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mxfdemux: Handle temporal reordering shift

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This is similar to how the same issue was handled in qtdemux.

In order for the "DTS <= PTS" constraint to be respected, we calculate the
maximum temporal reordering that can happen (via index tables).

If there is a non-0 temporal reordering, we:
* Shift all outgoing PTS by that amount
* Shift segment for that stream by that amount
* Don't modify DTS (i.e. they might end up having negative running-time, before
the start of the segment)

Also ensure all entries have a valid PTS set, previously this wouldn't be set
for entries with a temporal offset of 0.

Fixes https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/issues/584

(and maybe a lot of other issues)

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/2371>
This commit is contained in:
Edward Hervey 2021-06-17 16:38:54 +02:00 committed by Edward Hervey
parent de19e8a84f
commit dfee771afd
2 changed files with 64 additions and 3 deletions
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63
gst/mxf/mxfdemux.c
View file

@ -1728,6 +1728,7 @@ gst_mxf_demux_handle_generic_container_essence_element (GstMXFDemux * demux,
gboolean keyframe = TRUE;
/* As in GstMXFDemuxIndex */
guint64 pts = G_MAXUINT64, dts = G_MAXUINT64;
gint32 max_temporal_offset = 0;
GST_DEBUG_OBJECT (demux,
"Handling generic container essence element of size %" G_GSIZE_FORMAT
@ -1858,6 +1859,19 @@ gst_mxf_demux_handle_generic_container_essence_element (GstMXFDemux * demux,
}
}
if (!index_table)
GST_DEBUG_OBJECT (demux,
"Couldn't find index table for body_sid:%d index_sid:%d",
etrack->body_sid, etrack->index_sid);
else {
GST_DEBUG_OBJECT (demux,
"Looking for position %" G_GINT64_FORMAT
" in index table of size %d (max temporal offset %u)",
etrack->position, index_table->offsets->len,
index_table->max_temporal_offset);
max_temporal_offset = index_table->max_temporal_offset;
}
if (index_table && index_table->offsets->len > etrack->position) {
GstMXFDemuxIndex *index =
&g_array_index (index_table->offsets, GstMXFDemuxIndex,
@ -1960,6 +1974,14 @@ gst_mxf_demux_handle_generic_container_essence_element (GstMXFDemux * demux,
gst_util_uint64_scale (pad->current_component_start_position *
GST_SECOND, pad->material_track->edit_rate.d,
pad->material_track->edit_rate.n);
/* We are dealing with reordered data, the PTS is shifted forward by the
* maximum temporal reordering (the DTS remain as-is). */
if (max_temporal_offset > 0)
GST_BUFFER_PTS (outbuf) +=
gst_util_uint64_scale (max_temporal_offset * GST_SECOND,
pad->current_essence_track->source_track->edit_rate.d,
pad->current_essence_track->source_track->edit_rate.n);
} else {
GST_BUFFER_PTS (outbuf) = GST_CLOCK_TIME_NONE;
}
@ -2017,7 +2039,26 @@ gst_mxf_demux_handle_generic_container_essence_element (GstMXFDemux * demux,
gst_pad_push_event (GST_PAD_CAST (pad),
gst_event_ref (demux->close_seg_event));
e = gst_event_new_segment (&demux->segment);
if (max_temporal_offset > 0) {
GstSegment shift_segment;
/* Handle maximum temporal offset. We are shifting all output PTS for
* this stream by the greatest temporal reordering that can occur. In
* order not to change the stream/running time we shift the segment
* start and stop values accordingly */
gst_segment_copy_into (&demux->segment, &shift_segment);
if (GST_CLOCK_TIME_IS_VALID (shift_segment.start))
shift_segment.start +=
gst_util_uint64_scale (max_temporal_offset * GST_SECOND,
pad->current_essence_track->source_track->edit_rate.d,
pad->current_essence_track->source_track->edit_rate.n);
if (GST_CLOCK_TIME_IS_VALID (shift_segment.stop))
shift_segment.stop +=
gst_util_uint64_scale (max_temporal_offset * GST_SECOND,
pad->current_essence_track->source_track->edit_rate.d,
pad->current_essence_track->source_track->edit_rate.n);
e = gst_event_new_segment (&shift_segment);
} else
e = gst_event_new_segment (&demux->segment);
gst_event_set_seqnum (e, demux->seqnum);
gst_pad_push_event (GST_PAD_CAST (pad), e);
pad->need_segment = FALSE;
@ -3756,6 +3797,7 @@ collect_index_table_segments (GstMXFDemux * demux)
t = g_new0 (GstMXFDemuxIndexTable, 1);
t->body_sid = segment->body_sid;
t->index_sid = segment->index_sid;
t->max_temporal_offset = 0;
t->offsets = g_array_new (FALSE, TRUE, sizeof (GstMXFDemuxIndex));
demux->index_tables = g_list_prepend (demux->index_tables, t);
}
@ -3808,8 +3850,19 @@ collect_index_table_segments (GstMXFDemux * demux)
gint8 temporal_offset = segment->index_entries[i].temporal_offset;
guint64 pts_i = G_MAXUINT64;
if (temporal_offset > 0 ||
(temporal_offset < 0 && start + i >= -(gint) temporal_offset)) {
/* Store the highest reordering offset (to ensure we never output
* buffer with DTS greater than PTS) */
if (temporal_offset > (gint) t->max_temporal_offset) {
GST_LOG_OBJECT (demux,
"bodySID:%d indexSID:%d Stored new max temporal offset %d (was %d)",
t->body_sid, t->index_sid, temporal_offset,
t->max_temporal_offset);
t->max_temporal_offset = temporal_offset;
}
/* Fetch the matching entry in presentation order to store the pts (in
* edit units). */
if (temporal_offset >= 0 || (start + i >= -(gint) temporal_offset)) {
pts_i = start + i + temporal_offset;
if (t->offsets->len < pts_i)
@ -3827,6 +3880,10 @@ collect_index_table_segments (GstMXFDemux * demux)
index->pts = start + i;
}
/* Fetch the matching entry in encoded/bitstream order to store all
* the other values related to the actual content (offset, flag, dts,
* ..) */
index = &g_array_index (t->offsets, GstMXFDemuxIndex, start + i);
if (!index->initialized) {
index->initialized = TRUE;

4
gst/mxf/mxfdemux.h
View file

@ -104,6 +104,10 @@ typedef struct
guint32 body_sid;
guint32 index_sid;
/* Greatest temporal offset value contained within offsets.
* Unsigned because the smallest value is 0 (no reordering) */
guint max_temporal_offset;
/* offsets indexed by DTS */
GArray *offsets;
} GstMXFDemuxIndexTable;