[gst-devel] addition of a buffer flag

[Ronald Bultje]

Hi,

can't the mux rsimply extract this data from the packets directly? Note
that other codecs use the GstCaps property 'codec_data' for this. Matroska
treats Vorbis headers that way, too. The only notable exception to this
rule is really Ogg itself...

I'd say that a caps-property is cleaner.

Ronald

On Wed, 12 May 2004, Thomas Vander Stichele wrote:

> Hi,
>
> for streaming purposes, we need a way for the network elements to know
> what part of the beginning of a data stream are to be considered
> "headers" and what is the raw data.  This isn't necessary for every
> format, but it is a requirement for Ogg.
>
> As an example, here's what needs to be done to stream Ogg/Theora+Vorbis.
>
> a) ogg page 1 contains a header for the vorbis stream
> b) ogg page 2 contains a header for the theora stream
> c) ogg page 3 contains two extra headers for the vorbis stream
> d) ogg page 4 contains two extra headers for the theora stream
> e) ogg page 5 is the first page containing data packets
>
> Every new client that picks up in the middle of the stream needs to
> first receive the first four ogg pages.  (Contrast with an mp3 stream,
> where you can pick in any time since each mp3 frame is preceded by a
> header, or with mpeg-video where the codec can choose to repeatedly send
> header info every few seconds).
>
> We discussed the various options.  We wanted to attach the information
> that some buffers represent a reusable header to the stream, instead of
> signalling it out-of-band through signals/deep_notify and property
> setting.
>
> So the choice is between events or buffer flags.  I prefer a buffer flag
> because it's the cleanest implementation:
> - the vorbis codec would generate the three packets of header info
> marked with this flag
> - same for theora
> - ogg muxer assembles pages with this flag
> - network streaming element looks at incoming flags, and puts all
> incoming buffers with this flag on an internal queue
> - every new connection to this element first receives the stored headers
> before picking in anywhere in the data stream.
>
> So, can I go ahead and add a _HEADER buffer flag for this ?
>
> Thomas
>
> Dave/Dina : future TV today ! - http://www.davedina.org/
> <-*- thomas (dot) apestaart (dot) org -*->
> Won't you come a
> little closer
> close enough so
> I can smell you
> <-*- thomas (at) apestaart (dot) org -*->
> URGent, best radio on the net - 24/7 ! - http://urgent.fm/
>
>
>
>
> -------------------------------------------------------
> This SF.Net email is sponsored by Sleepycat Software
> Learn developer strategies Cisco, Motorola, Ericsson & Lucent use to deliver
> higher performing products faster, at low TCO.
> http://www.sleepycat.com/telcomwpreg.php?From=osdnemail3
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>