Missing hex and decoded data in `.ccd` output for old broadcast recording

I attempted to run caption-inspector on an old US TV broadcast with CEA-608 captions, reproduced [from hls.js demo page](https://hls-js.netlify.app/demo/?src=https%3A%2F%2Fplayertest.longtailvideo.com%2Fadaptive%2Fcaptions%2Fplaylist.m3u8&demoConfig=eyJlbmFibGVTdHJlYW1pbmciOnRydWUsImF1dG9SZWNvdmVyRXJyb3IiOnRydWUsInN0b3BPblN0YWxsIjpmYWxzZSwiZHVtcGZNUDQiOmZhbHNlLCJsZXZlbENhcHBpbmciOi0xLCJsaW1pdE1ldHJpY3MiOi0xfQ==): https://playertest.longtailvideo.com/adaptive/captions/playlist.m3u8

I downloaded the recording using `youtube-dl`, and have attached it to this issue (in a ZIP file so GitHub doesn't try to transcode it): [cnn-live.mp4.zip](https://github.com/Comcast/caption-inspector/files/7193226/cnn-live.mp4.zip)

I was able to play back the downloaded file with captions fine in VLC:


I ran `caption-inspector` on Ubuntu 20.04 at commit 476326f08a43ce38ecd1ea58b8910d7015e80cac, and patched the `Makefile` to build with gcc 9.3 rather than `clang` (Issue #13).

I then tried to extract the CEA-608 tracks with:

```sh
mkdir /tmp/cnn
./caption-inspector -o /tmp/cnn cnn-live.mp4
cd /tmp/cnn
zip -9 cnn.zip cnn-live*
```

All outputs I got are as attached: [cnn.zip](https://github.com/Comcast/caption-inspector/files/7193227/cnn.zip)

I got a correct-looking `cnn-live-C1.608` with captions from the program:

```
00:00:00,755 - {RCL} {ENM} {ENM} {R1:C4} {R1:C4} {TO2} {TO2} "BUT HE HAD PURINA CAT CHOW" {R2:C16} {R2:C16} {TO3} {TO3} "INDOOR."
00:00:01,930 - {EOC}
```

However, `cnn-live.ccd` appears to have timestamps and fully-decoded data, but appears to be missing "hex data" and "decoded data":

```
00:00:01,049
TEXT: Ch1 - "BU"

00:00:01,091
TEXT: Ch1 - "T "

00:00:01,133
TEXT: Ch1 - "HE"

00:00:01,175
TEXT: Ch1 - " H"

00:00:01,217
TEXT: Ch1 - "AD"
```

I was able to run `caption-inspector` against a different US broadcast capture which is a little more modern (720p59.94 with CEA-608 and 708 captions) and files created with [libcaption's flv+srt tool](https://github.com/szatmary/libcaption/blob/develop/examples/flv%2Bsrt.c) (which produces possibly-not-quite-valid CEA-608 captions), and I got proper "hex data" and "decoded data":

```
00:00:01,936 F1:5468 PS:4322 PD:5468 PD:0000 XD:0000 Ch1: "Th" <-Srvc:01 G0:T|G0:h ?00?|?00? _________ Chan-1: "T" "h" <--Seq:1 P006-B02 G0Svc:01|G0Svc:01 ???-0x00|???-0x00 _________________
XD:0000 XD:0000 XD:0000 XD:0000 XD:0000 _________ _________ _________ _________ _________ _________________ _________________ _________________ _________________ _________________
TEXT: Ch1 - "Th" Svc1 - "Th"

00:00:01,952 F2:8080 XD:0000 XD:0000 XD:0000 XD:0000 F2 - NULL _________ _________ _________ _________ 608: Field 2 NULL _________________ _________________ _________________ _________________
XD:0000 XD:0000 XD:0000 XD:0000 XD:0000 _________ _________ _________ _________ _________ _________________ _________________ _________________ _________________ _________________

00:00:01,969 F1:E5F2 PS:8322 PD:6572 PD:0000 XD:0000 Ch1: "er" <-Srvc:01 G0:e|G0:r ?00?|?00? _________ Chan-1: "e" "r" <--Seq:2 P006-B02 G0Svc:01|G0Svc:01 ???-0x00|???-0x00 _________________
XD:0000 XD:0000 XD:0000 XD:0000 XD:0000 _________ _________ _________ _________ _________ _________________ _________________ _________________ _________________ _________________
TEXT: Ch1 - "er" Svc1 - "er"
```

```
00:28:17,000 F1:94AE F1:9420 F1:9140 F1:C7F2 F1:E561 Ch1 {ENM} Ch1 {RCL} Ch1 - PAC Ch1: "Gr" Ch1: "ea" Erase NonDisp Mem ResumeCaptLoading _Row:01 - White_ Chan-1: "G" "r" Chan-1: "e" "a"
F1:F420 F1:F7EF F1:F26B F1:AE80 F1:91E0 Ch1: "t " Ch1: "wo" Ch1: "rk" Ch1 - "." Ch1 - PAC Chan-1: "t" " " Chan-1: "w" "o" Chan-1: "r" "k" Channel - 1: "." _Row:02 - White_
F1:5B4C F1:6175 F1:6768 F1:F4E5 F1:F25D Ch1: "[L" Ch1: "au" Ch1: "gh" Ch1: "te" Ch1: "r]" Chan-1: "[" "L" Chan-1: "a" "u" Chan-1: "g" "h" Chan-1: "t" "e" Chan-1: "r" "]"
TEXT: Ch1 - "Great work.[Laughter]."
```