[AG-TECH] broadcast quality video
Markus.Buchhorn at anu.edu.au
Mon Nov 4 17:08:22 CST 2002
At 09:25 AM 5/11/2002 +1100, Christoph Willing wrote:
>Just supporting Chris Osland's assertion about the H261 being more of an
>issue than the cameras themselves. We have 2 BetacamSP cameras available
>but, after passing through vic, they look no better than $200 security
since h.261 is a CIF (and QCIF) codec only, that's not surprising.
>What does work is RPTtv, described at the AG retreat earlier this year
>(http://bmrc.berkeley.edu/~delco/rtptv/). We have 2 labs (each with an
>AG node) separated by about 5km but connected with gigabit ethernet. We
>have full PAL video streaming from one AG node to the other and the
>quality is just astonishing compared with normal vic streams. Quite a
>bit more bandwidth as well of course.
For sure - we used the old Fore streamrunners with MJPEG/ATM between various sites, and it is superb, at that bandwidth. There's no inter-frame compression, hence the bigger pipe need.
The compromise between these two is h.263 (the most recent version - 2000?) which in one form or another is also used in mpeg4 and divx. It supports (almost) arbitrary frame sizes (8x8 multiple), and is very bandwidth efficient, in fact more so than h.261. I don't know if any version of vic supports it? I've used a package developed at Keio University which is mpeg4 based, and it is very very nice - at very reasonable bandwidth (less then 1Mb)
An alternate codec is mjpeg2000 - i.e. based on jpeg-2000 which is a wavelet codec, rather than the older jpeg which is DCT based. mjpg2k has similar bandwidth needs to h.263 (perhaps not quite as low), and is certainly much narrower than "normal" mjpg. It also does no inter-frame compression, which has its advantages in the face of packet loss. Morgan Multimedia has some plugins for it.
Markus Buchhorn, ANU Internet Futures Project, | Ph: +61 2 61258810
Markus.Buchhorn at anu.edu.au, mail: Bldg #108 - CS&IT |Fax: +61 2 61259805
Australian National University, Canberra 0200, Aust. |Mobile: 0417 281429
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