for fast movies (better for motion)
rc-lookahead=50:b-adapt=2:subq=9:trellis=1:ref=4:bframes=4:direct=auto:analyse=all

for sports (better for motion & more sharp):
rc-lookahead=50:b-adapt=2:subq=9:trellis=1:ref=4:bframes=4:direct=auto:analyse=all:deblock=-1,0

I’ve pored over the individual explanations of each x264 setting, but the settings are generally explained from the perspective of “here’s how to increase compression while maintaining quality”. What settings do I use if I want to limit compression?

For example, would I choose more or less REF frames and B-frames? Would I choose a higher or lower Motion Estimation? Or, would I just turn most settings off and use a constant quality of RF=10?

If HD space isn’t an issue, I’d be inclined to be conservative with the settings (maybe even leave most at default values), and just crank up the quality setting a fair bit (under “constant quality”).

Few reasons for this – first, once you start getting into large file sizes (higher bit-rates), it starts to get hard to distinguish the copy from the source material. You don’t need the fancy tricks the encoder pulls off, because it all just plain looks good. Second, once you’re into high bit-rates, it becomes increasingly likely that a hardware player will start choking when subjected to things like a high reference frame setting. Third, if you’ve already got a high bit-rate (high quality setting), you probably don’t need the encoder taking bits from scenes it doesn’t think need them as much and reallocating them to other areas – you might notice the degradation where it took them away, and at the same time not notice the quality increase where it actually put them.

Regardless, play around a bit and do a few test samples. If you’re not concerned about HD space, just keep cranking up the quality slider until you don’t notice a difference from the source (and make sure the Roku handles it).

Thanks much

Here are some good encoding settings I’ve used for my really small rips. These rips are re-compressions of 720p x264 mid-quality rips which I downloaded. Each video is roughly 41min long and I’ve used a size of 450mb which gives perfect quality, although the source itself isn’t perfectly clean. 450mb / 41min is approximately 1500kbit/s, that’s 30% of the size used in normal 720p rips found on the internet.

http://tinyurl.com/3qyrywv

Movies like The King’s Speech look great with even less size. I got an 852kbit/s rip with 3 ref frames, me=hex, subme=7 and fast-pskip=1, but it looks perfect. Using higher settings should allow even lower bitrates, I think around 700kbit/s for low-motion movies like The King’s Speech.

If the link isn’t working:

Reference frames: 9
B-Frames: 12
CABAC: 1
8×8 Transform: 1
Weighted P-Frames: 1
Pyramidal B-Frames: Default (Normal)

Adaptive B-Frames: Optimal
Adaptive Direct Mode: Automatic
Motion Estimation Method: Uneven Multi-Hexagon
Subpixel ME & Mode Decision: 10: QPRD in all frames (requires trellis: always)
Motion Estimation Range: 64

Adaptive Quantization Strength: 0.6
Psychovisual Rate Distortion: 1 (Default)
Psychovisual Trellis: 0

Partition Type: All
Trellis: Always

Deblocking: A: -3 B: -2 (depends on source and preference. I like less blurred and a bit more noisy pictures)

Regards, Jari666