AV1 decoder gets "Static surface pool size exceeded" issue with "-hwaccel d3d11va"

[Evgeny]

Summary of the bug:
When we use d3d11 hardware decoder with av1_amf encoder, the input stream is av1 format, and specify parameter hwaccel_output_format parameter, there are errors “"Static surface pool size exceeded.”

[AVHWFramesContext @ 00000166637640c0] Static surface pool size exceeded.
[av1 @ 0000016663763a00] get_buffer() failed
[av1 @ 0000016663763a00] thread_get_buffer() failed
[av1 @ 0000016663763a00] Failed to allocate space for current frame.
[av1 @ 0000016663763a00] Get current frame error
[vist#0:0/av1 @ 0000016663328740] Error submitting packet to decoder: Cannot allocate memory

This error happens only when the source is av1 format and specify -hwaccel_output_format d3d11. I tested it on nvidia machine, there are similar errors.

How to reproduce:

ffmpeg -hwaccel d3d11va -hwaccel_output_format d3d11 -i av1.mp4 -c:v av1_amf out.mp4
ffmpeg master
built on Windows with msys2