cable casting sync issue

[Al Marotta]

Hi Everyone. I have vsp10. I cable cast on my local access video channel a show that last about a half hour. When I view the cable cast show on my local access channel a sync problem occurs---the sound is out of sync with the picture. This only occurs about fifteen minutes into the show. The first 15 minutes are pretty much in sync. I do not have any problem with sound sync when I edit the program on my computer.There is no sync problem when I view my post show on the access channel's web site. There is no sync problem when I view, on line, the cable casting of my show in a different city. I have no way on knowing if the cable casting in these other cities to someone's residence is free of out of sync or not. The reason I'm asking for help in this matter is that when I created my first program with VSP I had the out of sync problem, after rendering on my computer. at about 10 or 15 minutes. With the help of this list I corrected the problem. But I'm wondering if I am perhaps doing something that causes my show to lose sync when cable cast over a town's system. I confess I do not understand, or pay any attention to, first clip" issues. I just go ahead and edit. Does anyone have any suggestions?

Thank you, Al Marotta

[zaphodikus]

I must say, never heard of cable cast, perhaps give us some more clues as to your equipment setup. What are you recording with and what exact streaming settings and codecs are in use. Some codecs will loose audio sync if they cannot keep up, so more clues will help. hope someone else here can give you ideas though.

[Al Marotta]

Hi Zaphodikus,
Cable casting means a video program being shown, or broadcast, over a town's local access cable channel. I don't know if they have such channels in England. It's for amateur members of the community to use. I am recording with TV studio quality equipment (in my town's tv studio) and also with some small camera video. I don't know about codec and streaming. Is that something I can control in editing or do I need to know my town's broadcasting outlet's codec and streaming numbers?
Thanks,
Al

[rwernyei]

Al,
I find people working in TV studios are overworked and put under stressful deadlines but are very passionate of their work. Have you reached out to anyone there locally at the studio about your issues or for any guidance and tips? Nowadays big streaming services have partnership requirements for cameras, sound, delivery, etc. Example - Netflix: https://partnerhelp.netflixstudios.com/ ... ge-Capture

[Al Marotta]

Hi Rwernyei,
I'm not sure if non-Americans (are you one?) understand what local access cable is. I think it exists because of some governmental ruling that big cable companies give every town in America a local channel on which town residents can produce programs. This channel has no connection to big-time entertainment cable. The people who run it are not hard-pressed professionals, they're just your average individuals that know something about video and cable tv and they help town amateurs produce programs. I've asked the very knowledgeable technician at my town's station and he has never heard of a show's losing sync after ten or fifteen minutes. But I'm wondering if perhaps the Big Brains on this list (or anyone else) might have some suspicions on how the problem arose.
Thank you,

Al

[lata]

The reason I'm asking for help in this matter is that when I created my first program with VSP I had the out of sync problem, after rendering on my computer. at about 10 or 15 minutes. With the help of this list I corrected the problem. But I'm wondering if I am perhaps doing something that causes my show to lose sync when cable cast over a town's system. I confess I do not understand, or pay any attention to, first clip" issues. I just go ahead and edit. Does anyone have any suggestions?
Thank you, Al Marotta

Reading your replies seem to indicate the out of sync is showing on the original video before you cast over the towns system, if so then the problem is with your project.
Can you give more details as to what type of videos and audio your project contains, where does the video come from. Camcorder, Iphone, downloaded from internet?
Right click your video clips and choose properties, what are they, do this for all types of video you are using.
Give us details of your Project, Settings -- Project Properties, what are they?

If the videos are using a variable frame rate then the timeline settings will be different and could cause a shift as the timeline can only be set to a constant rate, unusual things could occur.
If your videos do use a variable frame rate then the solution may be to convert the footage to a constant rate before inserting to Video Studio.

[Al Marotta]

Hi Trevor, I'm not sure if I'm misreading your first sentence. As I indicated, my show does in fact show up fine on A) my computer when it's edited B)when I go to my town's web site where my show is posted and C)when I viewed my show on-line at the same time it was being broadcast in a far-away city. Most of the show's footage is shot in a studio. The opening of the show is shot on an expensive non-studio mobile camera.. Here are some specification:the video of the studio stuff is an mpeg4 file. Video type high profile upper field first. ATTRIBUTES 24 bits 1920X1080 16.9. Video frame rate 29.970 frames per second Data rate5000kpss AUDIO mpeg AAc audio attribute 4800hz 16 bit stereo bit rate 161kps.
I don't pay any attention to first clip issues (I don't really understand what it is). Could it be the opening footage on a mobile camera screws up the rest of the project? Thanks, Al

[rwernyei]

Al,
American. Just surprised that you actually have a public venue, all our public access channels display State high school sports and government relations. As a kid in the early 80's, there was a small local TV studio that was playing all the latest music videos like MTV on UHF turning the knob to 61. We would ride our bikes down and depending on how busy they were, they'd let you in briefly to meet the the VJs. Good times. Regarding out of sync, could it possibly be that nothing is wrong and your airing time is when there is high internet traffic? As Lata said there are many contributing factors that could be the result of your issues, project settings, different media, rendering, etc. If you are using an AVCHD cam, recording to media card you'll find the STREAM folder contains .MTS, .M2TS or .TS files. Each stop capture or when file reaches size limit a new file is created automatically. Merging these files together usually requires shifting DTS to 2 or 3 frames. Depending on your software and how it handles these extra frames can create an offset resulting in out of sync issues. I personally use free program tsMuxeR. https://www.videohelp.com/software/tsMuxeR
Another thing you can do is to check your final output by demultiplexing the file separating the audio and video streams and comparing it's duration hour, minute, second, millisecond. This way you'll know if the culprit is rogue frames. You can use command line tool FFmpeg for this or choose from VideoHelp. https://www.videohelp.com/software/sect ... ltiplexers
Hope this helps.

[Al Marotta]

Hi Rwernyei,
Thanks for your good words, but it is all too complicated for me. I was sort of hoping the solution might be some adjustment that wouldn't be too complicated.
Thank you again,
Al

[lata]

Al
using the mobile footage as the first video the program shows the messages and matches the project to the phone video then yes that could/may cause a problem depending on the properties of that video, especially if using a variable frame rate.

You may be best to start a new project then add the studio recording Mpeg4 1920 x 1080 which will set the project properties, File - Save As to give the project a name.
You can now remove that video to add the Mobile opening shot.
Continue to build the project.

Share using Same as Project Settings will use the 1920 x 1080 mpeg4 properties, at least retaining the best quality for the majority of the video.

You could of course convert the mobile footage to Mpeg4 1920 x 1080, then use the new file in the main project

[zaphodikus]

I would just keep at it, and see if different broadcasts you do loose sync at a different point/duration or if it is consistent. Eventually you would find some kind of pattern if you get a few chances to broadcast some clues will eventually emerge. Indications are that the audio stream is not keeping up, which is strange since audio normally enjoys priority over video. I would ensure that the audio includes short passages of silence every few minutes, some audio compression algorithms don't keep up if you play music continuously over them for example - guessing it is compounded by the video format , so I would want to try broadcast a lower res clip and see if still happens. Loads of tips we can all learn from above, guess that's how most of us level up.

good luck.

[Al Marotta]

Thanks, gentlemen, for your help. I'll see what I can do. I just want to point out in closing that last night I viewed my show as it was streaming over the internet (that is, it was being broadcast over my town's system and on the net). It was out of sync in ten minutes or so. Once again I viewed the program from a posted version of the show on the town's web site and it was just fine.

Again, thanks,
Al