Video codecs such as On2 VP6 and Sorenson Spark perform better when the frame width and height use multiples of 16. While you can use any width and height in your encoding settings, non-optimal dimensions can result in poor image quality and reduced frame rate. For the best image quality and playback, you should always use width and height dimensions that use a multiple of 4 (good), 8 (better), or 16 (best). Refer to the following tables to pick dimensions for your layout.
NOTE: Both the native encoding dimensions and the playback dimensions should be a multiple of 16. For example, if you encode your FLV file to use a frame dimension of 320×240, you should scale to a size such as 512×384.
Table 1 – 4:3 Aspect Ratio Sizes
| Best (16) | Better (8) | Good (4) |
|---|---|---|
| 640 x 480 | 608 x 456 | 624 x 468 |
| 576 x 432 | 544 x 408 | 592 x 444 |
| 512 x 384 | 480 x 360 | 560 x 420 |
| 448 x 336 | 416 x 312 | 528 x 396 |
| 384 x 288 | 352 x 264 | 496 x 372 |
| 320 x 240 | 288 x 216 | 464 x 348 |
| 256 x 192 | 224 x 168 | 432 x 324 |
| 192 x 144 | 160 x 120 | 400 x 300 |
| 128 x 96 | 368 x 276 | |
| 336 x 252 | ||
| 304 x 228 | ||
| 272 x 204 | ||
| 240 x 180 | ||
| 208 x 156 | ||
| 176 x 132 | ||
| 144 x 108 | ||
| 112 x 84 |
Table 2 – 16:9 Aspect Ratio Sizes
| Best (16) | Better (8) | Good (4) |
|---|---|---|
| 1280 x 720 | 1152 x 648 | 1216 x 684 |
| 1024 x 576 | 896 x 504 | 1088 x 612 |
| 768 x 432 | 640 x 360 | 960 x 540 |
| 512 x 288 | 384 x 216 | 832 x 468 |
| 256 x 144 | 128 x 72 | 704 x 396 |
| 576 x 324 | ||
| 448 x 252 | ||
| 320 x 180 | ||
| 192 x 108 |
Good list to have bookmarked.
Could you please explain what you say in the Note box above? It’s not clear why one would encode for one size and scale to another size when playing back the video.
Also, is there a bitrate to dimension ratio for a clear/sharp looking video? I find that the dimensions don’t really make a difference to the final encoded file size, but the bitrate makes all the difference.
I’m curious as to why 16 would be a magic number here. Also, it would be interesting to see a quick example of the difference that it makes. Is it the sort of thing where you have to squint really hard to see a possible difference or is it fairly obvious?
For example, perhaps you could show the same video at the same settings (except for dimensions) at 448×336 and 440×330. I know I could do it to satisfy my own curiosity, but if you did it, this article might have more impact for everyone.
Whatever, thanks for the insight.
Hi Rob,
Just stumbled upon your website. Qu; 4:3 at 480*384 and 16:9 at 484*272 for flash files. Would you consider this wrong or bad to use?
[...] For the best image quality and playback, you should always use width and height dimensions that use a multiple of 4 (good), 8 (better), or 16 (best). Refer to the following tables to pick dimensions for your layout
[...] For the best image quality and playback, you should always use width and height dimensions that use a multiple of 4 (good), 8 (better), or 16 (best). Refer to the following tables to pick dimensions for your layout (Courtesy of influx) [...]
Hi Robert,
I’m curious about what you’re basing this on. How did you perform your tests? Do you perceive the image quality difference or are you looking at the numbers? Does this hold true for MainConcept’s H.264?
This page is evidently simply a copy-and-paste of Adobe’s official content here: http://www.adobe.com/devnet/flash/apps/flv_bitrate_calculator/video_sizes.html
Well, it’s a copy of my content, yes. That video_sizes.html page is linked from my FLV BItrate Calculator on Adobe’s site.
[...] for VuVox, but may not be the best size for other uses. More info about resizing video for flash here. ***NOTE: Larger sizes require higher bit rates, 900 kbps is plenty for this size, but is way too [...]