decoder/ffmpeg: move code to lib/ffmpeg/Interleave.cxx

To be reused by the FFmpeg filter plugin.

src/lib/ffmpeg/Interleave.cxx

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2003-2020 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "Interleave.hxx"
+#include "Buffer.hxx"
+#include "Error.hxx"
+#include "pcm/Interleave.hxx"
+#include "util/ConstBuffer.hxx"
+
+extern "C" {
+#include <libavutil/frame.h>
+}
+
+#include <cassert>
+#include <new> // for std::bad_alloc
+
+namespace Ffmpeg {
+
+ConstBuffer<void>
+InterleaveFrame(const AVFrame &frame, FfmpegBuffer &buffer)
+{
+	assert(frame.nb_samples > 0);
+
+	const AVSampleFormat format = AVSampleFormat(frame.format);
+	const unsigned channels = frame.channels;
+	const std::size_t n_frames = frame.nb_samples;
+
+	int plane_size;
+	const int data_size =
+		av_samples_get_buffer_size(&plane_size, channels,
+					   n_frames, format, 1);
+	assert(data_size != 0);
+	if (data_size < 0)
+		throw MakeFfmpegError(data_size);
+
+	void *output_buffer;
+	if (av_sample_fmt_is_planar(format) && channels > 1) {
+		output_buffer = buffer.GetT<uint8_t>(data_size);
+		if (output_buffer == nullptr)
+			/* Not enough memory - shouldn't happen */
+			throw std::bad_alloc();
+
+		PcmInterleave(output_buffer,
+			      ConstBuffer<const void *>((const void *const*)frame.extended_data,
+							channels),
+			      n_frames,
+			      av_get_bytes_per_sample(format));
+	} else {
+		output_buffer = frame.extended_data[0];
+	}
+
+	return { output_buffer, (size_t)data_size };
+}
+
+} // namespace Ffmpeg

src/lib/ffmpeg/Interleave.hxx

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2003-2020 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_FFMPEG_INTERLEAVE_HXX
+#define MPD_FFMPEG_INTERLEAVE_HXX
+
+struct AVFrame;
+template<typename T> struct ConstBuffer;
+class FfmpegBuffer;
+
+namespace Ffmpeg {
+
+/**
+ * Return interleaved data from the given non-empty #AVFrame.  If the
+ * data is planar, then the data is copied to a buffer.
+ *
+ * Throws on error.
+ */
+ConstBuffer<void>
+InterleaveFrame(const AVFrame &frame, FfmpegBuffer &buffer);
+
+} // namespace Ffmpeg
+
+#endif

src/lib/ffmpeg/meson.build

@@ -26,6 +26,7 @@ endif
 ffmpeg = static_library(
   'ffmpeg',
   'Init.cxx',
+  'Interleave.cxx',
   'LogError.cxx',
   'LogCallback.cxx',
   'Error.cxx',