encoder/lame: dynamic output buffer

Makefile.am

@@ -268,6 +268,7 @@ endif
 # Generic utility library
 
 libutil_a_SOURCES = \
+	src/util/AllocatedArray.hxx \
 	src/util/StringUtil.cxx src/util/StringUtil.hxx \
 	src/util/Tokenizer.cxx src/util/Tokenizer.hxx \
 	src/util/UriUtil.cxx src/util/UriUtil.hxx \

src/encoder/LameEncoderPlugin.cxx

@@ -21,6 +21,8 @@
 #include "LameEncoderPlugin.hxx"
 #include "EncoderAPI.hxx"
 #include "AudioFormat.hxx"
+#include "util/AllocatedArray.hxx"
+#include "util/Manual.hxx"
 
 #include <lame/lame.h>
 
@@ -38,7 +40,7 @@ struct LameEncoder final {
 
 	lame_global_flags *gfp;
 
-	unsigned char output_buffer[32768];
+	Manual<AllocatedArray<unsigned char>> output_buffer;
 	size_t output_buffer_length, output_buffer_position;
 
 	LameEncoder():encoder(lame_encoder_plugin) {}
@@ -209,6 +211,8 @@ lame_encoder_open(Encoder *_encoder, AudioFormat &audio_format,
 		return false;
 	}
 
+	encoder->output_buffer.Construct();
+
 	encoder->output_buffer_length = 0;
 	encoder->output_buffer_position = 0;
 
@@ -221,6 +225,7 @@ lame_encoder_close(Encoder *_encoder)
 	LameEncoder *encoder = (LameEncoder *)_encoder;
 
 	lame_close(encoder->gfp);
+	encoder->output_buffer.Destruct();
 }
 
 static bool
@@ -236,14 +241,22 @@ lame_encoder_write(Encoder *_encoder,
 
 	const unsigned num_frames =
 		length / encoder->audio_format.GetFrameSize();
+	const unsigned num_samples =
+		length / encoder->audio_format.GetSampleSize();
+
+	/* worst-case formula according to LAME documentation */
+	const size_t output_buffer_size = 5 * num_samples / 4 + 7200;
+	encoder->output_buffer->GrowDiscard(output_buffer_size);
+
+	const auto output_buffer = encoder->output_buffer->begin();
 
 	/* this is for only 16-bit audio */
 
 	int bytes_out = lame_encode_buffer_interleaved(encoder->gfp,
 						       const_cast<short *>(src),
 						       num_frames,
-						       encoder->output_buffer,
-						       sizeof(encoder->output_buffer));
+						       output_buffer,
+						       output_buffer_size);
 
 	if (bytes_out < 0) {
 		g_set_error(error, lame_encoder_quark(), 0,
@@ -269,7 +282,8 @@ lame_encoder_read(Encoder *_encoder, void *dest, size_t length)
 	if (length > remainning)
 		length = remainning;
 
-	memcpy(dest, encoder->output_buffer + encoder->output_buffer_position,
+	memcpy(dest,
+	       encoder->output_buffer->begin() + encoder->output_buffer_position,
 	       length);
 
 	encoder->output_buffer_position += length;

src/util/AllocatedArray.hxx

@@ -0,0 +1,189 @@
+/*
+ * Copyright (C) 2010 Max Kellermann <max@duempel.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef ALLOCATED_ARRAY_HPP
+#define ALLOCATED_ARRAY_HPP
+
+#include "gcc.h"
+
+#include <assert.h>
+#include <algorithm>
+
+/**
+ * An array allocated on the heap with a length determined at runtime.
+ */
+template<class T>
+class AllocatedArray {
+public:
+  typedef size_t size_type;
+
+protected:
+  size_type the_size;
+  T *restrict data;
+
+public:
+  typedef T *iterator;
+  typedef const T *const_iterator;
+
+public:
+  constexpr AllocatedArray():the_size(0), data(nullptr) {}
+
+  explicit AllocatedArray(size_type _size)
+    :the_size(_size), data(new T[the_size]) {
+    assert(size() == 0 || data != nullptr);
+  }
+
+  explicit AllocatedArray(const AllocatedArray &other)
+    :the_size(other.size()), data(new T[the_size]) {
+    assert(size() == 0 || data != nullptr);
+    assert(other.size() == 0 || other.data != nullptr);
+
+    std::copy(other.data, other.data + the_size, data);
+  }
+
+  explicit AllocatedArray(AllocatedArray &&other)
+    :the_size(other.the_size), data(other.data) {
+    other.the_size = 0;
+    other.data = nullptr;
+  }
+
+  ~AllocatedArray() {
+    delete[] data;
+  }
+
+  AllocatedArray &operator=(const AllocatedArray &other) {
+    assert(size() == 0 || data != nullptr);
+    assert(other.size() == 0 || other.data != nullptr);
+
+    if (&other == this)
+      return *this;
+
+    ResizeDiscard(other.size());
+    std::copy(other.begin(), other.end(), data);
+    return *this;
+  }
+
+  AllocatedArray &operator=(AllocatedArray &&other) {
+    std::swap(the_size, other.the_size);
+    std::swap(data, other.data);
+    return *this;
+  }
+
+  /**
+   * Returns true if no memory was allocated so far.
+   */
+  constexpr bool empty() const {
+    return the_size == 0;
+  }
+
+  /**
+   * Returns the number of allocated elements.
+   */
+  constexpr size_type size() const {
+    return the_size;
+  }
+
+  /**
+   * Returns one element.  No bounds checking.
+   */
+  T &operator[](size_type i) {
+    assert(i < size());
+
+    return data[i];
+  }
+
+  /**
+   * Returns one constant element.  No bounds checking.
+   */
+  const T &operator[](size_type i) const {
+    assert(i < size());
+
+    return data[i];
+  }
+
+  iterator begin() {
+    return data;
+  }
+
+  constexpr const_iterator begin() const {
+    return data;
+  }
+
+  iterator end() {
+    return data + the_size;
+  }
+
+  constexpr const_iterator end() const {
+    return data + the_size;
+  }
+
+  /**
+   * Resizes the array, discarding old data.
+   */
+  void ResizeDiscard(size_type _size) {
+    if (_size == the_size)
+      return;
+
+    delete[] data;
+    the_size = _size;
+    data = new T[the_size];
+
+    assert(size() == 0 || data != nullptr);
+  }
+
+  /**
+   * Grows the array to the specified size, discarding old data.
+   * Similar to ResizeDiscard(), but will never shrink the array to
+   * avoid expensive heap operations.
+   */
+  void GrowDiscard(size_type _size) {
+    if (_size > the_size)
+      ResizeDiscard(_size);
+  }
+
+  /**
+   * Grows the array to the specified size, preserving the value of a
+   * range of elements, starting from the beginning.
+   */
+  void GrowPreserve(size_type _size, size_type preserve) {
+    if (_size <= the_size)
+      return;
+
+    T *new_data = new T[_size];
+    assert(_size == 0 || new_data != nullptr);
+
+    std::move(data, data + preserve, new_data);
+
+    delete[] data;
+    data = new_data;
+    the_size = _size;
+  }
+};
+
+#endif