This commit introduces a new AVPacket side data type:
AV_PKT_DATA_STRINGS_METADATA. Its main goal is to provide a way to
transmit the metadata from the AVFilterBufferRef up to the AVFrame. This
is at the moment "only" useful for lavfi input from libavdevice:
lavd/lavfi only outputs packets, and the metadata from the buffer ref
kept in its context needs to be transmitted from the packet to the frame
by the decoders. The buffer ref can be destroyed at any time (along with
the metadata), and a duplication of the AVPacket needs to duplicate the
metadata as well, so the choice of using the side data to store them was
selected.

Making sure lavd/lavfi raises the metadata is useful to allow tools like
ffprobe to access the filters metadata (it is at the moment the only
way); ffprobe will now automatically show the AVFrame metadata in any
customizable output format for users. API users will also be able to
access the AVFrame->metadata pointer the same way ffprobe does
(av_frame_get_metadata).

All the changes are done in this single commit to avoid some memory
leaks: for instances, the changes in lavfi/avcodec.c are meant to
duplicate the metadata from the buffer ref into the AVFrame. Unless we
have an internal way of freeing the AVFrame->metadata automatically, it
will leak in most of the user apps. To fix this problem, we introduce
AVCodecContext->metadata and link avctx->metadata to the current
frame->metadata and free it at each decode frame call (and in the codec
closing callback for the last one). But doing this also means to update
the way the tiff decoder already handles the AVFrame->metadata (it's the
only one decoder with frame metadata at the moment), by making sure it
is not trying to free a pointer already freed by the lavc internals.

The lavfi/avcodec.c buffer ref code is based on an old Thomas Kühnel
work, the rest of the code belongs to the commit author.

Signed-off-by: Thomas Kühnel <kuehnelth@googlemail.com>
Signed-off-by: Clément Bœsch <ubitux@gmail.com>

Decrease confusion.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

Factorize.

Fix crash in case frame is not defined (e.g. with muxing out.wav).

The API was never changed since 2003. Replace with a comment about the
performed operation.

Fixes Ticket1801
Based on suggestion from AztecC
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Make the filter accept named options for the first argument, and update
documentation accordingly.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Signed-off-by: rogerdpack <rogerpack2005@gmail.com>

Signed-off-by: rogerdpack <rogerpack2005@gmail.com>

Signed-off-by: rogerdpack <rogerpack2005@gmail.com>

Signed-off-by: rogerdpack <rogerpack2005@gmail.com>

Based on libcompface code by James Ashton <James.Ashton@anu.edu.au>, and
relicensed to LGPL with the author's consent.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

The native tags will be used when available.

Make av_pix_fmt_descriptors table static on next major bump.

Making the table public is dangerous, since the caller has no way to
know how large it actually is. It also prevents adding new fields to
AVPixFmtDescriptor without a major bump.

The current API where the plain size is exposed is not of much
use - in most cases it is allocated dynamically anyway.

If allocated e.g. on the stack via an uint8_t array, there's no
guarantee that the struct's members are aligned properly (unless
the array is overallocated and the opaque pointer within it
manually aligned to some unspecified alignment).

Signed-off-by: Martin Storsjö <martin@martin.st>

URLProtocols are private and custom AVIOContexts are a simple and
easier solution for most of the situations.

It has not worked for anything other than fringe codecs (asv1/2, mdec,
mjpeg[b]) since about 2003 and nobody ever noticed or complained. This
sufficiently proves that there are no users of this option who have a
clue of what they are doing, so it is completely useless.

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Signed-off-by: Mans Rullgard <mans@mansr.com>

The tag @table expects @item to mark entries.

Signed-off-by: Paul B Mahol <onemda@gmail.com>

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

Fixes ticket #1354