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qtdemux: Extract CEA608 framerate from the (first) video stream

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EA608 closed caption tracks are a bit special in that each sample
can contain CCs for multiple frames, and CCs can be omitted and have to
be inferred from the duration of the sample then.

As such we take the framerate from the (first) video track here for
CEA608 as there must be one CC byte pair for every video frame
according to the spec.

For CEA708 all is fine and there is one sample per frame.
This commit is contained in:
Sebastian Dröge 2018-12-20 11:31:58 +02:00 committed by Sebastian Dröge
parent ac8fc4419a
commit d471be4f3a
1 changed files with 44 additions and 10 deletions
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54
gst/isomp4/qtdemux.c
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@ -8518,19 +8518,53 @@ gst_qtdemux_configure_stream (GstQTDemux * qtdemux, QtDemuxStream * stream)
}
}
else if (stream->subtype == FOURCC_clcp) {
gboolean fps_available = gst_qtdemux_guess_framerate (qtdemux, stream);
else if (stream->subtype == FOURCC_clcp && CUR_STREAM (stream)->caps) {
const GstStructure *s;
QtDemuxStream *fps_stream = NULL;
gboolean fps_available = FALSE;
if (CUR_STREAM (stream)->caps) {
CUR_STREAM (stream)->caps =
gst_caps_make_writable (CUR_STREAM (stream)->caps);
/* CEA608 closed caption tracks are a bit special in that each sample
* can contain CCs for multiple frames, and CCs can be omitted and have to
* be inferred from the duration of the sample then.
*
* As such we take the framerate from the (first) video track here for
* CEA608 as there must be one CC byte pair for every video frame
* according to the spec.
*
* For CEA708 all is fine and there is one sample per frame.
*/
/* set framerate if calculated framerate is reliable */
if (fps_available) {
gst_caps_set_simple (CUR_STREAM (stream)->caps,
"framerate", GST_TYPE_FRACTION, CUR_STREAM (stream)->fps_n,
CUR_STREAM (stream)->fps_d, NULL);
s = gst_caps_get_structure (CUR_STREAM (stream)->caps, 0);
if (gst_structure_has_name (s, "closedcaption/x-cea-608")) {
gint i;
for (i = 0; i < QTDEMUX_N_STREAMS (qtdemux); i++) {
QtDemuxStream *tmp = QTDEMUX_NTH_STREAM (qtdemux, i);
if (tmp->subtype == FOURCC_vide) {
fps_stream = tmp;
break;
}
}
if (fps_stream) {
fps_available = gst_qtdemux_guess_framerate (qtdemux, fps_stream);
CUR_STREAM (stream)->fps_n = CUR_STREAM (fps_stream)->fps_n;
CUR_STREAM (stream)->fps_d = CUR_STREAM (fps_stream)->fps_d;
}
} else {
fps_available = gst_qtdemux_guess_framerate (qtdemux, stream);
fps_stream = stream;
}
CUR_STREAM (stream)->caps =
gst_caps_make_writable (CUR_STREAM (stream)->caps);
/* set framerate if calculated framerate is reliable */
if (fps_available) {
gst_caps_set_simple (CUR_STREAM (stream)->caps,
"framerate", GST_TYPE_FRACTION, CUR_STREAM (stream)->fps_n,
CUR_STREAM (stream)->fps_d, NULL);
}
}