[Live-devel] ONVIF support in Live555

[Cristiano Belloni]

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>
belloni at imavis.com <mailto://belloni@imavis.com>