From section 6.8.2 in the AV1 spec:

"It is a requirement of bitstream conformance that when show_existing_frame is
used to show a previous frame with RefFrameType[ frame_to_show_map_idx ] equal
to KEY_FRAME, that the frame is output via the show_existing_frame mechanism at
most once."

From section 6.8.2 in the AV1 spec:

"It is a requirement of bitstream conformance that when show_existing_frame
is used to show a previous frame, that the value of showable_frame for the
previous frame was equal to 1."

From section 6.8.2 in the AV1 spec:

"If frame_type is equal to INTRA_ONLY_FRAME, it is a requirement of bitstream
conformance that refresh_frame_flags is not equal to 0xff."

Make this a soft requirement by checking that strict standard complaince is
enabled.

Steve Lhomme authored 3 years ago and James Almer committed 3 years ago

There's an assert on n_fc == 1 at the beginning of the function. There cannot
be a second pass used here.

Signed-off-by: Steve Lhomme <robux4@videolabs.io>

picture: ensure the new seq header and op param info flags are attached to the next visible picture in display order

If the first picture in coding order after a new sequence header is parsed is
not visible, the first picture output by dav1d after the fact (which is coded
after the aforementioned invisible picture) would not trigger the new seq
header event flag as expected, despite being the first containing a reference
to a new sequence header.

Assuming the invisible picture is ever output, the result of this change will
be two pictures signaling a new sequence header was seen despite there being
only one new sequence header.

Wan-Teh Chang authored 3 years ago and James Almer committed 3 years ago

Set f->n_tile_data to 0 after the dav1d_decode_frame_exit() call in
dav1d_decode_frame(). dav1d_decode_frame_exit() unrefs every element in
use in the f->tile array, so it is good to set f->n_tile_data to 0 to
indicate that no elements are in use.

We are already doing this after all other dav1d_decode_frame_exit()
calls.

NOTE: It is tempting to have dav1d_decode_frame_exit() itself set
f->n_tile_data to 0. I did not do that in this merge request, because
the following is a common pattern:

    dav1d_decode_frame_exit(f, error);
    f->n_tile_data = 0;
    pthread_cond_signal(&f->task_thread.cond);

corresponding to the waiting code:

    while (f->n_tile_data > 0)
        pthread_cond_wait(&f->task_thread.cond,
                          &c->task_thread.lock);

I wonder if f->n_tile_data is set to 0 outside dav1d_decode_frame_exit()
to make clear the association of f->n_tile_data with the condition
variable f->task_thread.cond.

Henrik Gramner authored 3 years ago and Henrik Gramner committed 3 years ago

Split out common parts into separate functions. This reduces the
overall binary size by more than 5 KiB.

Martin Storsjö authored 3 years ago and Jean-Baptiste Kempf committed 3 years ago

This avoids build errors if such features are enabled while targeting
another binary format. (Using such features on other platforms
might require some other form of signaling/setup though, but
the ELF specific .note section isn't applicable at least.)

Fixes #277.

This clears stale values from the context in the scenario where you first parse
a svc sequence, and then a sequence header with the reduced still picture
header flag being true immediately after it.

Fixes #390.

This should avoid the risk of unexpected wraparound. This shouldn't
technically be needed for spec compliant bitstreams. In practice,
this fixes the mismatch observed in issue !388 (in checkasm generated
input data).

Cosmetic change

Wan-Teh Chang authored 3 years ago and James Almer committed 3 years ago

The dav1d_data_unref_internal(&c->in) call in close_internal() is
redundant because dav1d_flush() already calls
dav1d_data_unref_internal(&c->in).

Note that when dav1d_open() calls close_internal() with flush=0 to free
a newly constructed Dav1dContext, it is not necessary to unref c->in.

Fix memory leaks. The 'Dav1dThreadPicture cache' member was added to
struct Dav1dContext in commit f9844476.
But it is not unreferenced in dav1d_flush() or dav1d_close().

James Almer pointed out that we should unreference c->out too in
dav1d_flush().