How to extend the jmf by a codec, with streaming ability

Question

hi people, im sitting on a (in my eyes) realy hard challenge..
i have to build in a additional codec into the jmf and stream a file with this new built in codec ..
tryed to combine jmf with gsteamer fmj and many more but most of the time it simply dont work at all or if it works the solution lost its streaming ability.. so playing only..
any one around who could help me with this problem?
thanks in advance
sven
Edited by: InNeedOfHelp on Mar 4, 2009 5:49 AM

Answer 1

T.B.M wrote:
Sorry, I am just a 3rd year engg. student, not much experience ;-) ... you can get much more help in this regard from another experienced and knowledgeable poster *'captfoss'*, wait for him to reply. I'm glad you think of me as being experienced and knowledgeable, but I'm academiclly only about 2 years older than you ;-)
As for the codec...here's the 411 on all of that crap.
To develope a codec, you'll need to look at the following example:
[http://java.sun.com/javase/technologies/desktop/media/jmf/2.1.1/solutions/FrameAccess.html]
That example is what's known as a "pass-through" codec...it doesn't modify the data, it just passes the input into the output without modification.
A normal codec would take data of a specific format and convert it into a new format (obviously). All of the work to do that should occur in the process function.
You can specify what input formats your codec is able to handle by modifying the "getSupportedInputFormats" function. You can specify what output formats your codec is able to handle by modifying the "getSupportedOutputFormats" function. I'd recommend that you set the input formats to just take in RGB, and the output formats to just be whatever your format is.
Once you have all of the code written to process from RGB to your new format, you can officially use your codec to transcode from RGB to YNF (your new format). You'll actually need to write 3 more codecs at this point...
(1) You need to write one to take YNF and return RGB. (decode it)
(2) You need to write one to take YNF and return YNF_RTP. This could probably just be a pass-through codec, but, I'm not 100% sure as I've never written an RTP codec personally...but it'll need to be something that a Processor would see as a content type of RAW_RTP...
(3) You need to write one to take YNG_RTP and return YNF.
Once you have all of those working, you'll then need to define a custom packetizer/depacketizer for your new RTP format.
[http://java.sun.com/javase/technologies/desktop/media/jmf/2.1.1/solutions/CustomPayload.html]
This doesn't have to do anything more advanced than break the stream into chunks. The example code will probably work fine, with just the modifications necessary to make it work with your RTP format rather than the one the example uses (linear PCM wav files, as I recall)...
To summarize, you need to write the following peices of code to completely add a new format.
Encoding Codec, RTP-Encoding Codec, RTP-Decoding Codec, Decoding Codec, Packetizer, Depacketizer...
Edited by: captfoss on Mar 4, 2009 10:38 AM
Also, as a sidenote, the RTP Encoding and Decoding Codecs might not be necessary. I've never done this, I don't know anyone who has, so this is mostly educated guesswork...
Actually, if your packetizer says it'll take in the non-RTP version and packetize it, then you shouldn't actually
need the RTP codecs ;-)