libavformat/mxfdec.c: support demuxing opatom audio without index

Reviewed-by: Tomas Härdin <tomas.hardin@codemill.se>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/mxfdec.c

@@ -2461,6 +2461,64 @@ static void mxf_handle_small_eubc(AVFormatContext *s)
     mxf->edit_units_per_packet = 1920;
 }
 
+/**
+ * Deal with the case where OPAtom files does not have any IndexTableSegments.
+ */
+static int mxf_handle_missing_index_segment(MXFContext *mxf)
+{
+    AVFormatContext *s = mxf->fc;
+    AVStream *st = NULL;
+    MXFIndexTableSegment *segment = NULL;
+    MXFPartition *p = NULL;
+    int essence_partition_count = 0;
+    int i, ret;
+
+    if (mxf->op != OPAtom)
+        return 0;
+
+    /* TODO: support raw video without a index if they exist */
+    if (s->nb_streams != 1 || s->streams[0]->codec->codec_type != AVMEDIA_TYPE_AUDIO || !is_pcm(s->streams[0]->codec->codec_id))
+        return 0;
+
+    /* check if file already has a IndexTableSegment */
+    for (i = 0; i < mxf->metadata_sets_count; i++) {
+        if (mxf->metadata_sets[i]->type == IndexTableSegment)
+            return 0;
+    }
+
+    /* find the essence partition */
+    for (i = 0; i < mxf->partitions_count; i++) {
+        /* BodySID == 0 -> no essence */
+        if (!mxf->partitions[i].body_sid)
+            continue;
+
+        p = &mxf->partitions[i];
+        essence_partition_count++;
+    }
+
+    /* only handle files with a single essence partition */
+    if (essence_partition_count != 1)
+        return 0;
+
+    if (!(segment = av_mallocz(sizeof(*segment))))
+        return AVERROR(ENOMEM);
+
+    if ((ret = mxf_add_metadata_set(mxf, segment))) {
+        mxf_free_metadataset((MXFMetadataSet**)&segment);
+        return ret;
+    }
+
+    st = s->streams[0];
+    segment->type = IndexTableSegment;
+    /* stream will be treated as small EditUnitByteCount */
+    segment->edit_unit_byte_count = (av_get_bits_per_sample(st->codec->codec_id) * st->codec->channels) >> 3;
+    segment->index_start_position = 0;
+    segment->index_duration = s->streams[0]->duration;
+    segment->index_sid = p->index_sid;
+    segment->body_sid = p->body_sid;
+    return 0;
+}
+
 static void mxf_read_random_index_pack(AVFormatContext *s)
 {
     MXFContext *mxf = s->priv_data;
@@ -2623,6 +2681,7 @@ static int mxf_read_header(AVFormatContext *s)
     if ((ret = mxf_parse_structural_metadata(mxf)) < 0)
         goto fail;
 
+    mxf_handle_missing_index_segment(mxf);
     if ((ret = mxf_compute_index_tables(mxf)) < 0)
         goto fail;