Given that the AVCodec.next pointer has now been removed, most of the
AVCodecs are not modified at all any more and can therefore be made
const (as this patch does); the only exceptions are the very few codecs
for external libraries that have a init_static_data callback.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>
ff_init_vlc_from_lengths() can be used to offload the computation
of the codes; it also needn't check whether the codes are already
properly ordered (they are).
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
The SheerVideo decoder uses two VLC tables and these are in turn created
from structures (called SheerTable) that are naturally paired. This
commit unifies these pairs of SheerTables to arrays and unifies creating
the VLC tables.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
The SheerVideo decoder uses VLC tables which are currently stored in
large arrays that contain the length of each leaf of the corresponding
tree from left to right, taking 15.5KB of space. But all these arrays
follow a common pattern: First the entries are ascending and then they
are descending with lots of successive entries have the same value.
Therefore it makes sense to use a run-length encoding to store them, as
this commit does. Notice that the length 16 has to be treated specially
because there are arrays with more than 256 consecutive entries with
value 16 and because the length of the entries start to descend from
this length onward.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This has happened if the format changed midstream and if the new packet
is so small that it is instantaneously rejected: In this case the VLC
tables were for the new format, although the context says that they are
still the ones for the old format. It can also happen if the format
changed midstream and the allocation of the new tables fails. If the
next packet is a packet for the old format, the decoder thinks it
already has the correct VLC tables, leading to a segfault.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Don't needlessly copy an array around; don't create a table with
default symbols; and use smaller types to save stack space: The longest
code here is 16 bits, so one can store the codes in this type.
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
The current design, where
- proper init is called for the first per-thread context
- first thread's private data is copied into private data for all the
other threads
- a "fixup" function is called for all the other threads to e.g.
allocate dynamically allocated data
is very fragile and hard to follow, so it is abandoned. Instead, the
same init function is used to init each per-thread context. Where
necessary, AVCodecInternal.is_copy can be used to differentiate between
the first thread and the other ones (e.g. for decoding the extradata
just once).
