v4l2videodec: support orphaning

Recent kernels allow REQBUFS(0) on a queue that still has buffers in
use (mmapped or exported via dmabuf), orphaning all buffers on the queue.
If this is supported, the v4l2videodec element does not have to send a
drain request downstream.
This commit is contained in:
Philipp Zabel 2019-01-24 16:12:13 +01:00 committed by Nicolas Dufresne
parent dfc20013cc
commit e2ff87732d

View file

@ -233,19 +233,20 @@ gst_v4l2_video_dec_set_format (GstVideoDecoder * decoder,
gst_v4l2_video_dec_finish (decoder);
gst_v4l2_object_stop (self->v4l2output);
/* The renegotiation flow don't blend with the base class flow. To
* properly stop the capture pool we need to reclaim our buffers, which
* will happend through the allocation query. The allocation query is
* triggered by gst_video_decoder_negotiate() which requires the output
* caps to be set, but we can't know this information as we rely on the
* decoder, which requires the capture queue to be stopped.
/* The renegotiation flow don't blend with the base class flow. To properly
* stop the capture pool, if the buffers can't be orphaned, we need to
* reclaim our buffers, which will happend through the allocation query.
* The allocation query is triggered by gst_video_decoder_negotiate() which
* requires the output caps to be set, but we can't know this information
* as we rely on the decoder, which requires the capture queue to be
* stopped.
*
* To workaround this issue, we simply run an allocation query with the
* old negotiated caps in order to drain/reclaim our buffers. That breaks
* the complexity and should not have much impact in performance since the
* following allocation query will happen on a drained pipeline and won't
* block. */
{
if (!gst_v4l2_buffer_pool_orphan (&self->v4l2capture->pool)) {
GstCaps *caps = gst_pad_get_current_caps (decoder->srcpad);
if (caps) {
GstQuery *query = gst_query_new_allocation (caps, FALSE);