poor attempt to add s436m codec

[dericed]

Hey Tjoppen, I've been trying to fight an FFmpeg learning curve in order to start writing some s436m support (in the hope of allowing mxf-to-mxf copying to s436m vbi tracks). I started writing a libavcodec/s436m.c although I'm not sure if this needs to be done for enabling copying. Right now I can an error on make:

libavcodec/s436m.c:27: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘attribute’ before ‘ff_s436m_decoder’
make: *** [libavcodec/s436m.o] Error 1

Could you skim what I've done so far? I'd be very grateful for any further clues.
dave

[Tjoppen]

I'd consider this a data codec, not a subtitle codec since VBI data can be anything. Notably teletext, which I wouldn't consider subtitles.
You shouldn't need to add a decoder - just add a CodecID and the corresponding ULs to mxf.c, mxfdec.c and mxfenc.c. I forget how exactly, but look how AVMEDIA_TYPE_AUDIO is handle for instance.

[dericed]

See Carl's advice here: http://ffmpeg-users.933282.n4.nabble.com/data-codecs-td4331988.html
Thanks for the help, I'll try that.

[Tjoppen]

I have S436m, and it does indeed seem to only concern generic VBI data. Searching for "subtitle" in the document gives no hits. Hence AVMEDIA_TYPE_DATA seems appropriate, unless VBI should have its own media type..

[dericed]

I added the UL to mxfdec.c but obviously made an error. As my XDCam files are being listed as:
Stream #0:8: Audio: s436m, 48000 Hz, 1 channels
Stream #0:9: Data: none