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ccutils: Keep upstream padding payload

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A payload of 0x80 0x80 means that it's padding. It's not a good idea to
throw this away though, because of the cc_valid field.

According to CEA 10-B section 25.2.1, if cc_valid is zero, the run-in
clock and start bit should not be generated. In practice, this means
that any closed captions will be erased and the end-user TV will show
that captions are not available for this stream. This might have
undesired consequences, e.g. we were just showing a long line of
captions and we disable it before the user has had time to read it, or
you can't enable closed captions during silence/music intervals.

We cannot reliably detect whether there's a currently-silent closed
caption stream or just nothing, but we have this information coming from
upstream, so we can at least not discard it.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5508>
This commit is contained in:
Vivia Nikolaidou 2023-10-18 15:12:38 +03:00 committed by GStreamer Marge Bot
parent ca18e48882
commit 78bc3d53dd
2 changed files with 12 additions and 16 deletions
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12
subprojects/gst-plugins-bad/ext/closedcaption/ccutils.c
View file

@ -382,10 +382,8 @@ cc_data_extract_cea608 (const guint8 * cc_data, guint cc_data_len,
return CC_DATA_EXTRACT_TOO_MANY_FIELD1;
}
if (byte1 != 0x80 || byte2 != 0x80) {
cea608_field1[(*cea608_field1_len)++] = byte1;
cea608_field1[(*cea608_field1_len)++] = byte2;
}
cea608_field1[(*cea608_field1_len)++] = byte1;
cea608_field1[(*cea608_field1_len)++] = byte2;
}
} else if (cc_type == 0x01) {
if (!cc_valid)
@ -397,10 +395,8 @@ cc_data_extract_cea608 (const guint8 * cc_data, guint cc_data_len,
*cea608_field2_len + 2);
return CC_DATA_EXTRACT_TOO_MANY_FIELD2;
}
if (byte1 != 0x80 || byte2 != 0x80) {
cea608_field2[(*cea608_field2_len)++] = byte1;
cea608_field2[(*cea608_field2_len)++] = byte2;
}
cea608_field2[(*cea608_field2_len)++] = byte1;
cea608_field2[(*cea608_field2_len)++] = byte2;
}
} else {
/* all cea608 packets must be at the beginning of a cc_data */

16
subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c
View file

@ -458,10 +458,10 @@ GST_START_TEST (convert_cea708_cc_data_cea708_cdp)
{
const guint8 in[] = { 0xfc, 0x80, 0x80, 0xfe, 0x80, 0x80 };
const guint8 out[] =
{ 0x96, 0x69, 0x2b, 0x8f, 0x43, 0x00, 0x00, 0x72, 0xea, 0xf8, 0x00, 0x00,
{ 0x96, 0x69, 0x2b, 0x8f, 0x43, 0x00, 0x00, 0x72, 0xea, 0xfc, 0x80, 0x80,
0xfe, 0x80, 0x80, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
0xfa, 0x00, 0x00, 0x74, 0x00, 0x00, 0x6e
0xfa, 0x00, 0x00, 0x74, 0x00, 0x00, 0x6a
};
check_conversion (in, sizeof (in), out, sizeof (out),
"closedcaption/x-cea-708,format=(string)cc_data,framerate=(fraction)60/1",
@ -512,7 +512,7 @@ GST_START_TEST (convert_cea708_cdp_cea708_cc_data)
{ 0x96, 0x69, 0x13, 0x5f, 0x43, 0x00, 0x00, 0x72, 0xe2, 0xfc, 0x80, 0x80,
0xfd, 0x80, 0x80, 0x74, 0x00, 0x00, 0x8a
};
const guint8 out[] = { 0xf8, 0x00, 0x00, 0xf9, 0x00, 0x00 };
const guint8 out[] = { 0xfc, 0x80, 0x80, 0xfd, 0x80, 0x80 };
check_conversion_tc_passthrough (in, sizeof (in), out, sizeof (out),
"closedcaption/x-cea-708,format=(string)cdp,framerate=30/1",
"closedcaption/x-cea-708,format=(string)cc_data");
@ -813,21 +813,21 @@ GST_START_TEST (convert_cea708_cdp_cea708_cdp_from_drop_frame_scaling)
const guint8 out1[] =
{ 0x96, 0x69, 0x4e, 0x5f, 0xc3, 0x00, 0x00, 0x71, 0xc0, 0x81, 0x59, 0x29,
0x72, 0xf4, 0xf8, 0x00, 0x00, 0xf9, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x72, 0xf4, 0xfc, 0x80, 0x80, 0xf9, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0x74, 0x00, 0x00, 0xfe
0x00, 0x00, 0x74, 0x00, 0x00, 0xfa
};
const guint8 out2[] =
{ 0x96, 0x69, 0x4e, 0x5f, 0xc3, 0x00, 0x01, 0x71, 0xc0, 0x82, 0x00, 0x00,
0x72, 0xf4, 0xf8, 0x00, 0x00, 0xf9, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x72, 0xf4, 0xfc, 0x80, 0x80, 0xf9, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa,
0x00, 0x00, 0x74, 0x00, 0x01, 0x7d
0x00, 0x00, 0x74, 0x00, 0x01, 0x79
};
const guint8 *out[] = { out1, out2 };
guint out_len[] = { sizeof (out1), sizeof (out2) };
@ -1102,7 +1102,7 @@ GST_START_TEST (convert_cea708_cdp_cea708_cc_data_double_input_data)
* buffer */
const guint8 out1[] = { 0xfc, 0x81, 0x82, };
const guint8 out2[] = { 0xfd, 0x83, 0x84, };
const guint8 out3[] = { 0xfc, 0x85, 0x86, };
const guint8 out3[] = { 0xfc, 0x80, 0x80, };
const guint8 *out[] = { out1, out2, out3, };
guint out_len[] = { sizeof (out1), sizeof (out2), sizeof (out3), };
check_conversion_multiple (G_N_ELEMENTS (in_len), in, in_len,