This is most likely OE (operator error), but is hard to tell because all relevant details are missing. Tell us all the steps on what hardware, OS, and with which software you took with what media in what sequence under what circumstances and settings, and everything else that is relevant or even irrelevant, because you want to know why not, as an answer to a not posed question, and why yes. Makes sense?
In fact, I am hoping it's operator error.
I am using Win7, 32 bit on a laptop with an integrated video card since currently I am traveling. However, so there is no confusion, before I left, I had the same issues on a Vista, 64 bit workstation with an i7 processor and dual SLI nVidia GTX9800 cards.
Also, I had CS3 on a 32 bit machine and when I rendered out of there...no problems!
So, the sequence is only about 24 seconds long and all layers are 800x600 png files that were rendered out of 3DS Max. However, I have some title screens that were done in PP and they suffer from the same fate.
I choose FIle->Export->Media and the export menu settings shows up.
I choose Quicktime and use custom settings. 800x600 with H264, Field type set to Lower Fist, 30 fps, square pixels (1.0) and maximum bitrate 144,000
File size is shown as only 3mb. When I would render something like this out of CS3, the file size would be hundreds of megabytes with H264 and I would always go back and recompress and get really good quality.
I am very new to the CS4 workflow, so I am wondering if there is somekind of preference setting or otherwise that is causing my issues.
Number of issues here:
Integrated graphics and SLI configuration can often cause problems.
Avoid QuiRckTime on a PC.
Max bitrate of 144 Kbps is great for kitchen blenders, not for video.
For the rest of the info, look at the previously included link to the Wiki and answer the 16 questions at the end, in so far as you have not yet given that information.
Post a screenshot of your export settings.
I'll take a look at the wiki, but in the meantime, I found a workaround that was basically to use QuickTime with no
compression. Once output, the file size is similar to what I would expect...huge! then I recompress with QuickTime H264 and it looks pretty good.
I'll need to test some more to discover what performance differences there are.
Also, these vids will be viewed on a PC only and not on DVD.