On Fri, 5 Nov 2021, Marc-Antoine Arnaud wrote:
---
libavformat/mxf.h | 1 +
libavformat/mxfdec.c | 280 ++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 275 insertions(+), 6 deletions(-)
Could you mention in the commit description which
standards/recommendations cover MCA in mxf?
[...]
@@ -2328,7 +2480,9 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
AVStream *st;
FFStream *sti;
AVTimecode tc;
+ enum AVAudioServiceType *ast;
This declaration can be pushed down to where it is used.
[...]
+ // Soundfield group
+ if (IS_KLV_KEY(mca_sub_descriptor->mca_label_dictionary_id,
mxf_soundfield_group)) {
+ MXFSoundfieldGroupUL* group_ptr =
(MXFSoundfieldGroupUL*)&mxf_soundfield_groups[0];
const MXFSoundfieldGroupUL *group_ptr = mxf_soundfield_groups;
+
+ while (group_ptr->uid[0]) {
+ if (IS_KLV_KEY(group_ptr->uid,
mca_sub_descriptor->mca_label_dictionary_id)) {
+ st->codecpar->channel_layout = group_ptr->id;
+ break;
+ }
+ group_ptr++;
+ }
+ }
+
+ // Audio channel
+ if (IS_KLV_KEY(mca_sub_descriptor->mca_label_dictionary_id,
mxf_audio_channel)) {
+ MXFChannelOrderingUL* channel_ordering_ptr =
(MXFChannelOrderingUL*)&mxf_channel_ordering[0];
const MXFChannelOrderingUL *channel_ordering_ptr = mxf_channel_ordering;
+
+ while (channel_ordering_ptr->uid[0]) {
+ if (IS_KLV_KEY(channel_ordering_ptr->uid,
mca_sub_descriptor->mca_label_dictionary_id)) {
You should check if current_channel < desciptor->channels here, and if
not, then warn the user and break out of the loop. Otherwise
current_channel can grow out of array limits.
It should also be checked that channel_ordering_ptr->index <
descriptor->channels, and if not, then similarly, warn the user and break
out.
Maybe a hard failure (returning AVERROR_INVALIDDATA) is not necessary, to
allow some slightly invalid metadata?
+ source_track->channel_ordering[current_channel] =
channel_ordering_ptr->index;
+
+ if(channel_ordering_ptr->service_type !=
AV_AUDIO_SERVICE_TYPE_NB) {
+ uint8_t* side_data =
av_stream_new_side_data(st, AV_PKT_DATA_AUDIO_SERVICE_TYPE, sizeof(*ast));
+ if (!side_data)
+ goto fail_and_free;
+ ast = (enum AVAudioServiceType*)side_data;
+ *ast = channel_ordering_ptr->service_type;
+ }
+
+ current_channel += 1;
+ break;
+ }
+ channel_ordering_ptr++;
+ }
+ }
+
[...]
+ source_track->require_reordering = 0;
+ for (j = 0; j < descriptor->channels; ++j) {
+ if (source_track->channel_ordering[j] != j) {
+ source_track->require_reordering = 1;
+ break;
+ }
+ }
If require_reordering == 1 here but either codec is not PCM or
skip_audio_reordering is set then channel_layout should be reset to 0
(unknown). Maybe you should also set require_reordering to 0 in either of
these cases, so further along you no longer have to check codec and
skip_audio_reordering, only require_reordering.
+
+ if (source_track->require_reordering &&
is_pcm(st->codecpar->codec_id)) {
+ current_channel = 0;
+ av_log(mxf->fc, AV_LOG_DEBUG, "MCA Audio mapping (");
+ for(j = 0; j < descriptor->channels; ++j) {
+ for(int k = 0; k < descriptor->channels; ++k) {
+ if(source_track->channel_ordering[k] ==
current_channel) {
+ av_log(mxf->fc, AV_LOG_DEBUG, "%d -> %d",
source_track->channel_ordering[k], k);
+ if (current_channel != descriptor->channels - 1)
+ av_log(mxf->fc, AV_LOG_DEBUG, ", ");
+ current_channel += 1;
+ }
+ }
+ }
+ av_log(mxf->fc, AV_LOG_DEBUG, ")\n");
+ }
[...]
@@ -3920,6 +4185,9 @@ static const AVOption options[] = {
{ "eia608_extract", "extract eia 608 captions from s436m track",
offsetof(MXFContext, eia608_extract), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1,
AV_OPT_FLAG_DECODING_PARAM },
+ { "skip_audio_reordering", "skip audio reordering based on Multi-Channel Audio
labelling",
+ offsetof(MXFContext, skip_audio_reordering), AV_OPT_TYPE_BOOL, {.i64 =
0}, 0, 1,
+ AV_OPT_FLAG_DECODING_PARAM },
Docs update (doc/demuxers.texi) and libavformat version micro bump is
missing for the new option.
Thanks,
Marton
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