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avfilter/internal: Improve docs about ff_request_frame()

Reviewed-by: James Darnley <james.darnley@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2015-07-14 19:44:59 +02:00
parent 550e872bcd
commit 522256b374

View File

@ -305,8 +305,27 @@ int ff_poll_frame(AVFilterLink *link);
/**
* Request an input frame from the filter at the other end of the link.
*
* The input filter may pass the request on to its inputs, fulfill the
* request from an internal buffer or any other means specific to its function.
*
* When the end of a stream is reached AVERROR_EOF is returned and no further
* frames.
*
* When a filter is unable to output a frame for example due to its sources
* being unable to do so or because it depends on external means pushing data
* into it then AVERROR(EAGAIN) is returned.
* It is important that a AVERROR(EAGAIN) return is returned all the way to the
* caller (generally eventually a user application) as this step may (but does
* not have to be) necessary to provide the input with the next frame.
*
* If a request is successful then the filter_frame() function will be called
* at least once before ff_request_frame() returns
*
* @param link the input link
* @return zero on success
* AVERROR_EOF on end of file
* AVERROR(EAGAIN) if the previous filter cannot output a frame
* currently and can neither guarantee that EOF has been reached.
*/
int ff_request_frame(AVFilterLink *link);