mpegtsmux: Expose bitrate property

This allows outputting a Transport Stream with a constant bitrate,
by inserting null packets.

gst/mpegtsmux/mpegtsmux.c

@@ -115,7 +115,8 @@ enum
   PROP_PAT_INTERVAL,
   PROP_PMT_INTERVAL,
   PROP_ALIGNMENT,
-  PROP_SI_INTERVAL
+  PROP_SI_INTERVAL,
+  PROP_BITRATE,
 };
 
 #define MPEGTSMUX_DEFAULT_ALIGNMENT    -1
@@ -305,6 +306,13 @@ mpegtsmux_class_init (MpegTsMuxClass * klass)
           "Set the interval (in ticks of the 90kHz clock) for writing out the Service"
           "Information tables", 1, G_MAXUINT, TSMUX_DEFAULT_SI_INTERVAL,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_BITRATE,
+      g_param_spec_uint64 ("bitrate", "Bitrate (in bits per second)",
+          "Set the target bitrate, will insert null packets as padding "
+          " to achieve multiplex-wide constant bitrate",
+          0, G_MAXUINT64, TSMUX_DEFAULT_BITRATE,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
 }
 
 static void
@@ -338,6 +346,7 @@ mpegtsmux_init (MpegTsMux * mux)
   mux->si_interval = TSMUX_DEFAULT_SI_INTERVAL;
   mux->prog_map = NULL;
   mux->alignment = MPEGTSMUX_DEFAULT_ALIGNMENT;
+  mux->bitrate = TSMUX_DEFAULT_BITRATE;
 
   /* initial state */
   mpegtsmux_reset (mux, TRUE);
@@ -511,6 +520,11 @@ gst_mpegtsmux_set_property (GObject * object, guint prop_id,
       mux->si_interval = g_value_get_uint (value);
       tsmux_set_si_interval (mux->tsmux, mux->si_interval);
       break;
+    case PROP_BITRATE:
+      mux->bitrate = g_value_get_uint64 (value);
+      if (mux->tsmux)
+        tsmux_set_bitrate (mux->tsmux, mux->bitrate);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -542,6 +556,9 @@ gst_mpegtsmux_get_property (GObject * object, guint prop_id,
     case PROP_SI_INTERVAL:
       g_value_set_uint (value, mux->si_interval);
       break;
+    case PROP_BITRATE:
+      g_value_set_uint64 (value, mux->bitrate);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;

gst/mpegtsmux/mpegtsmux.h

@@ -139,6 +139,7 @@ struct MpegTsMux {
   guint pmt_interval;
   gint alignment;
   guint si_interval;
+  guint64 bitrate;
 
   /* state */
   gboolean first;

gst/mpegtsmux/tsmux/tsmux.c

@@ -634,6 +634,8 @@ tsmux_packet_out (TsMux * mux, GstBuffer * buf, gint64 pcr)
     return TRUE;
   }
 
+  mux->n_bytes += gst_buffer_get_size (buf);
+
   return mux->write_func (buf, mux->write_func_data, pcr);
 }
 
@@ -1019,6 +1021,67 @@ tsmux_write_si (TsMux * mux)
 
 }
 
+static void
+tsmux_write_null_ts_header (guint8 * buf)
+{
+  *buf++ = TSMUX_SYNC_BYTE;
+  *buf++ = 0x1f;
+  *buf++ = 0xff;
+  *buf++ = 0x10;
+}
+
+static gboolean
+pad_stream (TsMux * mux, TsMuxStream * stream, gint64 cur_ts)
+{
+  guint64 bitrate;
+  GstBuffer *buf = NULL;
+  GstMapInfo map;
+  gboolean ret = TRUE;
+
+  do {
+    if (GST_CLOCK_STIME_IS_VALID (cur_ts)) {
+      GstClockTimeDiff diff;
+
+      if (!GST_CLOCK_STIME_IS_VALID (stream->first_ts))
+        stream->first_ts = cur_ts;
+
+      diff = GST_CLOCK_DIFF (stream->first_ts, cur_ts);
+
+      if (diff) {
+        bitrate =
+            gst_util_uint64_scale (mux->n_bytes * 8, TSMUX_CLOCK_FREQ, diff);
+
+        GST_LOG ("Transport stream bitrate: %" G_GUINT64_FORMAT, bitrate);
+
+        if (bitrate < mux->bitrate) {
+          GST_LOG_OBJECT (mux, "Padding transport stream");
+
+          if (!tsmux_get_buffer (mux, &buf)) {
+            ret = FALSE;
+            goto done;
+          }
+
+          gst_buffer_map (buf, &map, GST_MAP_READ);
+
+          tsmux_write_null_ts_header (map.data);
+
+          gst_buffer_unmap (buf, &map);
+
+          if (!(ret = tsmux_packet_out (mux, buf, -1)))
+            goto done;
+        }
+      } else {
+        break;
+      }
+    } else {
+      break;
+    }
+  } while (bitrate < mux->bitrate);
+
+done:
+  return ret;
+}
+
 /**
  * tsmux_write_stream_packet:
  * @mux: a #TsMux
@@ -1052,6 +1115,11 @@ tsmux_write_stream_packet (TsMux * mux, TsMuxStream * stream)
     else
       cur_ts = tsmux_stream_get_pts (stream);
 
+    if (mux->bitrate) {
+      if (!pad_stream (mux, stream, cur_ts))
+        goto fail;
+    }
+
     cur_pcr = 0;
     if (cur_ts != G_MININT64) {
       TS_DEBUG ("TS for PCR stream is %" G_GINT64_FORMAT, cur_ts);
@@ -1165,9 +1233,10 @@ tsmux_write_stream_packet (TsMux * mux, TsMuxStream * stream)
   /* ERRORS */
 fail:
   {
+    if (buf) {
       gst_buffer_unmap (buf, &map);
-    if (buf)
       gst_buffer_unref (buf);
+    }
     return FALSE;
   }
 }
@@ -1312,3 +1381,9 @@ tsmux_write_pmt (TsMux * mux, TsMuxProgram * program)
   return tsmux_section_write_packet (GINT_TO_POINTER (GST_MPEGTS_SECTION_PMT),
       &program->pmt, mux);
 }
+
+void
+tsmux_set_bitrate (TsMux * mux, guint64 bitrate)
+{
+  mux->bitrate = bitrate;
+}

gst/mpegtsmux/tsmux/tsmux.h

@@ -178,6 +178,9 @@ struct TsMux {
 
   /* scratch space for writing ES_info descriptors */
   guint8 es_info_buf[TSMUX_MAX_ES_INFO_LENGTH];
+
+  guint64 bitrate;
+  guint64 n_bytes;
 };
 
 /* create/free new muxer session */
@@ -191,6 +194,7 @@ void 		tsmux_set_pat_interval          (TsMux *mux, guint interval);
 guint 		tsmux_get_pat_interval          (TsMux *mux);
 void 		tsmux_resend_pat                (TsMux *mux);
 guint16		tsmux_get_new_pid 		(TsMux *mux);
+void    tsmux_set_bitrate       (TsMux *mux, guint64 bitrate);
 
 /* pid/program management */
 TsMuxProgram *	tsmux_program_new 		(TsMux *mux, gint prog_id);

gst/mpegtsmux/tsmux/tsmuxcommon.h

@@ -121,6 +121,8 @@ G_BEGIN_DECLS
 #define TSMUX_DEFAULT_PMT_INTERVAL (TSMUX_CLOCK_FREQ / 10)
 /* SI  interval (1/10th sec) */
 #define TSMUX_DEFAULT_SI_INTERVAL  (TSMUX_CLOCK_FREQ / 10)
+/* Bitrate (bits per second) */
+#define TSMUX_DEFAULT_BITRATE      0
 
 typedef struct TsMuxPacketInfo TsMuxPacketInfo;
 typedef struct TsMuxProgram TsMuxProgram;

gst/mpegtsmux/tsmux/tsmuxstream.c

@@ -224,6 +224,8 @@ tsmux_stream_new (guint16 pid, TsMuxStreamType stream_type)
       break;
   }
 
+  stream->first_ts = GST_CLOCK_STIME_NONE;
+
   stream->last_pts = GST_CLOCK_STIME_NONE;
   stream->last_dts = GST_CLOCK_STIME_NONE;
 

gst/mpegtsmux/tsmux/tsmuxstream.h

@@ -197,6 +197,8 @@ struct TsMuxStream {
   gint64 last_dts;
   gint64 last_pts;
 
+  gint64 first_ts;
+
   /* count of programs using this as PCR */
   gint   pcr_ref;
   /* Next time PCR should be written */