videoparsers: Send codec specific headers as bus messages for stream analyzer
Submitted by Sreerenj Balachandran @sree
Link to original bug (#733056)
Description
This is the placeholder for discussing the implementation of bus messages for every codec specific headers parsed by the parser plugins in gst-plugins-bad.
Codecanalzyer in gst-devtools will be one of the main user of this feature.
Method1: We already have codec specific meta for mpeg2. Downstream element can use the allocation query for informing the upstream element whether it need(it can handle) codec metas. But there should be an allocation query from upstream.
So implement something similar for every parser. That is enough from codecanalzyer's perspective. Do we really need bus messages?
Method2. Send all parsed headers to the bus as messages. This is the idea proposed by Edward and Stefan.
-- a new message for each header or a new message for each frame with all parsed headers of the corresponding frame ?
-- a new field in message to indicate the frame number should be useful.
-- the frame order from parser_plugin's source pad is different from frame order output from the decoder's src pad. how to communicate the video frames original order number (the order in which they are encoded)
and the output order number (order in which frames should be displayed) to the application?