFFFFFULL; >> + frac_part /= 1000000; >> + >> + ntp_ts = (uint64_t) sec; >> + ntp_ts <<= 32; >> + ntp_ts |= frac_part; >> + >> + return ntp_ts; > > this looks similar to what av_rescale does. Not really. This is a unique format as defined in RFC 5905. (please see this page for high level understanding of this format http://www.beaglesoft.com/Manual/page53.htm ) > > > also ff_time_ntp_format() is a bad name. It does not give any hint > on if ntp time is the input or output of the call Okay. I will submit a revised patch with a more meaningful function name. How does 'ff_get_formatted_ntp_time' sound like? > > [...] > > > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
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