mxfmux: Add support for muxing A-Law audio

gst/mxf/mxfalaw.c

@@ -29,6 +29,7 @@
 #include <string.h>
 
 #include "mxfalaw.h"
+#include "mxfwrite.h"
 
 GST_DEBUG_CATEGORY_EXTERN (mxf_debug);
 #define GST_CAT_DEFAULT mxf_debug
@@ -138,8 +139,181 @@ static const MXFEssenceElementHandler mxf_alaw_essence_element_handler = {
   mxf_alaw_create_caps
 };
 
+typedef struct
+{
+  guint64 error;
+  gint rate, channels;
+  MXFFraction edit_rate;
+} ALawMappingData;
+
+static GstFlowReturn
+mxf_alaw_write_func (GstBuffer * buffer, GstCaps * caps, gpointer mapping_data,
+    GstAdapter * adapter, GstBuffer ** outbuf, gboolean flush)
+{
+  ALawMappingData *md = mapping_data;
+  guint bytes;
+
+  if (buffer) {
+    guint64 speu =
+        gst_util_uint64_scale (md->rate, md->edit_rate.d, md->edit_rate.n);
+
+    md->error += (GST_SECOND * md->edit_rate.d * md->rate) % (md->edit_rate.n);
+    if (md->error >= md->edit_rate.n) {
+      md->error = 0;
+      speu += 1;
+    }
+
+    bytes = speu * md->channels;
+
+    gst_adapter_push (adapter, buffer);
+    if (gst_adapter_available (adapter) >= bytes) {
+      *outbuf = gst_adapter_take_buffer (adapter, bytes);
+    }
+  } else if (flush && (bytes = gst_adapter_available (adapter))) {
+    *outbuf = gst_adapter_take_buffer (adapter, bytes);
+  }
+
+  return GST_FLOW_OK;
+}
+
+static const guint8 alaw_essence_container_ul[] = {
+  0x06, 0x0e, 0x2b, 0x34, 0x04, 0x01, 0x01, 0x03,
+  0x0d, 0x01, 0x03, 0x01, 0x02, 0x0a, 0x01, 0x00
+};
+
+static const MXFUL mxf_sound_essence_compression_alaw =
+    { {0x06, 0x0E, 0x2B, 0x34, 0x04, 0x01, 0x01, 0x03, 0x04, 0x02, 0x02, 0x02,
+    0x03, 0x01, 0x01, 0x00}
+};
+
+static MXFMetadataFileDescriptor *
+mxf_alaw_get_descriptor (GstPadTemplate * tmpl, GstCaps * caps,
+    MXFEssenceElementWriteFunc * handler, gpointer * mapping_data)
+{
+  MXFMetadataGenericSoundEssenceDescriptor *ret;
+  GstStructure *s;
+  ALawMappingData *md;
+  gint rate, channels;
+
+  s = gst_caps_get_structure (caps, 0);
+  if (strcmp (gst_structure_get_name (s), "audio/x-alaw") != 0)
+    return NULL;
+
+  if (!gst_structure_get_int (s, "rate", &rate) ||
+      !gst_structure_get_int (s, "channels", &channels))
+    return NULL;
+
+  ret = (MXFMetadataGenericSoundEssenceDescriptor *)
+      gst_mini_object_new (MXF_TYPE_METADATA_GENERIC_SOUND_ESSENCE_DESCRIPTOR);
+
+  memcpy (&ret->parent.essence_container, &alaw_essence_container_ul, 16);
+  memcpy (&ret->sound_essence_compression, &mxf_sound_essence_compression_alaw,
+      16);
+
+  mxf_metadata_generic_sound_essence_descriptor_from_caps (ret, caps);
+  *handler = mxf_alaw_write_func;
+
+  md = g_new0 (ALawMappingData, 1);
+  md->rate = rate;
+  md->channels = channels;
+  *mapping_data = md;
+
+  return (MXFMetadataFileDescriptor *) ret;
+}
+
+static void
+mxf_alaw_update_descriptor (MXFMetadataFileDescriptor * d, GstCaps * caps,
+    gpointer mapping_data, GstBuffer * buf)
+{
+  return;
+}
+
+static guint
+gst_greatest_common_divisor (guint a, guint b)
+{
+  while (b != 0) {
+    guint temp = a;
+
+    a = b;
+    b = temp % b;
+  }
+
+  return a;
+}
+
+static void
+mxf_alaw_get_edit_rate (MXFMetadataFileDescriptor * a, GstCaps * caps,
+    gpointer mapping_data, GstBuffer * buf, MXFMetadataSourcePackage * package,
+    MXFMetadataTimelineTrack * track, MXFFraction * edit_rate)
+{
+  guint i;
+  gdouble min = G_MAXDOUBLE;
+  MXFMetadataGenericSoundEssenceDescriptor *d =
+      MXF_METADATA_GENERIC_SOUND_ESSENCE_DESCRIPTOR (a);
+  ALawMappingData *md = mapping_data;
+
+  for (i = 0; i < package->parent.n_tracks; i++) {
+    MXFMetadataTimelineTrack *tmp;
+
+    if (!MXF_IS_METADATA_TIMELINE_TRACK (package->parent.tracks[i]) ||
+        package->parent.tracks[i] == (MXFMetadataTrack *) track)
+      continue;
+
+    tmp = MXF_METADATA_TIMELINE_TRACK (package->parent.tracks[i]);
+    if (((gdouble) tmp->edit_rate.n) / ((gdouble) tmp->edit_rate.d) < min) {
+      min = ((gdouble) tmp->edit_rate.n) / ((gdouble) tmp->edit_rate.d);
+      memcpy (edit_rate, &tmp->edit_rate, sizeof (MXFFraction));
+    }
+  }
+
+  if (min == G_MAXDOUBLE) {
+    guint32 nu, de;
+    guint gcd;
+
+    /* 50ms edit units */
+    nu = d->audio_sampling_rate.n;
+    de = d->audio_sampling_rate.d * 20;
+    gcd = gst_greatest_common_divisor (nu, de);
+    nu /= gcd;
+    de /= gcd;
+
+    (*edit_rate).n = nu;
+    (*edit_rate).d = de;
+  }
+
+  memcpy (&md->edit_rate, edit_rate, sizeof (MXFFraction));
+}
+
+static guint32
+mxf_alaw_get_track_number_template (MXFMetadataFileDescriptor * a,
+    GstCaps * caps, gpointer mapping_data)
+{
+  return (0x16 << 24) | (0x08 << 8);
+}
+
+static MXFEssenceElementWriter mxf_alaw_essence_element_writer = {
+  mxf_alaw_get_descriptor,
+  mxf_alaw_update_descriptor,
+  mxf_alaw_get_edit_rate,
+  mxf_alaw_get_track_number_template,
+  NULL,
+  {{0,}}
+};
+
+#define ALAW_CAPS \
+      "audio/x-alaw, " \
+      "rate = (int) [ 8000, 192000 ], " \
+      "channels = (int) [ 1, 2 ]"
+
 void
 mxf_alaw_init (void)
 {
   mxf_essence_element_handler_register (&mxf_alaw_essence_element_handler);
+
+  mxf_alaw_essence_element_writer.pad_template =
+      gst_pad_template_new ("alaw_audio_sink_%u", GST_PAD_SINK, GST_PAD_REQUEST,
+      gst_caps_from_string (ALAW_CAPS));
+  memcpy (&mxf_alaw_essence_element_writer.data_definition,
+      mxf_metadata_track_identifier_get (MXF_METADATA_TRACK_SOUND_ESSENCE), 16);
+  mxf_essence_element_writer_register (&mxf_alaw_essence_element_writer);
 }