Optimal settings when each frame is the same? different, advantage, settings, material

andy

I created a video in Vegas that consists of a still image which is stretched out to match the length of the audio track. So the video consists of many identical frames. This encodes to about the same size as if the frames were different, although it encodes much faster.

I took the resulting CCE encode and zipped it with WinZip. It shrunk down to 1/20 the size. Zipping a CCE encode of material with motion hardly shrunk at all.

Are there settings I can use in CCE that will take advantage of the fact that all the frames are indentical?

The only thing you can really adjust here is the GOP structure, and this can really make a huge difference in this case.  The main thing you'd want to do is increase the length of each GOP, basically increase the number of frames per GOP. Since all frames are identical, technically all you'd need would be one GOP because you have nothing but redundant pictures.  You would be able to cut your bitrate by like 90% and not loose any quality. But of course different standards have set GOP lengths, so if you use an extreme number you will get playback problems on certain players.  The longer the GOP the more strain on the decoder. I don't think CCE lets you adjust the GOP length by very much. The only way I can see to do it is to increase the N/M setting on the GOP tab to 5. I use 2.5 so maybe later versions allow more adjustment. You may want to use something like TMPGenc, which lets you do more optimizations to the GOP structure.

Another way you can tweak the GOP structure is to increase the number of B pictures per GOP. B pictures are by far the smallest type of pictures, and since all the frames are the same, it really doesn't matter whether it is represented by a P or B picture. Like I said, I use 2.5 which doesn't allow you to tweak GOP structure by very much, maybe later versions do, I don't know. Again, you may want to use TMPGenc for encoding these sequences.

So, in CCE set your GOP sequence to M=3, M/N=5, or use another encoder and increase the number of frames and B pictures per GOP, then you can decrease bitrate without losing quality. Give it a shot.

I think it's better to use a still picture in the authoring step to do this. For instance, im Maestro, you can import a simple bitmap image and use it as a still picture, you just expand it's length on the timeline to the desired duration. This will take almost no space, most authoring programs can do something like this.