Works around assertion failure due to something that appears to be a
(minor) FFmpeg bug.

Version 2.5 fixed an API oddity, however it broke API compatibility,
at least with C++.  Disable the workaround when a libavformat version
is detected that is recent enough.

That attribute was uninitialized before, which could crash
libavformat.

See Debian bug 760669

In version 11, both ffmpeg and libav deprecate
AVCodecContext::codec_name.  The function avcodec_descriptor_get() has
been introduced long ago.

This corrects a major mistake from commit 724a59aa - there was one
small thing that commit was supposed to do, and it failed.
AV_TIME_BASE is not a seek flag.

Fixes potential nullptr dereference.

Map LogLevel::INFO to G_LOG_LEVEL_INFO, and LogLevel::DEFAULT to
G_LOG_LEVEL_MESSAGE.  Now client connect/disconnect message are only
logged on log_level "secure".

Prepare to migrate away from GLib.  Currently, we're still using GLib
as a backend.

Replaces GLib's GError.

FfmpegDecoderPlugin: Allocate the interleaved buffer as needed instead of using an arbitrary big constant.

Also, save a memcpy when FFmpeg outputs interleaved audio.

Fixes build with FFmpeg 2.0.

Now that even Debian stable has picked up version 0.8, we can safely
make this a requirement, and remove a lot of old cruft.

Only relevant for old ffmpeg versions.

AVFrame must be allocated with avcodec_alloc_frame().

This is the version present in Ubuntu Oneiric, the oldest distribution
with gcc 4.6.  Debian Squeeze is off target, because it has gcc 4.4,
which is unable to compile MPD anyway.

This commit drops all API compatibility hacks for older versions.

Hide the definition from C code, to prepare the transition to C++.