sön 2018-06-10 klockan 12:36 +0200 skrev Marton Balint:
> Also compute the correct essence_offset and essence_length for all clip
> wrapped
> essences.
>
> > Signed-off-by: Marton Balint <c...@passwd.hu>
> ---
> libavformat/mxfdec.c | 108
> +++++++++++++++++++++++++++------------------------
> 1 file changed, 57 insertions(+), 51 deletions(-)
>
> diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
> index 1ab34f4873..67b0028e88 100644
> --- a/libavformat/mxfdec.c
> +++ b/libavformat/mxfdec.c
> @@ -98,6 +98,7 @@ typedef struct MXFPartition {
> int pack_length;
> int64_t pack_ofs; ///< absolute offset of pack in file,
> including run-in
> int64_t body_offset;
> + KLVPacket first_essence_klv;
> } MXFPartition;
>
> typedef struct MXFCryptoContext {
> @@ -2782,47 +2783,76 @@ static int
> mxf_parse_handle_partition_or_eof(MXFContext *mxf)
> return mxf->parsing_backward ? mxf_seek_to_previous_partition(mxf) : 1;
> }
>
> +static int64_t round_to_kag(int64_t position, int kag_size)
> +{
> + /* TODO: account for run-in? the spec isn't clear whether KAG should
> account for it */
> + /* NOTE: kag_size may be any integer between 1 - 2^10 */
> + int64_t ret = (position / kag_size) * kag_size;
> + return ret == position ? ret : ret + kag_size;
This should probably just be
return ((position + kag_size - 1) / kag_size) * kag_size;
but maybe there's some fine point I'm overlooking. What happens if
kag_size is a smallish value like 16?
A check for position > INT64_MAX - kag_size might also be appropriate.
> +}
> +
> +static MXFWrappingScheme mxf_get_wrapping_by_body_sid(AVFormatContext *s,
> int body_sid)
> +{
> + for (int i = 0; i < s->nb_streams; i++) {
> + MXFTrack *track = s->streams[i]->priv_data;
> + if (track && track->body_sid == body_sid && track->wrapping !=
> UnknownWrapped)
> + return track->wrapping;
> + }
> + return UnknownWrapped;
> +}
> +
> /**
> * Figures out the proper offset and length of the essence container in each
> partition
> */
> -static void mxf_compute_essence_containers(MXFContext *mxf)
> +static void mxf_compute_essence_containers(AVFormatContext *s)
> {
> + MXFContext *mxf = s->priv_data;
> int x;
>
> - /* everything is already correct */
> - if (mxf->op == OPAtom)
> - return;
> -
> for (x = 0; x < mxf->partitions_count; x++) {
> MXFPartition *p = &mxf->partitions[x];
> + MXFWrappingScheme wrapping;
>
> if (!p->body_sid)
> continue; /* BodySID == 0 -> no essence */
>
> - if (x >= mxf->partitions_count - 1)
> - break; /* FooterPartition - can't compute length (and
> we don't need to) */
> + /* for non clip-wrapped essences we compute essence_offset
> + * for clip wrapped essences we point essence_offset after the KL
> (usually klv.offset + 20 or 25)
> + */
>
> - /* essence container spans to the next partition */
> - p->essence_length = mxf->partitions[x+1].this_partition -
> p->essence_offset;
> + wrapping = (mxf->op == OPAtom) ? ClipWrapped :
> mxf_get_wrapping_by_body_sid(s, p->body_sid);
>
> - if (p->essence_length < 0) {
> - /* next ThisPartition < essence_offset */
> - p->essence_length = 0;
> - av_log(mxf->fc, AV_LOG_ERROR,
> - "partition %i: bad ThisPartition = %"PRIX64"\n",
> - x+1, mxf->partitions[x+1].this_partition);
> + if (wrapping == ClipWrapped) {
> + p->essence_offset = p->first_essence_klv.next_klv -
> p->first_essence_klv.length;
> + p->essence_length = p->first_essence_klv.length;
Much nicer
> + } else {
> + int64_t op1a_essence_offset =
> + p->this_partition +
> + round_to_kag(p->pack_length, p->kag_size) +
> + round_to_kag(p->header_byte_count, p->kag_size) +
> + round_to_kag(p->index_byte_count, p->kag_size);
Is this really always the case? I guess with OP1a it isn't a huge
concern since the demuxer will find the next essence packet anyway. But
still..
I'm also fairly sure this is my code originally so.. :)
The rest looks OK
/Tomas
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