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The article says that "Subtitle files... are not encrypted". Netflix subtitles are really interesting to me, because they're aligned in different languages. A l

The article says that "Subtitle files... are not encrypted". Netflix subtitles are really interesting to me, because they're aligned in different languages. A lot of unofficial SRT files have different timestamps. The reason is that I'm trying to collect data for learning languages, especially Chinese. Kind of like VoiceTube [1] and Youglish [2] are doing for English. So far it's only for personal use, not a revenue-taking company. I tried investigating a Netflix stream, but the subtitles weren't plain text! They were distributed as PNG files [3]. Does anyone have more information about this? Do the pirates really OCR the subtitles for their MKV files? (I doubt it). Is there another way to get the plain text? Contact me directly if you're afraid to comment publicly. [1] https://www.voicetube.com/ https://www.voicetube.com/ [2] https://youglish.com/ https://youglish.com/ [3] https://www.slideshare.net/RohitPuri23/timed-text-at-netflix-58522643 https://www.slideshare.net/RohitPuri23/timed-text-at-netflix...

invokestatic 7y ago
I wonder if Netflix’s use of image subtitles is a carryover of how subtitles work on DVDs — images as well.
- slhck 7y ago
  It's not a carry-over from their DVD business. It's a consequence of how they choose to stream. My assumption is that image-based subtitles are more compatible across a range of devices and clients, as you get to choose how they look beforehand. You can definitely send subtitles as raw text and metadata – it's what they do on iOS devices IIRC, since you can change the subtitle appearance on the client. Also, their ingest works with TTML (a text-based format): https://partnerhelp.netflixstudios.com/hc/en-us/articles/215758617-Timed-Text-Style-Guide-General-Requirements https://partnerhelp.netflixstudios.com/hc/en-us/articles/215... – this is a fairly widely used standard.
denkmoon 7y ago
>Do the pirates really OCR the subtitles for their MKV files? Yes. At least as far as I have seen, which is not scene level but in private tracker discussion forums. OCR-ing digital text is pretty accurate afaik.
- peterburkimsher 7y ago
  OCR-ing ASCII text is bearable. I've tried Tesseract and get about 80% accuracy for English. But not Chinese. That's about 40% at best. The only decent OCR for Chinese I've used is Google Cloud Vision, and that costs money.
nemanjaboric 7y ago
This is similar to idx/sub files from DVD which are just images and they are OCRd to text sub/srt file. I assume it's just easier for them to render the image than to mess up with text rendering/code page issues/whatever complication coming from huge diversity of devices they support.
thaumasiotes 7y ago
> I'm trying to collect data for learning languages, especially Chinese Viki has a lot of subtitled Chinese shows. They generally don't offer Chinese subtitles for the Chinese shows though. The show itself often will, but those subtitles are just part of the video, not even an overlay.
- peterburkimsher 7y ago
  Yeah, I really need to be able to grep for a specific word to make videos like this: https://www.youtube.com/playlist?list=PLhIooD7mFhphhT5nDdhK00wZuobGbMtO0 https://www.youtube.com/playlist?list=PLhIooD7mFhphhT5nDdhK0...
superpermutat0r 7y ago
> The reason is that I'm trying to collect data for learning languages, especially Chinese. Subtitles sites (opensubtitles, podnapisi, etc.) have similar data and simple alignment algorithms will work for unaligned subtitles. > Do the pirates really OCR the subtitles for their MKV files? OCR is really simple for text. No reason why they wouldn't do it. There were free programs decades ago for OCR when you were ripping DVDs and they worked mostly on character patterns (you would start with an empty database and then just tag the pattern, after a minute you'd have the whole subtitle OCR-ed).
- peterburkimsher 7y ago
  Please can you recommend a "simple alignment algorithm"? I can send some example ENG&CHT subtitles your way. There's a different number of subtitles, shown at different times, breaking lines in different places. It's a mess. If you know how to align it quickly, please tell me! Doing it manually takes me a couple of hours: longer than the whole movie. That's why I've only done it for a very few, specifically for movie nights with friends.
  - superpermutat0r 7y ago
    You need good dictionaries, giving you all possible translations of a word both ways. Given that subtitles in both languages will have matching sentences very closely you can easily determine (be it some counting criteria, simple linear model or dynamic programming) which sequence of let's say 3 subtitle lines matches a sequence of 5 subtitle lines in the other translation. People/place/town names align stuff pretty easily. The fact that a sequence of lines matches some other sequence of lines makes finding the optimal alignment very efficient too. I'm guessing that just making a set of words for each subtitle line, counting the common words and picking a criteria of deciding if line maps to other line is more than enough. Subtitles are much easier than free-flowing documents because they are time constrained.
    - peterburkimsher 7y ago
      Please show me your best transcriptions for this channel [1]. There's over 2 TB of video data. No way to get access to the original PPT files. At least the subtitles on there are already aligned English & Chinese, but they do require OCR. Message me directly if you want my OpenCV script that can pull the yellow text out. Tesseract gave me this. The W0「d n! Gnd has bP〔‥mE ‥任Sh 嬰孩降生道咸肉員 Peace has Come for O… Km… 峒﹏m US 靜安來自‵我君手 ` I'm sorry to continue insisting, but seriously, Tesseract gave me terrible results. Identical lines don't even give the same OCR result, so trying to run partial matches on Google Translate-quality word equivalents isn't going to cut it. The OCR can't even give me the right number of characters! In the end I'm trying to do it manually, but it's really time-consuming. [1] https://www.youtube.com/channel/UC8_emPVKZvOwJnoBVpU0ytg/videos?view=0&sort=dd&shelf_id=1 https://www.youtube.com/channel/UC8_emPVKZvOwJnoBVpU0ytg/vid...
gsich 7y ago
https://nikse.dk/SubtitleEdit https://nikse.dk/SubtitleEdit uses tesseract as one method for OCR. Sometimes there are errors, like I and l but there is a "correct common errors" mode you can use.
- peterburkimsher 7y ago
  Please can you help me try to extract the subtitles from this channel? [1] Tesseract gave me this. The W0「d n! Gnd has bP〔‥mE ‥任Sh 嬰孩降生道咸肉員 Peace has Come for O… Km… 峒﹏m US 靜安來自‵我君手 ` That kind of error ratio isn't in the realm of "correcting common errors". Surely there must be better software, but I can't find anything that runs locally and can read these subtitles. I've resorted to typing them out by hand, which is super slow because I don't yet speak Chinese, so I have to use handwriting recognition to enter each character. [1] https://www.youtube.com/channel/UC8_emPVKZvOwJnoBVpU0ytg/videos?view=0&sort=dd&shelf_id=1 https://www.youtube.com/channel/UC8_emPVKZvOwJnoBVpU0ytg/vid...
  - gsich 7y ago
    You probably need to preprocess the subtitles before feeding it to Tesseract. Crop them to size, use some thresholds to only get the subtitle in the image. Seperate by languages.

invokestatic 7y ago

I wonder if Netflix’s use of image subtitles is a carryover of how subtitles work on DVDs — images as well.

slhck 7y ago
It's not a carry-over from their DVD business. It's a consequence of how they choose to stream. My assumption is that image-based subtitles are more compatible across a range of devices and clients, as you get to choose how they look beforehand. You can definitely send subtitles as raw text and metadata – it's what they do on iOS devices IIRC, since you can change the subtitle appearance on the client. Also, their ingest works with TTML (a text-based format): https://partnerhelp.netflixstudios.com/hc/en-us/articles/215758617-Timed-Text-Style-Guide-General-Requirements https://partnerhelp.netflixstudios.com/hc/en-us/articles/215... – this is a fairly widely used standard.

denkmoon 7y ago

>Do the pirates really OCR the subtitles for their MKV files? Yes. At least as far as I have seen, which is not scene level but in private tracker discussion forums. OCR-ing digital text is pretty accurate afaik.

peterburkimsher 7y ago
OCR-ing ASCII text is bearable. I've tried Tesseract and get about 80% accuracy for English. But not Chinese. That's about 40% at best. The only decent OCR for Chinese I've used is Google Cloud Vision, and that costs money.

nemanjaboric 7y ago

This is similar to idx/sub files from DVD which are just images and they are OCRd to text sub/srt file. I assume it's just easier for them to render the image than to mess up with text rendering/code page issues/whatever complication coming from huge diversity of devices they support.

thaumasiotes 7y ago

> I'm trying to collect data for learning languages, especially Chinese Viki has a lot of subtitled Chinese shows. They generally don't offer Chinese subtitles for the Chinese shows though. The show itself often will, but those subtitles are just part of the video, not even an overlay.

peterburkimsher 7y ago
Yeah, I really need to be able to grep for a specific word to make videos like this: https://www.youtube.com/playlist?list=PLhIooD7mFhphhT5nDdhK00wZuobGbMtO0 https://www.youtube.com/playlist?list=PLhIooD7mFhphhT5nDdhK0...

superpermutat0r 7y ago

> The reason is that I'm trying to collect data for learning languages, especially Chinese. Subtitles sites (opensubtitles, podnapisi, etc.) have similar data and simple alignment algorithms will work for unaligned subtitles. > Do the pirates really OCR the subtitles for their MKV files? OCR is really simple for text. No reason why they wouldn't do it. There were free programs decades ago for OCR when you were ripping DVDs and they worked mostly on character patterns (you would start with an empty database and then just tag the pattern, after a minute you'd have the whole subtitle OCR-ed).

peterburkimsher 7y ago
Please can you recommend a "simple alignment algorithm"? I can send some example ENG&CHT subtitles your way. There's a different number of subtitles, shown at different times, breaking lines in different places. It's a mess. If you know how to align it quickly, please tell me! Doing it manually takes me a couple of hours: longer than the whole movie. That's why I've only done it for a very few, specifically for movie nights with friends.
- superpermutat0r 7y ago
  You need good dictionaries, giving you all possible translations of a word both ways. Given that subtitles in both languages will have matching sentences very closely you can easily determine (be it some counting criteria, simple linear model or dynamic programming) which sequence of let's say 3 subtitle lines matches a sequence of 5 subtitle lines in the other translation. People/place/town names align stuff pretty easily. The fact that a sequence of lines matches some other sequence of lines makes finding the optimal alignment very efficient too. I'm guessing that just making a set of words for each subtitle line, counting the common words and picking a criteria of deciding if line maps to other line is more than enough. Subtitles are much easier than free-flowing documents because they are time constrained.
  - peterburkimsher 7y ago
    Please show me your best transcriptions for this channel [1]. There's over 2 TB of video data. No way to get access to the original PPT files. At least the subtitles on there are already aligned English & Chinese, but they do require OCR. Message me directly if you want my OpenCV script that can pull the yellow text out. Tesseract gave me this. The W0「d n! Gnd has bP〔‥mE ‥任Sh 嬰孩降生道咸肉員 Peace has Come for O… Km… 峒﹏m US 靜安來自‵我君手 ` I'm sorry to continue insisting, but seriously, Tesseract gave me terrible results. Identical lines don't even give the same OCR result, so trying to run partial matches on Google Translate-quality word equivalents isn't going to cut it. The OCR can't even give me the right number of characters! In the end I'm trying to do it manually, but it's really time-consuming. [1] https://www.youtube.com/channel/UC8_emPVKZvOwJnoBVpU0ytg/videos?view=0&sort=dd&shelf_id=1 https://www.youtube.com/channel/UC8_emPVKZvOwJnoBVpU0ytg/vid...

gsich 7y ago

https://nikse.dk/SubtitleEdit https://nikse.dk/SubtitleEdit uses tesseract as one method for OCR. Sometimes there are errors, like I and l but there is a "correct common errors" mode you can use.

peterburkimsher 7y ago
Please can you help me try to extract the subtitles from this channel? [1] Tesseract gave me this. The W0「d n! Gnd has bP〔‥mE ‥任Sh 嬰孩降生道咸肉員 Peace has Come for O… Km… 峒﹏m US 靜安來自‵我君手 ` That kind of error ratio isn't in the realm of "correcting common errors". Surely there must be better software, but I can't find anything that runs locally and can read these subtitles. I've resorted to typing them out by hand, which is super slow because I don't yet speak Chinese, so I have to use handwriting recognition to enter each character. [1] https://www.youtube.com/channel/UC8_emPVKZvOwJnoBVpU0ytg/videos?view=0&sort=dd&shelf_id=1 https://www.youtube.com/channel/UC8_emPVKZvOwJnoBVpU0ytg/vid...
- gsich 7y ago
  You probably need to preprocess the subtitles before feeding it to Tesseract. Crop them to size, use some thresholds to only get the subtitle in the image. Seperate by languages.