Convert c708 /clcp from Quicktime to SRT

I have .MOV file with following info:
```
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'HTI_short.mov':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf58.76.100
timecode : 09:59:00:00
Duration: 00:25:23.00, start: 0.000000, bitrate: 2768 kb/s
Stream #0:0(eng): Data: none (tmcd / 0x64636D74)
Metadata:
handler_name : TimeCodeHandler
timecode : 09:59:00:00
Stream #0:1(eng): Video: prores (HQ) (apch / 0x68637061), yuv422p10le(tv, gbr/reserved/reserved, top coded first (swapped)), 1920x1080, 65625 kb/s, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 12800 tbn, 12800 tbc (default)
Metadata:
handler_name : VideoHandler
vendor_id : FFMP
Stream #0:2(eng): Audio: pcm_s24be (in24 / 0x34326E69), 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Stream #0:3(eng): Audio: pcm_s24be (in24 / 0x34326E69), 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Stream #0:4(eng): Audio: pcm_s24be (in24 / 0x34326E69), 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Stream #0:5(eng): Audio: pcm_s24be (in24 / 0x34326E69), 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Stream #0:6(eng): Subtitle: none (c708 / 0x38303763), 1920x1080, 18 kb/s (default)
Metadata:
handler_name : ClosedCaptionHandler
Unsupported codec with id 0 for input stream 0
Unsupported codec with id 0 for input stream 6
"format": {
"filename": "HTI_short.mov",
"nb_streams": 7,
"nb_programs": 0,
"format_name": "mov,mp4,m4a,3gp,3g2,mj2",
"format_long_name": "QuickTime / MOV",
"start_time": "0.000000",
"duration": "1523.000000",
"size": "526992491",
"bit_rate": "2768181",
"probe_score": 100,
"tags": {
"major_brand": "qt ",
"minor_version": "512",
"compatible_brands": "qt ",
"encoder": "Lavf58.76.100",
"timecode": "09:59:00:00"
}
}
}
```
I converted that to MPEG2 TS as below:

```
$ ffmpeg -i HTI_short.mov -map 0 -ac 2 -c:s copy -map 0:d -c:d copy -f mpegts HTI.ts
====================================
ffmpeg -i HTI_short.mov -map 0:v -map 0:a -ac 2 -map 0:s -c:s copy -map 0:d -c:d copy -f mpegts HTI.ts ffmpeg version 4.4.2-0ubuntu0.22.04.1 Copyright (c) 2000-2021 the FFmpeg developers

[mov,mp4,m4a,3gp,3g2,mj2 @ 0x558d4a7a5740] Could not find codec parameters for stream 6 (Subtitle: none (c708 / 0x38303763), 1920x1080, 18 kb/s): unknown codec
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Guessed Channel Layout for Input Stream #0.2 : mono
Guessed Channel Layout for Input Stream #0.3 : mono
Guessed Channel Layout for Input Stream #0.4 : mono
Guessed Channel Layout for Input Stream #0.5 : mono
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'HTI_short.mov':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf58.76.100
timecode : 09:59:00:00
Duration: 00:25:23.00, start: 0.000000, bitrate: 2768 kb/s
Stream #0:0(eng): Data: none (tmcd / 0x64636D74)
Metadata:
handler_name : TimeCodeHandler
timecode : 09:59:00:00
Stream #0:1(eng): Video: prores (HQ) (apch / 0x68637061), yuv422p10le(tv, gbr/reserved/reserved, top coded first (swapped)), 1920x1080, 65625 kb/s, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 12800 tbn, 12800 tbc (default)
Metadata:
handler_name : VideoHandler
vendor_id : FFMP
Stream #0:2(eng): Audio: pcm_s24be (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Stream #0:3(eng): Audio: pcm_s24be (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Stream #0:4(eng): Audio: pcm_s24be (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Stream #0:5(eng): Audio: pcm_s24be (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Stream #0:6(eng): Subtitle: none (c708 / 0x38303763), 1920x1080, 18 kb/s (default)
Metadata:
handler_name : ClosedCaptionHandler
File 'HTI.ts' already exists. Overwrite? [y/N] y
Stream mapping:
Stream #0:1 -> #0:0 (prores (native) -> mpeg2video (native))
Stream #0:2 -> #0:1 (pcm_s24be (native) -> mp2 (native))
Stream #0:3 -> #0:2 (pcm_s24be (native) -> mp2 (native))
Stream #0:4 -> #0:3 (pcm_s24be (native) -> mp2 (native))
Stream #0:5 -> #0:4 (pcm_s24be (native) -> mp2 (native))
Stream #0:6 -> #0:5 (copy)
Stream #0:0 -> #0:6 (copy)
Press [q] to stop, [?] for help
Output #0, mpegts, to 'HTI.ts':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
timecode : 09:59:00:00
encoder : Lavf58.76.100
Stream #0:0(eng): Video: mpeg2video (4:2:2), yuv422p(tv, unknown/reserved/reserved, top coded first (swapped)), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 90k tbn (default)
Metadata:
handler_name : VideoHandler
vendor_id : FFMP
encoder : Lavc58.134.100 mpeg2video
Side data:
cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
Stream #0:1(eng): Audio: mp2, 48000 Hz, stereo, s16, 384 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
encoder : Lavc58.134.100 mp2
Stream #0:2(eng): Audio: mp2, 48000 Hz, stereo, s16, 384 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
encoder : Lavc58.134.100 mp2
Stream #0:3(eng): Audio: mp2, 48000 Hz, stereo, s16, 384 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
encoder : Lavc58.134.100 mp2
Stream #0:4(eng): Audio: mp2, 48000 Hz, stereo, s16, 384 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
encoder : Lavc58.134.100 mp2
Stream #0:5(eng): Subtitle: none (c708 / 0x38303763), 1920x1080, 18 kb/s (default)
Metadata:
handler_name : ClosedCaptionHandler
Stream #0:6(eng): Data: none (tmcd / 0x64636D74)
Metadata:
handler_name : TimeCodeHandler
timecode : 09:59:00:00
[mpegts @ 0x558d4a8217c0] Stream 5, codec none, is muxed as a private data stream and may not be recognized upon reading.
[mpegts @ 0x558d4a8217c0] Stream 6, codec none, is muxed as a private data stream and may not be recognized upon reading.
frame= 1500 fps=123 q=31.0 Lsize= 25610kB time=00:00:59.96 bitrate=3498.6kbits/s speed= 4.9x
video:12741kB audio:11250kB subtitle:136kB other streams:0kB global headers:0kB muxing overhead: 6.144103%
```
When i am trying to extract subtitles as below, the output file is blank:
```
$ ffmpeg -f lavfi -i "movie=HTI.ts[out0+subcc]" -map 0:s HTI.ts.srt

ffmpeg version 4.4.2-0ubuntu0.22.04.1 Copyright (c) 2000-2021 the FFmpeg developers
Input #0, lavfi, from 'movie=HTI.ts[out0+subcc]':
Duration: N/A, start: 1.440000, bitrate: N/A
Stream #0:0: Video: rawvideo (Y42B / 0x42323459), yuv422p, 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 90k tbc
Stream #0:1: Subtitle: eia_608
Output #0, srt, to 'HTI.ts.srt':
Metadata:
encoder : Lavf58.76.100
Stream #0:0: Subtitle: subrip
Metadata:
encoder : Lavc58.134.100 srt
Stream mapping:
Stream #0:1 -> #0:0 (eia_608 (cc_dec) -> subrip (srt))
Press [q] to stop, [?] for help
[Parsed_movie_0 @ 0x5a615207fc40] EOF timestamp not reliable
size= 0kB time=00:00:00.00 bitrate=N/A speed= 0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)
```

I think I am converting MOV -> TS wrongly which results into this. Any pointer how can i achieve my goal of extracting captions as srt or webvtt files?