Mon Dec 20, 2021 9:15 pm
Hi Matt,
I have downloaded your provided samples and I can extract the Closed Captions from all of them.
There are 3 different ways the 608/708 data are embedded in those samples.
In the files named 720ts_6DK01H_tru720og.ts and 1080i_PS_SampleFileCC.mpg, the 608/708 data are in the MPEG-2 Picture Extension User Data according to ATSC A/53 Part 4 Section 6.2. Using mediainfo you will see something like this:
Text #1
ID : 224 (0xE0)-CC1
Format : EIA-608
Muxing mode : A/53 / DTVCC Transport
Muxing mode, more info : Muxed in Video #1
Duration : 4 min 14 s
Bit rate mode : Constant
Stream size : 0.00 Byte (0%)
CaptionServiceName : CC1
Text #2
ID : 224 (0xE0)-1
Format : EIA-708
Muxing mode : A/53 / DTVCC Transport
Muxing mode, more info : Muxed in Video #1
Duration : 4 min 14 s
Bit rate mode : Constant
Stream size : 0.00 Byte (0%)
The file 1080i_PS_SampleFileCC.mpg contains the 608/708 data as MPEG-4 NAL units of type SEI according to SCTE 128-1 section 8.1 and 8.2, so mediainfo will show something like this:
Text #1
ID : 1-CC1
Format : EIA-608
Muxing mode : SCTE 128 / DTVCC Transport
Muxing mode, more info : Muxed in Video #1
Duration : 2 min 46 s
Bit rate mode : Constant
Stream size : 0.00 Byte (0%)
CaptionServiceName : CC1
Text #2
ID : 1-1
Format : EIA-708
Muxing mode : SCTE 128 / DTVCC Transport
Muxing mode, more info : Muxed in Video #1
Duration : 2 min 46 s
Bit rate mode : Constant
Stream size : 0.00 Byte (0%)
Finally, the MXF file 1080mxf_708_I28706.mxf uses a separate SMPTE 436M track which contains the CDP (Caption Distribution Packets) as VANC data - so this is the only case where the CC are not embedded into video and this is the closest to what I have been using with OP-47.
The mediainfo output for the MXF is like this:
Text
ID : 1280-1
Format : EIA-708
Muxing mode : Ancillary data / CDP
Duration : 3 min 6 s
Bit rate mode : Constant
Stream size : 0.00 Byte (0%)
Language : English
So with a bit of effort all these files can be output using a Decklink card to SDI with the 608/708 data as VANC.
I have written to you a private message via this forum (so please check it, it is in your User Control Panel) with my contact details so that we can take the rest offline, but for all the samples you have provided, I believe there is a solution to output the clip including the closed captions via a Decklink card.
--
Petr Novak