Same bug as in the previous commit.

When the data chunk size is not a multiple of the frame size, the last
partial frame lead to an endless loop.  We fix this by checking
chunk_sze>=frame instead of chunk_sze>0.  This way, the partial frame
is simply skipped.

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

Failure to read another chunk header is not fatal.  Continue to read
metadata.

Previously, MPD tried to slurp the whole song file, count the number
of frames and calculate the song duration from that.  That however is
extremely expensive for remote files, and will delay playback for a
long time.  Workaround: check only the first 128 frames and try to
extrapolate from here.  Fixes Mantis ticket 0004035.

Eliminate more duplicate code.

Don't bother to check for ADIF just because the stream is not
seekable.

Merge some duplicate code.

Eliminate some overhead when the caller doesn't need the buffer.

Checking the integer is faster, easier and more reliable.

.. instead of declaring a new constant.

Replaces the loop in sndfile_vio_read(), eliminating duplicate and
fragile code.

.. instead of InputStream::LockRead(). The former is cancellable.

Addresses Mantis ticket 0004015.

[mk: use decoder_read_full() only when needed, and a few formal
changes]

Works around WAV stream playback bug, because libaudiofile does not
like partial reads (Mantis 0004028).

Move code from the "mad" plugin.

Move code from the "mad" plugin.

.. instead of InputStream::LockRead(). The former is cancellable.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

Fixes missing song length on high-latency Opus files.

According to tests with 320 kbit/s opus files with 60ms packets, we
need to skip up to 29 kB.

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.