This is to reduce the amount of required dependencies by not strictly requiring aria2c out of the box. You can always change the downloader back to aria2c in the config.
This fixes some Subtitles having e.g., `&` instead of just `&`, but especially for special entities like `‏` which enables Right-to-Left mode on Hebrew and Arabic Subtitles.
Previously, it would show the download as fully complete after the first 1024-byte chunk was downloaded, as the Progress Bar total value was set to the amount of URLs. This is because it assumed there would be multiple URLs to download at once, and would advance the progress bar each time one of the downloads completed instead.
This changes it so that if there's only one URL to download, then it calculates the total amount of chunks to download which corrects the progress bar advances.
It normally auto-detects the format from the file extension. The supports formats are "MP4" and "WEBM". The input files to shaka-packager are currently always ".mp4", so this isn't particularly an issue.
However, I want to add this just as a pre-caution in case it isn't. This isn't an issue if the input file is another format, like WEBM, as this only controls the output format, the format devine wants, not the input and output format.
To possibly support download resuming in the future, the file names for the decrypt, repack, and change range functions were simplified and once output has finished it then deletes the original input file and re-uses the original input file path.
The file names were changed to just append `_repack`, `_decrypted`, `_full_range` etc. to the filename rather than using a duplex extension (`.repack.mp4`, `.decrypted.mp4`, `.range0.mp4`).
This is all so that code to check if the file was already downloaded can be simpler. Instead of having to check if 4x different possible file names for a completed download existed, it checks one.
This issue is common with Now TV where it for some reason parses into "two" languages. "en" and "eng". This results in one empty caption list, and one non empty caption list. The empty caption list tends to be first.
This issue causes a multitude of snowballing problems later down the codebase like when converting to SRT it will result in "MULTI-LANGUAGE SRT" header, which most programs do not recognize, like mkvmerge, causing a mux failure.
The browser to imitate can be set in the config:
For example,
```yaml
curl_impersonate:
browser: chrome110
```
It will default to using chrome110 if no value is set in the config.
A list of available Browsers are listed here: https://github.com/yifeikong/curl_cffi#sessions
This was originally done to prevent *all* aria2c logs unless on the last attempt, at which if it failed all attempts it would let aria2c log the error.
However, that's bad practice as aria2c may produce errors or warnings on say the 3rd attempt, and the 3rd attempt may have otherwise succeeded, with warnings or errors. It also generally shouldn't be necessary.
The original values would cause blocks by some Services. Therefore, it is better to default to safer values. The new values match the defaults used by aria2c as listed in their docs.
For downloads by devine, there's generally no reason to retrieve this information when it will be decrypted, repacked, remuxed, and so on anyway. Requesting the timestamp will just mean more requests being made, perhaps slowing down the download.
This was added by another team member a long time ago, seemingly for the purposes of preventing a split on DASH/HLS segment files, as they would be already quite small.
However, just because they are small it isn't exactly a problem to have it split, and it would only split if the segment file size fits the default split size of 20M at least twice. I.e., if the segment is 45M, it will split twice. If the segment is 25M, it actually won't split at all. You may think 25M will split by 20M into two downloads, but actually the split size must explicitly fit for it to split. So for 2 downloads it will need to be 40MB in size, then 60, then 80, and so on.
A 40M or bigger segment file does in my opinion deserve to be split as it may genuinely reap speed benefits.
If the Server returns a Content-Length Header with a value of 0, then the code near-after it would end up looping response streamed chunks of 0-length size, which would go on forever.
This is seen in some manifests/services for whatever reason. I can't find documentation for this value anywhere. It seems unused in official specifications as of right now. However, it seems in some services/places it is unofficially used as a PAL-version of BT-601 transfer, which makes sense.
Devine's code (and other services) wouldn't care about the difference here so currently it is just implemented as a remap from 5 to 6. In the future it may be changed and actually defined as two seperate BT_601 Transfer enum entries.
This also bypasses the warning log about the audio likely being part of an invariant playlist, which may be true it is too specific of a warning when it could be multiple other reasons why.
Ok, so there's a few reasons this was done.
1) Design-wise it isn't valid to have --proxy (or via config/otherwise) set a proxy, then unpredictably have it bypassed or disabled. If I specify `--proxy 127.0.0.1:8080`, I would expect it to use that proxy for all communication indefinitely, not switch in and out depending on the track or service.
2) With reason 1, it's also a security problem. The only reason I implemented it in the first place was so I could download faster on my home connection. This means I would authenticate and call APIs under a proxy, then suddenly download manifests and segments e.t.c under my home connection. A competent service could see that as an indicator of bad play and flag you.
3) Maintaining this setup across the codebase is extremely annoying, especially because of how proxies are setup/used by Requests in the Session. There's no way to tell a request session to temporarily disable the proxy and turn it back on later, without having to get the proxy from the session (in an annoying way) store it, then remove it, make the calls, then assuming your still in the same function you can add it back. If you're not in the same function, well, time for some spaghetti code.
---
tldr; -1 ux/design/expectations with CLI, -1 security aspect, -1 code maintenance, but only +1 for potentially increased download speeds in certain scenarios.
Services needing this done should apply it themselves, e.g. OnMultiplex. A convenience function to do it is available now as `Subtitle.remove_multi_lang_srt_header()`, so you can do e.g., `subtitle.OnMultiplex = remove_multi_lang_srt_header` and it will pass through this function just before muxing.
On Windows it seems to default to some encoding other than UTF-8 (possibly UTF-16 or CP-1252) and since the chapter file is saved as UTF-8, it breaks characters outside typical range. Like ø, æ, and other stuff.
rlaphoenix