diff options
Diffstat (limited to 'libavfilter')
| -rw-r--r-- | libavfilter/internal.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/libavfilter/internal.h b/libavfilter/internal.h index a7ec751a0f..9dded84a38 100644 --- a/libavfilter/internal.h +++ b/libavfilter/internal.h @@ -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); |