vd_lavc: let hardware decoder request delaying frames explicitly

Until now, the presence of the process_image() callback was used to set
a delay queue with a hardcoded size. Change this to a vd_lavc_hwdec
field instead, so the decoder can explicitly set this if it's really
needed.

Do this so process_image() can be used in the VideoToolbox glue code for
something entirely unrelated.

1 files changed, 5 insertions, 0 deletions

diff --git a/video/decode/lavc.h b/video/decode/lavc.h
index 44c5c27a0f..826edbff83 100644
--- a/video/decode/lavc.h
+++ b/video/decode/lavc.h
@@ -49,6 +49,11 @@ struct vd_lavc_hwdec {
     // If not-0: the IMGFMT_ format that should be accepted in the libavcodec
     // get_format callback.
     int image_format;
+    // Setting this will queue the given number of frames before calling
+    // process_image() or returning them to the renderer. This can increase
+    // efficiency by not blocking on the hardware pipeline by reading back
+    // immediately after decoding.
+    int delay_queue;
     int (*probe)(struct vd_lavc_hwdec *hwdec, struct mp_hwdec_info *info,
                  const char *codec);
     int (*init)(struct lavc_ctx *ctx);