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mxfdec: Compute packet offsets properly 

This replaces the old essence_offset code
This commit is contained in:
Tomas Härdin 2011-12-08 12:23:36 +01:00
parent 5fb800f49a
commit 5e67e3eac2
1 changed files with 38 additions and 23 deletions
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61
libavformat/mxfdec.c
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@ -190,9 +190,6 @@ typedef struct {
uint8_t *local_tags;
int local_tags_count;
uint64_t footer_partition;
int64_t essence_offset;
int first_essence_kl_length;
int64_t first_essence_length;
KLVPacket current_klv_data;
int current_klv_index;
int run_in;
@ -985,9 +982,36 @@ static int mxf_get_sorted_table_segments(MXFContext *mxf, int *nb_sorted_segment
return 0;
}
/**
* Computes the absolute file offset of the given essence container offset
*/
static int mxf_absolute_bodysid_offset(MXFContext *mxf, int body_sid, int64_t offset, int64_t *offset_out)
{
int x;
int64_t offset_in = offset; /* for logging */
for (x = 0; x < mxf->partitions_count; x++) {
MXFPartition *p = &mxf->partitions[x];
if (p->body_sid != body_sid)
continue;
if (offset < p->essence_length || !p->essence_length) {
*offset_out = p->essence_offset + offset;
return 0;
}
offset -= p->essence_length;
}
av_log(mxf->fc, AV_LOG_ERROR, "failed to find absolute offset of %lx in BodySID %i - partial file?\n",
offset_in, body_sid);
return AVERROR_INVALIDDATA;
}
static int mxf_parse_index(MXFContext *mxf, int track_id, AVStream *st)
{
int64_t accumulated_offset = 0;
int j, k, ret, nb_sorted_segments;
MXFIndexTableSegment **sorted_segments;
int n_delta = track_id - 1; /* TrackID = 1-based stream index */
@ -1005,10 +1029,6 @@ static int mxf_parse_index(MXFContext *mxf, int track_id, AVStream *st)
int64_t segment_size;
MXFIndexTableSegment *tableseg = sorted_segments[j];
/* reset accumulated_offset on BodySID change */
if (j > 0 && tableseg->body_sid != sorted_segments[j-1]->body_sid)
accumulated_offset = 0;
if (n_delta >= tableseg->nb_delta_entries && st->index != 0)
continue;
duration = tableseg->index_duration > 0 ? tableseg->index_duration :
@ -1054,7 +1074,7 @@ static int mxf_parse_index(MXFContext *mxf, int track_id, AVStream *st)
size = 0;
flags = !(tableseg->flag_entries[k] & 0x30) ? AVINDEX_KEYFRAME : 0;
} else {
pos = (int64_t)k * tableseg->edit_unit_byte_count + accumulated_offset;
pos = (int64_t)(tableseg->index_start_position + k) * tableseg->edit_unit_byte_count;
if (n_delta < tableseg->nb_delta_entries - 1)
size = tableseg->element_delta[n_delta+1] - tableseg->element_delta[n_delta];
else {
@ -1071,10 +1091,10 @@ static int mxf_parse_index(MXFContext *mxf, int track_id, AVStream *st)
flags = AVINDEX_KEYFRAME;
}
if (k > 0 && pos < mxf->first_essence_length && accumulated_offset == 0)
pos += mxf->first_essence_kl_length;
pos += mxf->essence_offset;
if (mxf_absolute_bodysid_offset(mxf, tableseg->body_sid, pos, &pos) < 0) {
/* probably partial file - no point going further for this stream */
break;
}
av_dlog(mxf->fc, "Stream %d IndexEntry %d TrackID %d Offset %"PRIx64" Timestamp %"PRId64"\n",
st->index, st->nb_index_entries, track_id, pos, sample_duration * st->nb_index_entries);
@ -1082,7 +1102,6 @@ static int mxf_parse_index(MXFContext *mxf, int track_id, AVStream *st)
if ((ret = av_add_index_entry(st, pos, sample_duration * st->nb_index_entries, size, 0, flags)) < 0)
return ret;
}
accumulated_offset += segment_size;
}
av_free(sorted_segments);
@ -1474,6 +1493,7 @@ static int mxf_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
MXFContext *mxf = s->priv_data;
KLVPacket klv;
int64_t essence_offset = 0;
mxf->last_forward_tell = INT64_MAX;
@ -1525,13 +1545,8 @@ static int mxf_read_header(AVFormatContext *s, AVFormatParameters *ap)
}
}
if (!mxf->essence_offset)
mxf->essence_offset = klv.offset;
if (!mxf->first_essence_kl_length && IS_KLV_KEY(klv.key, mxf_essence_element_key)) {
mxf->first_essence_kl_length = avio_tell(s->pb) - klv.offset;
mxf->first_essence_length = klv.length;
}
if (!essence_offset)
essence_offset = klv.offset;
/* seek to footer, previous partition or stop */
if (mxf_parse_handle_essence(mxf) <= 0)
@ -1565,11 +1580,11 @@ static int mxf_read_header(AVFormatContext *s, AVFormatParameters *ap)
avio_skip(s->pb, klv.length);
}
/* FIXME avoid seek */
if (!mxf->essence_offset) {
if (!essence_offset) {
av_log(s, AV_LOG_ERROR, "no essence\n");
return AVERROR_INVALIDDATA;
}
avio_seek(s->pb, mxf->essence_offset, SEEK_SET);
avio_seek(s->pb, essence_offset, SEEK_SET);
mxf_compute_essence_containers(mxf);