Open decoders first, next encoders. This makes sure that that
subtitle_header is always set properly, without relying on
avformat_find_stream_info() setting it.

Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.

In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.

There are multiple important problems with this approach:
    - the fields in AVCodecContext are in general one of
        * stream parameters
        * codec options
        * codec state
      However, it's not clear which ones are which. It is consequently
      unclear which fields are a demuxer allowed to set or a muxer allowed to
      read. This leads to erratic behaviour depending on whether decoding or
      encoding is being performed or not (and whether it uses the AVStream
      embedded codec context).
    - various synchronization issues arising from the fact that the same
      context is used by several different APIs (muxers/demuxers,
      parsers, bitstream filters and encoders/decoders) simultaneously, with
      there being no clear rules for who can modify what and the different
      processes being typically delayed with respect to each other.
    - avformat_find_stream_info() making it necessary to support opening
      and closing a single codec context multiple times, thus
      complicating the semantics of freeing various allocated objects in the
      codec context.

Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.

This API is intended to allow passing around codec parameters without
using full AVCodecContext (which also contains codec options and
encoder/decoder state).

Some optimized functions reference optimized symbols, so the functions
must be explicitly disabled when those symbols are unavailable.

Some files may be missing for valid reasons, e.g. on compile failure.

Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Marton Balint <cus@passwd.hu>

Sample-Id: asan_heap-uaf_3660f67_757_cov_1257014655_Hi422FR1_SONY_A.jsv
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

First check the context, then check internal option. Drop the ! typo.
Introduced in 60f0fde3.

Should make the default behaviour safer for careless callers that open
random untrusted files.

Bug-Id: CVE-2016-1897
Bug-Id: CVE-2016-1898

This way, the decisions about which protocols are available for use in
any given situations can be delegated to the caller.

It will be useful in the following commits.

Disallow other code to touch it directly, now it's only accessible
through a blacklisting/whitelisting function.

It needs to access the list of protocols directly, so it more properly
belongs there.

It's a more appropriate place for it.

Instead of a linked list constructed at av_register_all(), store them
in a constant array of pointers.

Since no registration is necessary now, this removes some global state
from lavf. This will also allow the urlprotocol layer caller to limit
the available protocols in a simple and flexible way in the following
commits.

They are only written to, never read.

Now all IO should go through the IO callbacks and be interceptable by
the caller.

There is no real reason to treat them differently.

avio_close() can only be called on AVIOContexts created by avio_open(2).

It will in general not be available. Use block_align if known or fall
back to av_get_audio_frame_duration().

Reported-By: Maxim Koitsov <maksbotan@gentoo.org>

Some muxer might or might not fit incomplete mp3 frames in
their packets.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

Some muxer might or might not fit incomplete mp3 frames in
their packets.

Bug-Id: 899

CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

This reverts commits 2edc7187, a2bb771a, 21c750f2, 8e7bea6d.

The WTV demuxer depends on large parts of the MPEG-TS demuxer internals
anyway and fails to build without it.