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mxfdec: Add mxf_edit_unit_absolute_offset()

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This maps an EditUnit in an index table to the corresponding absolute offset
in the file.
This commit is contained in:
Tomas Härdin 2011-12-15 16:53:38 +01:00
parent b56adc7842
commit 36c305f9db
1 changed files with 49 additions and 0 deletions
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49
libavformat/mxfdec.c
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@ -1014,6 +1014,55 @@ 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;