[Live-devel] Possible to join multicast and extract jpegs?

[Thomas Christensen]

Den 08/08/2006 kl. 23.13 skrev Ross Finlayson:

>> I want to extract images from a multicasted mpeg2 transport stream
>> TS. The TS is raw udp and does not use RTP. I figure the required
>> streps are the following:
>>
>> 1. Receive MPEG2-TS and keep a buffer that only keeps the latest
>> couple of screens
>> 2. Extract a key-frame from that buffer and save as jpeg
>
> Well, you've missed two *very* important steps in the middle of 2:
> - decode the MPEG-2 frame
> - reencode the decoded frame to JPEG
The two obvious MPEG decoders are VLC and MPlayer. I had hoped for  
other extensions of the Live library to perform the requested  
operation. However it turned out that MPlayer can do exactly what I  
was looking for:

./mplayer -ss 00:00:01 -frames 1 -nosound -vop scale=704:567 - 
jpeg:outdir=img udp://@239.1.1.91:5501

Drops a frame from the specified multicast as jpeg in directory img

If someone on this list knows of other and lighter decoders (open  
source), let me know.

Thanks,

Thomas