That function is currently very long and entangles bitstream parsing and
decoder configuration. This makes the code much harder to read than
necessary.
Begin splitting the code that configures the decoder state based on the
slice header information from the parsing of the slice header.
In such a case, decode the MBs in parallel without the loop filter, then
execute the filter serially.
The ref2frm array was previously moved to H264SliceContext. That was
incorrect, since it applies to all the slices and should properly be in
H264Context (it did not actually break decoding, since this distinction
only becomes relevant with slice threading and deblocking_filter=1,
which was not implemented before this commit). The ref2frm array is thus
moved back to H264Context.
It is always unconditionally initialized in decode_postinit() and then
immediately used in one place further below. All the other places where
it is accessed are just useless fluff.
Make the SPS/PPS parsing independent of the H264Context, to allow
decoupling the parser from the decoder. The change is modelled after the
one done earlier for HEVC.
Move the dequant buffers to the PPS to avoid complex checks whether they
changed and an expensive copy for frame threads.
According to the spec, the reference list for a slice should be
constructed by first generating an initial (what we now call "default")
reference list and then optionally applying modifications to it.
Our code has an optimization where the initial reference list is
constructed for the first inter slice and then rebuilt for other slices
if needed. This, however, adds complexity to the code, requires an extra
2.5kB array in the codec context and there is no reason to think that it
has any positive effect on performance. Therefore, simplify the code by
generating the reference list from scratch for each slice.
The container cropping is applied only when difference is within 16
pixels, and the smallest value between the two is chosen.
Bug-Id: 383
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Also use the frame pixel format instead of the one from the codec
context, which is more robust.
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
It does not make sense to copy is_avc without copying this as well. This
patch should not change anything for now, but will have an effect in
later commits.
That function currently does two things -- reinitializing the DSP
contexts and setting low_delay based on the SPS values.
The former more appropriately belongs in h264_slice_header_init(), while
the latter only really makes sense in decode_slice_header().
The third call to ff_h264_set_parameter_from_sps(), done immediately
after parsing a new SPS, appears to serve no useful purpose, so it is
just dropped.
Also, drop now unneeded H264Context.cur_chroma_format_idc.
Currently, the DPB is initialized in alloc_tables() and uninitialized in
free_tables(), but those functions manage frame size-dependent
variables, so DPB management does not logically belong in there.
Since we want the init/uninit to happen exactly once per the context
lifetime, init_context()/free_context() are the proper place for this
code.
