[Live-devel] ONVIF support in Live555

[Cristiano Belloni]

Cristiano Belloni wrote:
> 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.
>

I forgot: if you manage to support the extensions, please let me know!

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>