Called when appsrc has enough data. It is recommended that the application stops calling push-buffer until the need_data callback is emitted again to avoid excessive buffer queueing.
Called when the appsrc needs more data. A buffer or EOS should be pushed to appsrc from this thread or another thread. @length is just a hint and when it is set to -1, any number of bytes can be pushed into @appsrc.
Called when a seek should be performed to the offset. The next push-buffer should produce buffers from the new @offset. This callback is only called for seekable stream types.
A set of callbacks that can be installed on the appsrc with gstapp.app_src.AppSrc.setCallbacks.