Re: Streaming live video.

[<br...@pr...>]

On Jun 9,  9:19, Sebastien Rougeaux wrote:
>
> Brian> It works well with their UST/MSC system, which assigns a 64-bit
> Brian> nanosecond accuracy timestamp (relative to machine reset time) and a
> Brian> 'media count' (i.e. frame count) to each incoming media unit
> Brian> (i.e. frame) around the circular buffer, so you can accurately match up
> Brian> similarly-labelled incoming audio, detect dropped frames, etc. Outgoing
> Brian> data can also be accurately synced to absolute time and/or other media
> Brian> types. In the case of 1394/DV, you would also want to associate DV
> Brian> timecode and 'time of day' timestamps to incoming frames.
> 
> I am not familiar with the DV format, but isn't there already some kind of
> timestamp encoded in the DV frame already ?

I'm not familiar either, but I understand it has an hh:mm:ss:ff timecode
or equivalent, as well as an (optional?) time-of-day timestamp so 
camcorders no longer need to burn it into the video image.

The UST/MSC stuff is especially meaningful when capturing from analog
sources which don't have their own inherent timestamp. The SGI effectively
assigns a timestamp to the video stream as soon as the signal crosses the
RCA jack, so there is an absolute time basis with which to relate
other incoming/outgoing video, audio, midi events, serial port characters,
keypresses etc. (e.g. you can specify that each serial character is to
be transmitted at a specific UST time).

I only bring it up because at some stage Linux may want a systemic view
of media timestamping, and I thought I'd throw it into the melting pot
now ...

Cheers
Brian.

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Brian Murray      Proximity Pty Ltd
http://www.proximity.com.au/~brian/
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