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How to work around video and subtitle embed errors
This is going to be a slightly weird tutorial. The background story is as follows. Recently, I created a bunch of sweet parody clips of the Risitas y las paelleras sketch, famous for its insane laughter by the protagonist, Risitas. As always, I had them uploaded to Youtube, but from the moment I decided on what subtitles to use to the moment when the videos finally became available online, there was a long and twisty journey.
In this guide, I would like to present several typical issues that you may encounter when creating your own media, mostly with subtitles and the subsequent upload to media sharing portals, specifically Youtube, and how you can work around those. After me.
The background story
My software of choice for video editing is Kdenlive, which I started using when I created the most silly Frankenstein clip, and it's been my loyal companion ever since. Normally, I render files to WebM container, with VP8 video codec and Vorbis audio codec, because that's what Google likes. Indeed, I had no issues with the roughly 40 different clips I uploaded in the last seven odd years.
However, after I completed my Risitas & Linux project, I was in a bit of a predicament. The video file and the subtitle file were still two separate entities, and I needed somehow to put them together. My original article for subtitles work mentions Avidemux and Handbrake, and both these are valid options.
However, I was not too happy with the output generated by either one of these, and for a variety of reasons, something was ever so slightly off. Avidemux did not handle the video codecs well, whereas Handbrake omitted a couple of lines of subtitle text from the final product, and the font was ugly. Solvable, but not the topic for today.
Therefore, I decided to use VideoLAN (VLC) to embed subtitles onto the video. There are several ways to do this. You can use the Media > Convert/Save option, but this one does not have everything we need. Instead, you should use Media > Stream, which comes with a more fully fledged wizard, and it also offers an editable summary of the transcoding options, which we DO need - see my tutorial on subtitles for this please.
Errors!
The process of embedding subtitles is not trivial. You will most likely encounter several problems along the way. This guide should help you work around these so you can focus on your work and not waste time debugging weird software errors. Anyhow, here's a small but probable collection of issues you will face while working with subtitles in VLC. Trial & error, but also nerdy design.
No playable streams
You have probably chosen weird output settings. You might want to double check you have selected the right video and audio codecs. Also, remember that some media players may not have all the codecs. Also, make sure you test on the system you want these clips to play.
Subtitles overlaid twice
This can happen if you check the box that reads Use a subtitle file in the first step of the streaming media wizard. Just select the file you need and click Stream. Leave the box unchecked.
No subtitle output is generated
This can happen for two main reasons. One, you have selected the wrong encapsulation format. Do make sure the subtitles are marked correctly on the profile page when you edit it before proceeding. If the format does not support subtitles, it might not work.
Two, you may have left the subtitle codec render enabled in the final output. You do not need this. You only need to overlay the subtitles onto the video clip. Please check the generated stream output string and delete an option that reads scodec= before you click the Stream button.
Missing codecs + workaround
This is a common bug due to how experimental codecs are implemented, and you will most likely see it if you choose the following profile: Video - H.264 + AAC (MP4). The file will be rendered, and if you selected subtitles, they will be overlaid, too, but without any audio. However, we can fix this with a hack.
One possible hack is to start VLC from command line with the --sout-ffmpeg-strict=-2 option (might work). The other and more sureway workaround is to take the audio-less video but with the subtitles overlayed and re-render it through Kdenlive with the original project video render without subtitles as an audio source. Sounds complicated, so in detail:
- Move existing clips (containing audio) from video to audio. Delete the rest.
- Alternatively, use rendered WebM file as your audio source.
- Add new clip - the one we created with embedded subtitles AND no audio.
- Place the clip as new video.
- Render as WebM again.
Using other types of audio codecs will most likely work (e.g. MP3), and you will have a complete project with video, audio and subtitles. If you're happy that nothing is missing, you can now upload to Youtube. But then ...
Youtube video manager & unknown format
If you're trying to upload a non-WebM clip (say MP4), you might get an unspecified error that your clip does not meet the media format requirements. I was not sure why VLC generated a non-Youtube-compliant file. However, again, the fix is easy. Use Kdenlive to recreate the video, and this should result in a file that has all the right meta fields and whatnot that Youtube likes. Back to my original story and the 40-odd clips created through Kdenlive this way.
P.S. If your clip has valid audio, then just re-run it through Kdenlive. If it does not, do the video/audio trick from before. Mute clips as necessary. In the end, this is just like overlay, except you're using the video source from one clip and audio from another for the final render. Job done.
More reading
I do not wish to repeat myself or spam unnecessarily with links. I have loads of clips on VLC in the Software & Security section, so you might want to consult those. The earlier mentioned article on VLC & Subtitles has links to about half a dozen related tutorials, covering additional topics like streaming, logging, video rotation, remote file access, and more. I'm sure you can work the search engine like pros.
Conclusion
I hope you find this guide helpful. It covers a lot, and I tried to make it linear and simple and address as many pitfalls entrepreneuring streamers and subtitle lovers may face when working with VLC. It's all about containers and codecs, but also the fact there are virtually no standards in the media world, and when you go from one format to another, sometimes you may encounter corner cases.
If you do hit an error or three, the tips and tricks here should help you solve at least some of them, including unplayable streams, missing or duplicate subtitles, missing codecs and the wicked Kdenlive workaround, Youtube upload errors, hidden VLC command line options, and a few other extras. Quite a lot for a single piece of text, right. Luckily, all good stuff. Take care, children of the Internet. And if you have any other requests as to what next my future VLC articles should cover, do feel liberated enough to send an email.
Cheers.
作者简介：
My name is Igor Ljubuncic. I'm more or less 38 of age, married with no known offspring. I am currently working as a Principal Engineer with a cloud technology company, a bold new frontier. Until roughly early 2015, I worked as the OS Architect with an engineering computing team in one of the largest IT companies in the world, developing new Linux-based solutions, optimizing the kernel and hacking the living daylights out of Linux. Before that, I was a tech lead of a team designing new, innovative solutions for high-performance computing environments. Some other fancy titles include Systems Expert and System Programmer and such. All of this used to be my hobby, but since 2008, it's a paying job. What can be more satisfying than that?
From 2004 until 2008, I used to earn my bread by working as a physicist in the medical imaging industry. My work expertise focused on problem solving and algorithm development. To this end, I used Matlab extensively, mainly for signal and image processing. Furthermore, I'm certified in several major engineering methodologies, including MEDIC Six Sigma Green Belt, Design of Experiment, and Statistical Engineering.
I also happen to write books, including high fantasy and technical work on Linux; mutually inclusive.
Please see my full list of open-source projects, publications and patents, just scroll down.
For a complete list of my awards, nominations and IT-related certifications, hop yonder and yonder please.
via: http://www.dedoimedo.com/computers/vlc-subtitles-errors.html
作者：Igor Ljubuncic 译者：译者ID 校对：校对者ID