some problem with the buffer and work mechanism of mfc_decoder

[Sebastian Dröge]

On Fr, 2014-01-03 at 14:20 +0800, randy wrote:
> Hello
>   I am doing a encoder of using exnoys 4412 mfc encoder, but the
> example from samsung is some dfficult to understand, so I begin with
> gstreamer. I know few about gstreamer and glib(only some developed
> before). And I don't know memory to memory driver well.
> After using request_input_buffers in mfc_decoder/mfc_decoder.c, the
> mfc_dec_context's input_buffer has been mapped with device, I think I
> shall fill all the encoded_data into it, but I don't see it is used in
> gstmfcdec.c, it is also same for mfc_dec_context's output_buffer.
> And about gst_mfc_dec_queue_input, it dequeue first, I think it shall
> enqueue with the first frame first.
> It is same with gst_mfc_dec_queue_output.

See the memcpy() calls in gstmfcdec.c, there the data is copied from/to
the device's buffers.

Note however that mfcdec was just a proof of concept and there's work
happening right now to write a proper v4l2 based video decoder element
that is using the v4l2 infrastructure from gst-plugins-good.

Current work in progress is here:
http://cgit.collabora.com/git/user/nicolas/gst-plugins-good.git/log/?h=v4l2videodec

I'm sure Nicolas or Benjamin can tell a bit more about the current
status.

-- 
Sebastian Dröge, Centricular Ltd - http://www.centricular.com
Expertise, Straight from the Source
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