Matt Schuckmann wrote:
We use MJPEG over RTP to send on demand hi resolution still images
along side our video which is lower res H.264.
Is there an extension to the MJPEG standard that allows JPEG over 2k x
2k? If so we'd be interested in implementing it.
Matt S.
Matt, don't top-post please.
As far as I know, MJPEG already supports > 2048 dimensions, it's MJPEG
over RTP (aka the RTP payload for MJPEG standard) that doesn't support
them, as you can see in RFC 2435.
However, there is a MJPEG-over-RTP extension that allows that, and this
extension is proposed in the ONVIF core specification v 1.0.1. You can
find that document here, in PDF form:
http://www.onvif.org/Documents/Specifications/tabid/284/Default.aspx
More specifically, you'll find the whole technical specification of the
extension starting from paragraph 11.1.3.
The way to support the extension in liveMedia involves writing support
for RTP header extension in liveMedia lib, and writing an MJPEG source
and sink that can handle the ONVIF headers in your application code
(Ross, correct me if I'm wrong).
Regards,
Cristiano.
Cristiano Belloni wrote:
Ross Finlayson wrote:
Someday we will support RTP header extensions (though not
necessarily this particular application of them (see above)).
More generally, though, I'm curious about why people are still
interested in JPEG-over-RTP, especially with very large JPEG images.
JPEG is a *terrible* codec to use for video; it doesn't have any of
the inter-frame prediction/compression features that real video
codecs have.
I know your opinion on this topic.
The reason why people is still interested in JPEG streaming is that
hardware MPEG4 and H264 encoders often simply don't support higher
resolutions (for example, MPEG4 on TI DaVinci platforms is limited to
1280x960, and H264 has a resolution limit that's only a tad higher),
while JPEG encoder often support resolutions of up to 10K x 10K pixel.
So often, especially when you have to stream big frames, MJPEG is all
you have, and you got to live with it. That's why people still are
still interested in it (for sake of completeness there's another -
secondary - reason, i.e. retrocompatibility with older software).
Regards,
Cristiano.
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Belloni Cristiano
Imavis Srl.
www.imavis.com <http://www.imavis.com>
[email protected] <mailto://[email protected]>
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