added a reference audio decoder plugin

CVS patchset: 3154
CVS date: 2002/11/02 20:55:23

2 files changed, 337 insertions, 0 deletions

diff --git a/src/libxineadec/Makefile.am b/src/libxineadec/Makefile.am
index 03e0d8777..320f05b3b 100644
--- a/src/libxineadec/Makefile.am
+++ b/src/libxineadec/Makefile.am
@@ -2,6 +2,8 @@
 # the Makefile for the native xine audio decoders
 #
 
+EXTRA_DIST = fooaudio.c
+
 LIBTOOL = $(SHELL) $(top_builddir)/libtool-nofpic
 
 libdir = $(XINE_PLUGINDIR)
diff --git a/src/libxineadec/fooaudio.c b/src/libxineadec/fooaudio.c
new file mode 100644
index 000000000..a1805179d
--- /dev/null
+++ b/src/libxineadec/fooaudio.c
@@ -0,0 +1,335 @@
+/*
+ * Copyright (C) 2000-2001 the xine project
+ *
+ * This file is part of xine, a free video player.
+ *
+ * xine 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.
+ *
+ * xine 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA
+ *
+ * fooaudio.c: This is a reference audio decoder for the xine multimedia
+ * player. It really works too! It will output a continuous sine wave in
+ * place of the data it should actually send.
+ *
+ * $Id: fooaudio.c,v 1.1 2002/11/02 20:55:23 tmmm Exp $
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "xine_internal.h"
+#include "audio_out.h"
+#include "buffer.h"
+#include "xineutils.h"
+#include "bswap.h"
+
+/* math.h required for fooaudio sine wave generation */
+#include <math.h>
+
+#define AUDIOBUFSIZE 128*1024
+
+typedef struct {
+  audio_decoder_class_t   decoder_class;
+} fooaudio_class_t;
+
+typedef struct fooaudio_decoder_s {
+  audio_decoder_t  audio_decoder;
+
+  xine_stream_t    *stream;
+
+  int              sample_rate;       /* audio sample rate */
+  int              bits_per_sample;   /* bits/sample, usually 8 or 16 */
+  int              channels;          /* 1 or 2, usually */
+
+  int              output_open;       /* flag to indicate audio is ready */
+
+  unsigned char   *buf;               /* data accumulation buffer */
+  int              bufsize;           /* maximum size of buf */
+  int              size;              /* size of accumulated data in buf */
+
+  /* fooaudio-specific variables */
+  int64_t           last_pts;
+  unsigned int      iteration;
+
+} fooaudio_decoder_t;
+
+/**************************************************************************
+ * fooaudio specific decode functions
+ *************************************************************************/
+
+/**************************************************************************
+ * xine audio plugin functions
+ *************************************************************************/
+
+static void fooaudio_decode_data (audio_decoder_t *this_gen, buf_element_t *buf) {
+
+  fooaudio_decoder_t *this = (fooaudio_decoder_t *) this_gen;
+  audio_buffer_t *audio_buffer;
+  int i;
+  int64_t samples_to_generate;
+  int samples_to_send;
+
+  if (buf->decoder_flags & BUF_FLAG_HEADER) {
+
+    /* When the engine sends a BUF_FLAG_HEADER flag, it is time to initialize
+     * the decoder. The buffer element type has 4 decoder_info fields,
+     * 0..3. Field 1 is the sample rate. Field 2 is the bits/sample. Field
+     * 3 is the number of channels. */
+    this->sample_rate = buf->decoder_info[1];
+    this->bits_per_sample = buf->decoder_info[2];
+    this->channels = buf->decoder_info[3];
+
+    /* initialize the data accumulation buffer */
+    this->buf = xine_xmalloc(AUDIOBUFSIZE);
+    this->bufsize = AUDIOBUFSIZE;
+    this->size = 0;
+
+    /* peform any other required initialization */
+    this->last_pts = -1;
+    this->iteration = 0;
+
+    return;
+  }
+
+  /* if the audio output is not open yet, open the audio output */
+#warning: Audio output is hardcoded to mono 16-bit PCM
+  if (!this->output_open) {
+    this->output_open = this->stream->audio_out->open(
+      this->stream->audio_out,
+/*      this->bits_per_sample, */
+      16,
+      this->sample_rate,
+/*      (this->channels == 2) ? AO_CAP_MODE_STEREO : AO_CAP_MODE_MONO);*/
+      AO_CAP_MODE_MONO);
+  }
+
+  /* if the audio still isn't open, do not go any further with the decode */
+  if (!this->output_open)
+    return;
+
+  /* accumulate the data passed through the buffer element type; increase
+   * the accumulator buffer size as necessary */
+  if( this->size + buf->size > this->bufsize ) {
+    this->bufsize = this->size + 2 * buf->size;
+    printf("fooaudio: increasing source buffer to %d to avoid overflow.\n",
+      this->bufsize);
+    this->buf = realloc( this->buf, this->bufsize );
+  }
+  xine_fast_memcpy (&this->buf[this->size], buf->content, buf->size);
+  this->size += buf->size;
+
+  /* When a buffer element type has the BUF_FLAG_FRAME_END flag set, it is
+   * time to decode the data in the buffer. */
+  if (buf->decoder_flags & BUF_FLAG_FRAME_END)  {
+
+    /* This is where the real meat of the audio decoder is implemented.
+     * The general strategy is to decode the data in the accumulation buffer
+     * into raw PCM data and then dispatch the PCM to the engine in smaller
+     * buffers. What follows in the inside of this scope is the meat of
+     * this particular audio decoder. */
+
+    /* Operation of the fooaudio decoder:
+     * This decoder generates a continuous sine pattern based on the pts
+     * values sent by the xine engine. Two pts values are needed to know
+     * how long to make the audio. Thus, If this is the first frame or
+     * a seek has occurred (indicated by this->last_pts = -1), 
+     * log the pts but do not create any audio. 
+     *
+     * When a valid pts delta is generated, create n audio samples, where
+     * n is given as:
+     *
+     *       n          pts delta
+     *  -----------  =  ---------  =>  n = (pts delta * sample rate) / 90000
+     *  sample rate       90000
+     *
+     */
+
+    if (this->last_pts != -1) {
+
+      /* no real reason to set this variable to 0 first; I just wanted the
+       * novelty of using all 4 basic arithmetic ops in a row (+ - * /) */
+      samples_to_generate = 0;
+      samples_to_generate += buf->pts;
+      samples_to_generate -= this->last_pts;
+      samples_to_generate *= this->sample_rate;
+      samples_to_generate /= 90000;
+
+      /* save the pts now since it will likely be trashed later */
+      this->last_pts = buf->pts;
+
+      while (samples_to_generate) {
+
+        /* get an audio buffer */
+        audio_buffer = this->stream->audio_out->get_buffer (this->stream->audio_out);
+        if (audio_buffer->mem_size == 0) {
+          printf ("fooaudio: Help! Allocated audio buffer with nothing in it!\n");
+          return;
+        }
+
+        /* samples_to_generate is a sample count; mem_size is a byte count */
+        if (samples_to_generate > audio_buffer->mem_size / 2)
+          samples_to_send = audio_buffer->mem_size / 2;
+        else
+          samples_to_send = samples_to_generate;
+        samples_to_generate -= samples_to_send;
+
+#define WAVE_HZ 300
+        /* fill up the samples in the buffer */
+        for (i = 0; i < samples_to_send; i++)
+          audio_buffer->mem[i] = 
+            (short)(sin(2 * M_PI * this->iteration++ / WAVE_HZ) * 32767);
+
+        /* final prep for audio buffer dispatch */
+        audio_buffer->num_frames = samples_to_send;
+        audio_buffer->vpts = buf->pts;
+        buf->pts = 0;  /* only first buffer gets the real pts */
+        this->stream->audio_out->put_buffer (this->stream->audio_out, audio_buffer);
+
+      }
+    } else {
+      /* log the pts for the next time */
+      this->last_pts = buf->pts;
+    }
+
+    /* reset data accumulation buffer */
+    this->size = 0;
+  }
+}
+
+/* This function resets the state of the audio decoder. This usually
+ * entails resetting the data accumulation buffer. */
+static void fooaudio_reset (audio_decoder_t *this_gen) {
+
+  fooaudio_decoder_t *this = (fooaudio_decoder_t *) this_gen;
+
+  this->size = 0;
+
+  /* this is specific to fooaudio */
+  this->last_pts = -1;
+}
+
+/* This function closes the audio output and frees the private audio decoder
+ * structure. */
+static void fooaudio_dispose (audio_decoder_t *this_gen) {
+
+  fooaudio_decoder_t *this = (fooaudio_decoder_t *) this_gen;
+
+  /* close the audio output */
+  if (this->output_open)
+    this->stream->audio_out->close (this->stream->audio_out);
+  this->output_open = 0;
+
+  /* free anything that was allocated during operation */
+  free(this->buf);
+  free(this);
+}
+
+/* This function allocates, initializes, and returns a private audio
+ * decoder structure. */
+static audio_decoder_t *open_plugin (audio_decoder_class_t *class_gen, xine_stream_t *stream) {
+
+  fooaudio_decoder_t *this ;
+
+  this = (fooaudio_decoder_t *) malloc (sizeof (fooaudio_decoder_t));
+
+  /* connect the member functions */
+  this->audio_decoder.decode_data         = fooaudio_decode_data;
+  this->audio_decoder.reset               = fooaudio_reset;
+  this->audio_decoder.dispose             = fooaudio_dispose;
+
+  /* connect the stream */
+  this->stream = stream;
+
+  /* audio output is not open at the start */
+  this->output_open = 0;
+
+  /* initialize the basic audio parameters */
+  this->channels = 0;
+  this->sample_rate = 0;
+  this->bits_per_sample = 0;
+
+  /* initialize the data accumulation buffer */
+  this->buf = NULL;
+  this->bufsize = 0;
+  this->size = 0;
+
+  /* return the newly-initialized audio decoder */
+  return &this->audio_decoder;
+}
+
+/* This function returns a brief string that describes (usually with the
+ * decoder's most basic name) the audio decoder plugin. */
+static char *get_identifier (audio_decoder_class_t *this) {
+  return "fooaudio";
+}
+
+/* This function returns a slightly longer string describing the audio
+ * decoder plugin. */
+static char *get_description (audio_decoder_class_t *this) {
+  return "fooaudio: reference xine audio decoder plugin";
+}
+
+/* This function frees the audio decoder class and any other memory that was
+ * allocated. */
+static void dispose_class (audio_decoder_class_t *this_gen) {
+
+  fooaudio_class_t *this = (fooaudio_class_t *)this_gen;
+
+  free (this);
+}
+
+/* This function allocates a private audio decoder class and initializes 
+ * the class's member functions. */
+static void *init_plugin (xine_t *xine, void *data) {
+
+  fooaudio_class_t *this ;
+
+  this = (fooaudio_class_t *) malloc (sizeof (fooaudio_class_t));
+
+  this->decoder_class.open_plugin     = open_plugin;
+  this->decoder_class.get_identifier  = get_identifier;
+  this->decoder_class.get_description = get_description;
+  this->decoder_class.dispose         = dispose_class;
+
+  return this;
+}
+
+/* This is a list of all of the internal xine audio buffer types that 
+ * this decoder is able to handle. Check src/xine-engine/buffer.h for a
+ * list of valid buffer types (and add a new one if the one you need does
+ * not exist). Terminate the list with a 0. */
+static uint32_t audio_types[] = { 
+  /* BUF_AUDIO_FOO, */
+  0
+};
+
+/* This data structure combines the list of supported xine buffer types and
+ * the priority that the plugin should be given with respect to other
+ * plugins that handle the same buffer type. A plugin with priority (n+1) 
+ * will be used instead of a plugin with priority (n). */
+static decoder_info_t dec_info_audio = {
+  audio_types,         /* supported types */
+  5                    /* priority        */
+};
+
+/* The plugin catalog entry. This is the only information that this plugin
+ * will export to the public. */
+plugin_info_t xine_plugin_info[] = {
+  /* { type, API version, "name", version, special_info, init_function }, */
+  { PLUGIN_AUDIO_DECODER, 10, "fooaudio", XINE_VERSION_CODE, &dec_info_audio, &init_plugin },
+  { PLUGIN_NONE, 0, "", 0, NULL, NULL }
+};
+