From: Tomas Härdin <[email protected]>
This maps an EditUnit in an index table to the corresponding absolute offset
in the file.
---
libavformat/mxfdec.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 49 insertions(+), 0 deletions(-)
diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index d602818..b35f02d 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -1039,6 +1039,55 @@ static int64_t mxf_essence_container_length(MXFContext
*mxf, int body_sid)
return ret;
}
+/* EditUnit -> absolute offset */
+static int mxf_edit_unit_absolute_offset(MXFContext *mxf, MXFIndexTable
*index_table, int64_t edit_unit, int64_t *edit_unit_out, int64_t *offset_out,
int nag)
+{
+ int i;
+ int offset_temp = 0;
+
+ for (i = 0; i < index_table->nb_segments; i++) {
+ MXFIndexTableSegment *s = index_table->segments[i];
+
+ edit_unit = FFMAX(edit_unit, s->index_start_position); /* clamp if
trying to seek before start */
+
+ if (edit_unit < s->index_start_position + s->index_duration) {
+ int64_t index = edit_unit - s->index_start_position;
+
+ if (s->edit_unit_byte_count)
+ offset_temp += s->edit_unit_byte_count * index;
+ else if (s->nb_index_entries) {
+ if (s->nb_index_entries == 2 * s->index_duration + 1)
+ index *= 2; /* Avid index */
+
+ if (index < 0 || index > s->nb_index_entries) {
+ av_log(mxf->fc, AV_LOG_ERROR, "IndexSID %i segment at
%"PRId64" IndexEntryArray too small\n",
+ index_table->index_sid, s->index_start_position);
+ return AVERROR_INVALIDDATA;
+ }
+
+ offset_temp = s->stream_offset_entries[index];
+ } else {
+ av_log(mxf->fc, AV_LOG_ERROR, "IndexSID %i segment at
%"PRId64" missing EditUnitByteCount and IndexEntryArray\n",
+ index_table->index_sid, s->index_start_position);
+ return AVERROR_INVALIDDATA;
+ }
+
+ if (edit_unit_out)
+ *edit_unit_out = edit_unit;
+
+ return mxf_absolute_bodysid_offset(mxf, index_table->body_sid,
offset_temp, offset_out);
+ } else {
+ /* EditUnitByteCount == 0 for VBR indexes, which is fine since
they use explicit StreamOffsets */
+ offset_temp += s->edit_unit_byte_count * s->index_duration;
+ }
+ }
+
+ if (nag)
+ av_log(mxf->fc, AV_LOG_ERROR, "failed to map EditUnit %"PRId64" in
IndexSID %i to an offset\n", edit_unit, index_table->index_sid);
+
+ return AVERROR_INVALIDDATA;
+}
+
static int mxf_parse_index(MXFContext *mxf, int track_id, AVStream *st,
MXFIndexTableSegment **sorted_segments, int nb_sorted_segments)
{
int64_t accumulated_offset = 0;
--
1.7.8
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