Can't extract caption from a special type of MXF file

[sjanaCinedigmInd]

I've a MXF file, where mediainfo can find the text track but unable to extract it using ccextractor. Here is the mediainfo -- General
Complete name : test/25782-MTR001V_SD_2997_stereo_en.mxf
Format : MXF
Commercial name : DNxHD 145
Format version : 1.2
Format profile : OP-1a
Format settings : Closed / Complete
File size : 32.8 GiB
Duration : 28 min 27 s
Overall bit rate : 165 Mb/s
Frame rate : 29.970 FPS
Encoded date : 2024-07-11 13:18:53.000
Writing application : Telestream, LLC Telestream Media Framework refs/heads/release/Flip64/v8.0 e944f75f977b69171ebe4e0055852fc515a91a17

Video
ID : 2
Format : VC-3
Commercial name : DNxHD 145
Format version : Version 1
Format profile : HD@SQ
Format settings, wrapping mode : Frame
Codec ID : 0D01030102110100-0401020271030000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 145 Mb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 29.970 (30000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:2
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 2.339
Stream size : 28.9 GiB (88%)
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Audio #1
ID : 3
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #2
ID : 4
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #3
ID : 5
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #4
ID : 6
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #5
ID : 7
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #6
ID : 8
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #7
ID : 9
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #8
ID : 10
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #9
ID : 11
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #10
ID : 12
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #11
ID : 13
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #12
ID : 14
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #13
ID : 15
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #14
ID : 16
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #15
ID : 17
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Audio #16
ID : 18
Format : PCM
Format settings : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300-040202017F000000
Duration : 28 min 27 s
Bit rate mode : Constant
Bit rate : 1 152 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Frame rate : 29.970 FPS (1601.6 SPF)
Bit depth : 24 bits
Stream size : 235 MiB (1%)
Locked : Yes

Text
ID : 2-CC1
Format : EIA-608
Muxing mode : VC-3 / Nexio user data / CDP
Bit rate mode : Constant
Frame rate : 29.970 (30000/1001) FPS
Stream size : 0.00 Byte (0%)

Other #1
ID : 1-Material
Type : Time code
Format : MXF TC
Frame rate : 29.970 (30000/1001) FPS
Time code of first frame : 01:00:00;00
Time code of last frame : 01:28:27;18
Time code settings : Material Package
Time code, stripped : Yes

Other #2
ID : 1-Source
Type : Time code
Format : MXF TC
Frame rate : 29.970 (30000/1001) FPS
Time code of first frame : 01:00:00;00
Time code of last frame : 01:28:27;18
Time code settings : Source Package
Time code, stripped : Yes

Other #3
Type : Time code
Format : SMPTE TC
Muxing mode : SDTI
Frame rate : 29.970 (30000/1001) FPS
Time code of first frame : 01:00:00;00 can anyone let me know whether ccextractor can read it or not? Or is it a limitation of it?

[kaihere14]

@sjanaCinedigmInd Thanks for the detailed report and the MediaInfo dump, that's very helpful.

I dug into how ccextractor's MXF demuxer (ccx_demuxer_mxf.c) locates caption tracks, and I think I can explain what's likely happening.

CCExtractor finds captions in MXF by matching the essence container UL (a fixed byte identifier in the file's structural metadata) of each track against a small, hardcoded table. It currently only recognizes the two standard SMPTE essence-container ULs for VBI and ANC-wrapped data. Once it finds an ANC track, it fully supports parsing CDP (SMPTE 334-2) payloads out of it, including EIA-608, so the caption format itself (CDP to EIA-608) isn't the issue.

The problem is almost certainly upstream of that: MediaInfo is a much more generic metadata parser, so it can identify and label your track ("VC-3 / Nexio user data / CDP") even though the way Telestream's Nexio system wraps that CDP data in the MXF essence container may not match either of the two ULs ccextractor knows about. When that happens, ccextractor doesn't error, it just treats the track as an unrecognized/"dark" KLV element and silently skips it, which would match the "nothing gets extracted" behavior you're seeing.

So this doesn't look like a documented, intentional limitation, more that this specific vendor wrapping has never been tested against or added to ccextractor's MXF caption-track table. Since the underlying CDP/EIA-608 decoding logic already exists, this looks fixable if someone can confirm what UL the Nexio wrapping actually uses.

@cfsmp3 could you take a look? If it'd help, it might be worth asking for a small trimmed sample (just enough to cover the caption track, not the full 32GB) or a KLV/metadata dump of the caption track's essence container UL, to confirm the exact UL and add it to the recognized table