Hi I sort of suspect that if there *was* a system “broadcasting” time over the internet (other than NTP) we all would be fooling around locking up oscillators to it …
Yes, streaming and time stamping are not the same thing. These days though, the two probably get crossed between a lot. Bob > On Dec 21, 2015, at 10:22 AM, Jim Lux <jim...@earthlink.net> wrote: > > On 12/21/15 3:19 AM, Tim Shoppa wrote: >> As an adjunct to the thread about timestamped samples of LORAN >> transmissions... >> >> Are there any standard consumer-type audio file formats, that support >> absolute time time/datestamps? Would not have to be done continuously, but >> something like a time and date stamp inserted nearest each sample on a >> second boundary. >> >> I have worked with some analog tape audio formats in the past where >> IRIG-type timestamps were written on a separate channel or on a subcarrier. >> >> I know of many proprietary digital recording applications that make WAV's >> or MP3's or proprietary codec formats, where the filename includes a >> timestamp. Much more interested in standard formats where the timestamp is >> embedded in the file itself. >> > > For RF recordings, VITA49 has a standard for timestamps in the packet headers > (4 flavors of epoch, multiple flavors of time format and precision) > > Video file formats seem to draw from older time code things like SMPTE and > are "relative" (so you're always fooling around trying to figure out the > offsets). I spent a few days earlier this year trying to put absolute time > subtitles on video files using all manner of tools, and it was frustrating > (ffmpeg, vlc, etc.. all were to no avail). Trying to put UTC time into > embedded timecode was also pretty unproductive (most tools don't like to see > the first frame occurring at a time very different from 00:00:00:00) > > > In fact, in the music file world (e.g. MIDI) you see references to absolute > and relative time, and there, they are really talking about time measured in > seconds vs time measured in beats; e.g. whether the duration of something is > 1 second, or 2 quarter notes, which might be the same if the tempo is 120bpm. > > > You might look for solutions for people trying to synchronize multiple > multimedia streams delivered over the internet (e.g. slides and accompanying > narration or music) because they actually have a need for "show this slide at > time HH:MM:SS and play this sound at HH:MM:SS" kind of synchronization. > > I suspect, though, that this kind of info gets encapsulated in the transport > layer, rather than the underlying files holding the info. > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
