Wikipedia:Reference desk/Archives/Computing/2016 December 7

= December 7 =

Youtube removes blank space from videos
When I upload a video to youtube, YouTube removes a five second part of the video where the screen is blank (white). This is an essential part of the video, and the fact that it removes it makes the audio and video tracks out of sync. Why is this happening, and is there anything I can do to stop this happening? 83.104.62.107 (talk) 12:15, 7 December 2016 (UTC)


 * YouTube performs extensive reprocessing of video content that you upload. Usually, these changes are "invisible" to the average user, but sometimes - especially if your media file format is non-standard - it can cause problems.  Start by reviewing the audio/video sync troubleshooting guide.  You should be aware, though, that there are zillions of reasons that you might be seeing the symptom you report.  Sometimes, the root cause can be easily fixed; sometimes, it can only be fixed by extensive and difficult procedures.  We don't yet know what happened, so if you can give us some more information, we might be able to point you in a better direction to find a solution.
 * Some questions you can answer that will help us direct your search:
 * How did you create this video file? (Did you capture it using a smart-phone?  Which model?  Did you use a video editor software like iMovie or Final Cut Pro, or some other utility?)
 * In what container format is this video file? (Generally speaking, does the file end in ".mp4", ".mov", ".avi", ...)?
 * What is your audio track length, sample rate, and compression? YouTube prefers constant-bit-rate AAC.
 * What is your video track length, frame rate, and compression? YouTube prefers 30 frame-per-second H.264 video that is "exactly" matched to the audio track length.
 * If you used "other" for any of these settings, YouTube will additionally reprocess your file - its audio and video frames may be resampled, transcoded and repacked. This procedure is frequently prone to very subtle errors and is one of the most notorious causes of audio-video synchronization errors.


 * ...important note - the "preferred formats" that I listed are documented in Google's auto-generated help file - and because Google knows I'm using an Apple software system by inspecting my web browser's settings, it auto-generates a web-based help documentation session that lists their preferences for iOS and macOS systems. So: if you used Windows, Linux, or "other" to create your video, check the Google preferences for your computer or device'' by navigating directly to the URL at https://youtube.com/help - and clicking around for the Video Uploading Troubleshooting section.


 * Nimur (talk) 17:12, 7 December 2016 (UTC)
 * I'm not a betting man, but I've seen a lot of videos in my day - quantitatively, probably several standard deviations more than most video-watchers - ...so if I had to bet money on the root-cause, using only information already present in this report, here's my hypothesis: you used a crufty video editor that emplaced a single frame - the blank frame - and used a video frame rate of 1-frame-every-five-seconds (which is incredibly efficient and legal in most video compression and container formats); but on transcode, this single frame was elided, and five full seconds of av-sync error immediately accumulated. Here's my proposed solution: retake your video, or recompose it from source files, without using variable video frame-rate.  In the antiquated version, Final Cut Pro 7, you'd do this by re-rendering before uploading; in most modern editor softwares, this happens "automatically," especially when you export; in modern Final Cut Pro, you must "conform".  Your video will be larger by a non-trivial amount, but Google's transcoder will handle it better).
 * If you used Windows Movie Maker, they do some esoteric stuff with frame-rates. Carefully follow their guidelines, and export to a fixed-framerate AVI file.
 * Nimur (talk) 17:30, 7 December 2016 (UTC)

A-163 16 Port USB 3.0 Hub
I’ve been searching for the entitled product (brand new with all the extras’) for some time. I’ve even sent e-messages to some websites, they yet not messaged… Could someone provide me the link to buy this product (brand new with all the extras’) please? I'm coming up to the deadline for of order... 103.230.106.15 (talk) 20:59, 7 December 2016 (UTC)


 * I put the title of this section into Google and it gave me a few different places to buy this from. Including Amazon. † dismas †|(talk) 23:37, 7 December 2016 (UTC)
 * I can't currently create an account with Amazon and unable to contact them. Could someone please kindly let me know whether this new condition comes with all the extras along or not. 103.230.107.23 (talk) 18:51, 8 December 2016 (UTC)
 * Package Includes: 1.16 PORT USB HUB*1 2.USB data cable*1 3.DC5V/5A power adapter*1 (NOTE: Power cord: US/EU/UK/AU) Vespine (talk) 21:45, 11 December 2016 (UTC)