replaygain: fix gain sign decoding

The gain sign was incorrectly decoded: since the FFSIGN() macro treats 0 as
negative, gain values starting with "0." were always decoded as negative.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
replaygain: correctly parse peak values

According to the ReplayGain spec, the peak amplitude may overflow and may result
in peak amplitude values greater than 1.0 with psychoacoustically coded audio,
such as MP3. Fully compliant decoders must allow peak overflows.

Additionally, having peak values in the 0<->UINT32_MAX scale makes it more
difficult for applications to actually use the peak values (e.g. when
implementing clipping prevention) since values have to be rescaled down.

This patch corrects the peak parsing by removing the rescaling of the decoded
values between 0 and UINT32_MAX and the 1.0 upper limit.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
flacdec: export replaygain tags from Vorbis comments

Signed-off-by: Anton Khirnov <anton@khirnov.net>
lavu/opt: validate range before dereference

This change make error handling simplier.
av_opt_freep_ranges may be called when some ranges are NULL,
for example after memory allocation fail.

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
x86/synth_filter: remove the main loop when it's not needed

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '25b6837f7cacd691b19cbc12b9dad1ce84a318a1'

* commit '25b6837f7cacd691b19cbc12b9dad1ce84a318a1':
  replaygain: fix gain sign decoding

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '8542f9c4f17125d483c40c0c5723842f1c982f81'

* commit '8542f9c4f17125d483c40c0c5723842f1c982f81':
  replaygain: correctly parse peak values

Conflicts:
	libavutil/version.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '1d55f8d5f6f2cd74fa27170e2be37a72441d9202'

* commit '1d55f8d5f6f2cd74fa27170e2be37a72441d9202':
  flacdec: export replaygain tags from Vorbis comments

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