View Full Version : Intermittent flash frames/garbage in .m4v project render


Sam Renkin
October 10th, 2012, 06:44 AM
I'm stumped and I hope you can help; my client needs a looping video for display on a kiosk at a franchise meeting. The file format I've decided on will be a 1280x720 .mp4 video that will loop in Quicktime on a PC connected to the 50" LCD display. Here's the problem I'm running into; the assets were given to me as .m4v files that were ripped from some DVDs using Handbrake. (Note: the source files were created internally by employees using a variety of video cameras and smart phones). The file size is actually less than SD (652x376) so I cannot size them up to 1280x720 without it looking like total crap. Since there is an "art" theme for the event, I came up with a simple solution; I found a stock image of a painter's canvas for the background, and a gilded picture frame that creates a smaller "window" for display of the video. I dropped the .m4v files into the timeline, used Pan/Crop to size them to the window, and I thought I was done. WRONG ...

There are some sync or display issues with these files that show up in the preview window and also in the final render. First, if I shrink the size of my preview window, the image disappears. This is annoying because I have 4-5 different video and audio tracks in the timeline, and I can't view them all and the preview at the same time. Second, when I render the file I get intermittent "flash frames" of diagonal lines of static garbage in a rainbow of colors. It happens usually near transitions in the video clips with sharp contrast, like a fade to black or up from black. One section that is supposed to be in black and white gets completely scrambled.

Could anyone shed some light on what's happening here?

Sam Renkin
October 10th, 2012, 06:45 AM
Sorry, should have added my hardware/software setup. Vegas Pro 11, Core i7 w/Windows 7 and 8GB RAM.

Sam Renkin
October 10th, 2012, 06:59 AM
Also, FYI the pixel size of the source files is 652x376, 624x368, 602x382, and 640x366. NO IDEA how they came up with these!!

Edward Troxel
October 10th, 2012, 09:22 AM
When I've had to use odd files, I've often started a new project, set the properties to match the clip, and then render to a known good format (which is typically DV-AVI for me). Then I can use the new render and not have to worry about issues.

Sam Renkin
October 10th, 2012, 09:28 AM
Thanks Ed - actually I've tried that with rendering new MP4 files, but the problem persists. Do you know of a situation where resizing the video using pan/crop would introduce this kind of issue?

You might know the answer to this question as well - my project output size must be 1280x720 because of the display media. So, is there a way to get these clips to appear at their native pixel size when I place them on the timeline? In other words, how do I keep Vegas from automatically enlarging them to fill the frame? I'd like to place them on screen in my project at their actual pixel size. Let me know?

Sam

Edward Troxel
October 10th, 2012, 09:32 AM
Vegas will automatically expand them full size. I use the "Logo Resize" option in Excalibur to do this. It will resize and image back to it's original size on the screen.

Seth Bloombaum
October 10th, 2012, 01:30 PM
...actually I've tried that with rendering new MP4 files, but the problem persists...
MP4 can be a pretty poor editing codec. Choose a good D.I. codec like Cineform, DNxHD, Lagarith, etc. In this case, as Edward suggested, you're working at SD resolutions and smaller, so, DV-AVI would make an excellent editing codec.