tsdemux: Wait for valid PCR/offset obvervations

It is quite possible that we might get PTS/DTS before the first PCR/Offset observation. In order to end up with valid timestamp we wait until at least one stream was able to get a proper running-time for any PTS/DTS. Until then, we queue up the pending buffers to push out. Once we see a first valid timestamp, we re-evaluate the amount of running-time elapsed (based on returned inital running-time and amount of data/DTS queued up) for any given stream. Taking the biggest amount of elapsed time, we set that on the packetizer as the initial offset and recalculate all pending buffers running-time PTS/DTS. Note: The buffer queueing system can also be used later on for the dvb fast start proposal (where we queue up all stream packets before seeing PAT/PMT and then push them once we know if they belong to the chosen program).
2024-07-03 21:25:54 +00:00 · 2013-07-29 08:10:07 +02:00 · 2013-07-29 08:10:07 +02:00 · 0e9ce593bf
parent a4ee1abb15
commit 0e9ce593bf
1 changed files with 210 additions and 22 deletions
--- a/gst/mpegtsdemux/tsdemux.c
+++ b/gst/mpegtsdemux/tsdemux.c
@ -97,6 +97,16 @@ typedef enum
                                 * Drop all incoming buffers */
 } PendingPacketState;

+/* Pending buffer */
+typedef struct
+{
+  /* The fully reconstructed buffer */
+  GstBuffer *buffer;
+
+  /* Raw PTS/DTS (in 90kHz units) */
+  guint64 pts, dts;
+} PendingBuffer;
+
 typedef struct _TSDemuxStream TSDemuxStream;

 struct _TSDemuxStream
@ -104,35 +114,49 @@ struct _TSDemuxStream
  MpegTSBaseStream stream;

  GstPad *pad;
+
  /* Whether the pad was added or not */
  gboolean active;

+  /* TRUE if we are waiting for a valid timestamp */
+  gboolean pending_ts;
+
  /* the return of the latest push */
  GstFlowReturn flow_return;

  /* Output data */
  PendingPacketState state;

-  /* Data to push (allocated) */
+  /* Data being reconstructed (allocated) */
  guint8 *data;

-  /* Size of data to push (if known) */
+  /* Size of data being reconstructed (if known, else 0) */
  guint expected_size;

-  /* Size of currently queued data */
+  /* Amount of bytes in current ->data */
  guint current_size;
+  /* Size of ->data */
  guint allocated_size;

-  /* Current PTS/DTS for this stream */
+  /* Current PTS/DTS for this stream (in running time) */
  GstClockTime pts;
  GstClockTime dts;

+  /* Current PTS/DTS for this stream (in 90kHz unit) */
+  guint64 raw_pts, raw_dts;
+
  /* Whether this stream needs to send a newsegment */
  gboolean need_newsegment;

+  /* The value to use when calculating the newsegment */
+  GstClockTime first_dts;
+
  GstTagList *taglist;

  gint continuity_counter;
+
+  /* List of pending buffers */
+  GList *pending;
 };

 #define VIDEO_CAPS \
@ -1059,6 +1083,10 @@ gst_ts_demux_stream_added (MpegTSBase * base, MpegTSBaseStream * bstream,
    stream->need_newsegment = TRUE;
    stream->pts = GST_CLOCK_TIME_NONE;
    stream->dts = GST_CLOCK_TIME_NONE;
+    stream->raw_pts = -1;
+    stream->raw_dts = -1;
+    stream->pending_ts = TRUE;
+    stream->first_dts = GST_CLOCK_TIME_NONE;
    stream->continuity_counter = CONTINUITY_UNSET;
  }
  stream->flow_return = GST_FLOW_OK;
@ -1121,8 +1149,6 @@ activate_pad_for_stream (GstTSDemux * tsdemux, TSDemuxStream * stream)
 static void
 gst_ts_demux_stream_flush (TSDemuxStream * stream)
 {
-  stream->pts = GST_CLOCK_TIME_NONE;
-
  GST_DEBUG ("flushing stream %p", stream);

  if (stream->data)
@ -1135,6 +1161,9 @@ gst_ts_demux_stream_flush (TSDemuxStream * stream)
  stream->need_newsegment = TRUE;
  stream->pts = GST_CLOCK_TIME_NONE;
  stream->dts = GST_CLOCK_TIME_NONE;
+  stream->first_dts = GST_CLOCK_TIME_NONE;
+  stream->raw_pts = -1;
+  stream->raw_dts = -1;
  if (stream->flow_return == GST_FLOW_FLUSHING) {
    stream->flow_return = GST_FLOW_OK;
  }
@ -1190,6 +1219,7 @@ gst_ts_demux_record_pts (GstTSDemux * demux, TSDemuxStream * stream,
 {
  MpegTSBaseStream *bs = (MpegTSBaseStream *) stream;

+  stream->raw_pts = pts;
  if (pts == -1) {
    stream->pts = GST_CLOCK_TIME_NONE;
    return;
@ -1223,6 +1253,7 @@ gst_ts_demux_record_dts (GstTSDemux * demux, TSDemuxStream * stream,
 {
  MpegTSBaseStream *bs = (MpegTSBaseStream *) stream;

+  stream->raw_dts = dts;
  if (dts == -1) {
    stream->dts = GST_CLOCK_TIME_NONE;
    return;
@ -1250,6 +1281,131 @@ gst_ts_demux_record_dts (GstTSDemux * demux, TSDemuxStream * stream,
  }
 }

+/* This is called when we haven't got a valid initial PTS/DTS on all streams */
+static gboolean
+check_pending_buffers (GstTSDemux * demux, TSDemuxStream * stream)
+{
+  gboolean have_observation = FALSE;
+  /* The biggest offset */
+  guint64 offset = 0;
+  GList *tmp;
+
+  /* 1. Go over all streams */
+  for (tmp = demux->program->stream_list; tmp; tmp = tmp->next) {
+    TSDemuxStream *tmpstream = (TSDemuxStream *) tmp->data;
+    /* 1.1 check if at least one stream got a valid DTS */
+    if ((tmpstream->raw_dts != -1 && tmpstream->dts != GST_CLOCK_TIME_NONE) ||
+        (tmpstream->raw_pts != -1 && tmpstream->pts != GST_CLOCK_TIME_NONE)) {
+      have_observation = TRUE;
+      break;
+    }
+  }
+
+  /* 2. If we don't have a valid value yet, break out */
+  if (have_observation == FALSE)
+    return FALSE;
+
+  /* 3. Go over all streams that have current/pending data */
+  for (tmp = demux->program->stream_list; tmp; tmp = tmp->next) {
+    TSDemuxStream *tmpstream = (TSDemuxStream *) tmp->data;
+    PendingBuffer *pend;
+    guint64 firstval, lastval, ts;
+
+    /* 3.1 Calculate the offset between current DTS and first DTS */
+    if (tmpstream->pending == NULL || tmpstream->state == PENDING_PACKET_EMPTY)
+      continue;
+    /* If we don't have any pending data, the offset is 0 for this stream */
+    if (tmpstream->pending == NULL)
+      break;
+    if (tmpstream->raw_dts != -1)
+      lastval = tmpstream->raw_dts;
+    else if (tmpstream->raw_pts != -1)
+      lastval = tmpstream->raw_pts;
+    else {
+      GST_WARNING ("Don't have a last DTS/PTS to use for offset recalculation");
+      continue;
+    }
+    pend = tmpstream->pending->data;
+    if (pend->dts != -1)
+      firstval = pend->dts;
+    else if (pend->pts != -1)
+      firstval = pend->pts;
+    else {
+      GST_WARNING
+          ("Don't have a first DTS/PTS to use for offset recalculation");
+      continue;
+    }
+    /* 3.2 Add to the offset the report TS for the current DTS */
+    ts = mpegts_packetizer_pts_to_ts (MPEG_TS_BASE_PACKETIZER (demux),
+        MPEGTIME_TO_GSTTIME (lastval), demux->program->pcr_pid);
+    if (ts == GST_CLOCK_TIME_NONE) {
+      GST_WARNING ("THIS SHOULD NOT HAPPEN !");
+      continue;
+    }
+    ts += MPEGTIME_TO_GSTTIME (lastval - firstval);
+    /* 3.3 If that offset is bigger than the current offset, store it */
+    if (ts > offset)
+      offset = ts;
+  }
+
+  GST_DEBUG ("New initial pcr_offset %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (offset));
+
+  /* 4. Set the offset on the packetizer */
+  mpegts_packetizer_set_current_pcr_offset (MPEG_TS_BASE_PACKETIZER (demux),
+      offset, demux->program->pcr_pid);
+
+  /* 4. Go over all streams */
+  for (tmp = demux->program->stream_list; tmp; tmp = tmp->next) {
+    TSDemuxStream *stream = (TSDemuxStream *) tmp->data;
+
+    stream->pending_ts = FALSE;
+    /* 4.1 Set pending_ts for FALSE */
+
+    /* 4.2 Recalculate PTS/DTS (in running time) for pending data */
+    if (stream->pending) {
+      GList *tmp2;
+      for (tmp2 = stream->pending; tmp2; tmp2 = tmp2->next) {
+        PendingBuffer *pend = (PendingBuffer *) tmp2->data;
+        if (pend->pts != -1)
+          GST_BUFFER_PTS (pend->buffer) =
+              mpegts_packetizer_pts_to_ts (MPEG_TS_BASE_PACKETIZER (demux),
+              MPEGTIME_TO_GSTTIME (pend->pts), demux->program->pcr_pid);
+        if (pend->dts != -1)
+          GST_BUFFER_DTS (pend->buffer) =
+              mpegts_packetizer_pts_to_ts (MPEG_TS_BASE_PACKETIZER (demux),
+              MPEGTIME_TO_GSTTIME (pend->dts), demux->program->pcr_pid);
+        /* 4.2.2 Set first_dts to TS of lowest DTS (for segment) */
+        if (stream->first_dts == GST_CLOCK_TIME_NONE) {
+          if (GST_BUFFER_DTS (pend->buffer) != GST_CLOCK_TIME_NONE)
+            stream->first_dts = GST_BUFFER_DTS (pend->buffer);
+          else if (GST_BUFFER_PTS (pend->buffer) != GST_CLOCK_TIME_NONE)
+            stream->first_dts = GST_BUFFER_PTS (pend->buffer);
+        }
+      }
+    }
+    /* Recalculate PTS/DTS (in running time) for current data */
+    if (stream->state != PENDING_PACKET_EMPTY) {
+      if (stream->raw_dts != -1) {
+        stream->dts =
+            mpegts_packetizer_pts_to_ts (MPEG_TS_BASE_PACKETIZER (demux),
+            MPEGTIME_TO_GSTTIME (stream->raw_dts), demux->program->pcr_pid);
+        if (stream->first_dts == GST_CLOCK_TIME_NONE)
+          stream->first_dts = stream->dts;
+      }
+      if (stream->raw_pts != -1) {
+        stream->pts =
+            mpegts_packetizer_pts_to_ts (MPEG_TS_BASE_PACKETIZER (demux),
+            MPEGTIME_TO_GSTTIME (stream->raw_pts), demux->program->pcr_pid);
+        if (stream->first_dts == GST_CLOCK_TIME_NONE)
+          stream->first_dts = stream->pts;
+      }
+    }
+  }
+
+  return TRUE;
+}
+
 static void
 gst_ts_demux_parse_pes_header (GstTSDemux * demux, TSDemuxStream * stream,
    guint8 * data, guint32 length, guint64 bufferoffset)
@ -1270,6 +1426,17 @@ gst_ts_demux_parse_pes_header (GstTSDemux * demux, TSDemuxStream * stream,

  gst_ts_demux_record_dts (demux, stream, header.DTS, bufferoffset);
  gst_ts_demux_record_pts (demux, stream, header.PTS, bufferoffset);
+  if (G_UNLIKELY (stream->pending_ts &&
+          (stream->pts != GST_CLOCK_TIME_NONE
+              || stream->dts != GST_CLOCK_TIME_NONE))) {
+    GST_DEBUG ("Got pts/dts update, rechecking all streams");
+    check_pending_buffers (demux, stream);
+  } else if (stream->first_dts == GST_CLOCK_TIME_NONE) {
+    if (GST_CLOCK_TIME_IS_VALID (stream->dts))
+      stream->first_dts = stream->dts;
+    else if (GST_CLOCK_TIME_IS_VALID (stream->pts))
+      stream->first_dts = stream->pts;
+  }

  GST_DEBUG_OBJECT (demux,
      "stream PTS %" GST_TIME_FORMAT " DTS %" GST_TIME_FORMAT,
@ -1413,13 +1580,10 @@ calculate_and_push_newsegment (GstTSDemux * demux, TSDemuxStream * stream)
  for (tmp = demux->program->stream_list; tmp; tmp = tmp->next) {
    TSDemuxStream *pstream = (TSDemuxStream *) tmp->data;

-    if (GST_CLOCK_TIME_IS_VALID (pstream->pts)) {
-      if (!GST_CLOCK_TIME_IS_VALID (lowest_pts) || pstream->pts < lowest_pts)
-        lowest_pts = pstream->pts;
-    }
-    if (GST_CLOCK_TIME_IS_VALID (pstream->dts)) {
-      if (!GST_CLOCK_TIME_IS_VALID (lowest_pts) || pstream->dts < lowest_pts)
-        lowest_pts = pstream->dts;
+    if (GST_CLOCK_TIME_IS_VALID (pstream->first_dts)) {
+      if (!GST_CLOCK_TIME_IS_VALID (lowest_pts)
+          || pstream->first_dts < lowest_pts)
+        lowest_pts = pstream->first_dts;
    }
  }
  if (GST_CLOCK_TIME_IS_VALID (lowest_pts))
@ -1515,24 +1679,48 @@ gst_ts_demux_push_pending_data (GstTSDemux * demux, TSDemuxStream * stream)
    goto beach;
  }

-  if (G_UNLIKELY (!stream->active))
-    activate_pad_for_stream (demux, stream);
-
-  if (G_UNLIKELY (stream->pad == NULL)) {
-    g_free (stream->data);
-    goto beach;
-  }
-
  if (G_UNLIKELY (demux->program == NULL)) {
    GST_LOG_OBJECT (demux, "No program");
    g_free (stream->data);
    goto beach;
  }

+  buffer = gst_buffer_new_wrapped (stream->data, stream->current_size);
+
+  if (G_UNLIKELY (stream->pending_ts && !check_pending_buffers (demux, stream))) {
+    PendingBuffer *pend;
+    pend = g_slice_new0 (PendingBuffer);
+    pend->buffer = buffer;
+    pend->pts = stream->raw_pts;
+    pend->dts = stream->raw_dts;
+    stream->pending = g_list_append (stream->pending, pend);
+    GST_DEBUG ("Not enough information to push buffers yet, storing buffer");
+    goto beach;
+  }
+
+  if (G_UNLIKELY (!stream->active))
+    activate_pad_for_stream (demux, stream);
+
  if (G_UNLIKELY (stream->need_newsegment))
    calculate_and_push_newsegment (demux, stream);

-  buffer = gst_buffer_new_wrapped (stream->data, stream->current_size);
+  /* FIXME : Push pending buffers if any */
+  if (G_UNLIKELY (stream->pending)) {
+    GList *tmp;
+    for (tmp = stream->pending; tmp; tmp = tmp->next) {
+      PendingBuffer *pend = (PendingBuffer *) tmp->data;
+
+      GST_DEBUG_OBJECT (stream->pad,
+          "Pushing pending buffer PTS:%" GST_TIME_FORMAT " DTS:%"
+          GST_TIME_FORMAT, GST_TIME_ARGS (GST_BUFFER_PTS (pend->buffer)),
+          GST_TIME_ARGS (GST_BUFFER_DTS (pend->buffer)));
+
+      res = gst_pad_push (stream->pad, pend->buffer);
+      g_slice_free (PendingBuffer, pend);
+    }
+    g_list_free (stream->pending);
+    stream->pending = NULL;
+  }

  GST_DEBUG_OBJECT (stream->pad, "stream->pts %" GST_TIME_FORMAT,
      GST_TIME_ARGS (stream->pts));