9/30/12

Video formatting for PowerPoint embedding

If you have problem embedding videos into your PowerPoint presentation, here's some help.
You need to convert your video to a format PowerPoint accepts. However even if you are able to embed your video and play it on your computer, it doesn't mean it will be playable on other computers. I tried quite a few combinations of video/audio format (h264, mp3, aac etc.) and found the least common denominator of video/audio format that can be embedded in PowerPoint and played on almost all windows computers is wmv2/wmav2. So here’s command for video conversion with ffmpeg:
ffmpeg -i video1.mov -vcodec wmv2 -acodec wmav2 -f asf video1.wmv
The resulting video quality is usually not very good, the images are often pixelated. To get better video quality, you need to specify bitrate:
ffmpeg -i video1.mov -b 1500k -vcodec wmv2 -acodec wmav2 -f asf video1.wmv
Here I specified 1500kbps bitrate. You can set higher bitrate. Of course it doesn’t make sense to go above the video’s original bitrate. You can find the a video’s original bitrate from ffmpeg output or on Windows, right click the video file and select “Properties” then “Details” tab. Try different bitrates and select a lower one while still maintaining an image quality. Often times, I want to keep my video (and therefore the size of PowerPoint) small by shrinking the video (e.g. 320x240) like this:
ffmpeg -i video2.mp4 -vcodec wmv2 -acodec wmav2 -f asf -s 320x240 video2.wmv
Small video has an marginal benefit besides small file size: because the image size is small, the effect of pixilation is markedly reduced. Even with smaller size, with several videos in the Powerpoint, the file can still be too large to be sent with email(gmail and yahoo mail have 25Meg limit). To solve this problem, I usually just embed small, low quality, incomplete “teaser” videos with notes and links to complete 1080p videos I (pre)uploaded on youtube. To cut a 30 second video, starts from 5 seconds at original video:
ffmpeg -i 027.MOV -ss 00:05 -t 30 -vcodec wmv2 -acodec wmav2 -f asf -s 480x270 027s.wmv
My original 1 minute 1920x1080 video is 180MB, the half-minute “teaser” video is only 1.1MB.

9/29/12

How to add watermark to animated gif

I absolutely hate seeing all those watermarks on animated gif's. What am I going to do about it? I will teach you how to add your own.
Here are the steps:
 1, make a watermark image.
 a, create an image contain your text using a drawing program(I use mspaint on windows). I usually set background (or fill with color) to black, and text color to white, and save as monochrome bmp file.
 b, open your image from Gimp(a popular free image editor), add alpha to layer, change layer name from “background” to something else. Then add layer with transparency, use the magic wand(fuzzy select) then cut the black out.
 c, resize as needed, then save as “watermark.gif”.

 2, make/get an animated gif, resize as needed (use Gimp’s “Transform Tools->Crop” and/or “Images->Scale image”), save as “input.gif”

 3, combind input gif and watermark using ImageMagick
convert input.gif -coalesce -gravity SouthEast -geometry +5+5 null: watermark.gif -layers composite -layers optimize output.gif
4, profit! (or induce gif watermark hatred)