Without any optimization flags, MSVC does no dead code elimination (DCE) at
all, even for the most trivial cases. DCE is a prerequisite for building libav
correctly, otherwise there are undefined references to functions for other
architectures and disabled components.

-O1 is the minimal optimization flag for MSVC that does include DCE.

When receiving fragmented packets, the first packet declares the size,
and the later ones normally are small follow-on packets that don't repeat
the size and the other header fields. But technically, the later fragments
also can have a full header, declaring a different size than the previous
packet.

If the follow-on packet declares a larger size than the initial one, we
could end up writing outside of the allocation.

This fixes out of bounds writes.
Found-by: Paul Cher <paulcher@icloud.com>
Reviewed-by: Paul Cher <paulcher@icloud.com>

CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>

This seems to have been added by mistake in 11de006b, by not
noticing the negation for the existing condition. This block does
not contain any code that accesses the codec field in AVStream.

This function is meant to serve as a complement to compute_pkt_fields2,
which is guarded by FF_API_COMPUTE_PKT_FIELDS2 && FF_API_LAVF_AVCTX.
Signed-off-by: Martin Storsjö <martin@martin.st>

The former is not an official pseudo instruction although gas and llvm's
internal assembler support it. Fixes a build error with xcode 6.2
reported by Memphiz on github.

There is no point in keeping the two separate.

Also move #includes into canonical order where appropriate.

This is more consistent and fixes compilation with clang.

This improves commit 59c70227.

In ff_thread_report_progress(), the fast code path can load
progress[field] with the relaxed memory order, and the slow code path
can store progress[field] with the release memory order. These changes
are mainly intended to avoid confusion when one inspects the source code.
They are unlikely to have measurable performance improvement.

ff_thread_report_progress() and ff_thread_await_progress() form a pair.
ff_thread_await_progress() reads progress[field] with the acquire memory
order (in the fast code path). Therefore, one expects to see
ff_thread_report_progress() write progress[field] with the matching
release memory order.

In the fast code path in ff_thread_report_progress(), the atomic load of
progress[field] doesn't need the acquire memory order because the
calling thread is trying to make the data it just decoded visible to the
other threads, rather than trying to read the data decoded by other
threads.

In ff_thread_get_buffer(), initialize progress[0] and progress[1] using
atomic_init().
Signed-off-by: Wan-Teh Chang <wtc@google.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>

This could happen when there was a frame number gap and frame threading was used.
Debugging-by: Ronald S. Bultje <rsbultje@gmail.com>
Debugging-by: Justin Ruggles <justin.ruggles@gmail.com>
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

CC:libav-stable@libav.org
Signed-off-by: Anton Khirnov <anton@khirnov.net>

This makes sure ff_get_format() does not get called unnecessarily from
update_thread_context().

It is more natural for this codec and allows to avoid awkward constructs
like "consuming 0 bytes from input". Also, keep a reference to the input
packet to avoid unnecessary copying.

Significantly increases the efficiency of frame threading, since
individual frames in a superframe can now be decoded in parallel.

Partially based on code by Ronald S. Bultje <rsbultje@gmail.com>.

Drop the internal manual conversion from the MP4 format to Annex B.

Currently, the new decoding API is pretty much just a wrapper around the
old deprecated one. This is problematic, since it interferes with making
full use of the flexibility added by the new API. The old API should
also be removed at some future point.

Reorganize the code so that the new send_packet/receive_frame functions
call the actual decoding directly and change the old deprecated
avcodec_decode_* functions into wrappers around the new API.

The new internal API for decoders is now changing as well. Before this
commit, it mirrors the public API, so the decoders need to implement
send_packet() and receive_frame() callbacks. This turns out to require
awkward constructs in both the decoders and the generic code. After this
commit, the decoders only implement the receive_frame() callback and
call a new internal function, ff_decode_get_packet() to obtain input
data, in the same manner to how the bitstream filters now work.

avcodec will now always make a reference to the input packet, which means
that non-refcounted input packets will be copied. Keeping the previous
behaviour, where this copy could sometimes be avoided, would make the
code significantly more complex and fragile for only dubious gains,
since packets are typically small and everyone who cares about
performance should use refcounted packets anyway.

The current code stores a pointer to the packet passed to the decoder,
which is then used during get_buffer() for timestamps and side data
passthrough. However, since this is a pointer to user data which we do
not own, storing it is potentially dangerous. It is also ill defined for
the new decoding API with split input/output.

Fix this problem by making an explicit internally owned copy of the
packet properties.

It is useful for testing/debugging and will also be used as the default
filter in the following commit adding pre-decode filtering to avoid
having a separate non-filtered codepath.

This partially reverts commit ac648bb8.

Signed-off-by: Diego Biurrun <diego@biurrun.de>

The feature has outlived is usefulness and complicates the code.

Same issue as 17a0f948.

This is required to make certain math defines visible on modern Cygwin.

This makes naming more consistent and simplifies extralibs-related changes.

This is more in line with the other related variable names.

These components should depend on the availability of the respective
libraries, not just on the availability of the respective headers.

These are taken care of more correctly by the library checks.

That header should only be included in the special bits that use X11 code.