MeGUI - iPhone, iPod, iPod 5.5G profile differences

[photoguy123]

I was wondering if the differences in these profiles are not necessary.

This would be understandable given they came from different contributors.

Can anyone see any reason why these options can't be unified?

http://www.hdgreetings.com/megui-ipod.png

I would love to test them myself but don't have all three devices.

Any input appreciated,
LTG

[Adub]

Dude, what?
What do you mean, "unified"? They are all separate pieces of hardware, some with totally different chips in them, so of course the encoding parameters are going to be different. The only way you could "unify" them is if you owned apple.
And maybe not even then, with share holders and what not.

[photoguy123]

What do you mean, "unified"? They are all separate pieces of hardware, some with totally different chips in them

That doesn't explain why many of these settings can't be unified.

For example consider the Trellis option, from what I've read here en.wikipedia.org/wiki/Trellis_quantization (http://en.wikipedia.org/wiki/Trellis_quantization) it doesn't seem decoder hardware specific.

So I agree something may be hardware specific, but I would bet that all of these differences are not neccessary.

Again no dis to MeGUI, as the profiles have been figured out by different contributors.

[fields_g]

That doesn't explain why many of these settings can't be unified.

For example consider the Trellis option, from what I've read here en.wikipedia.org/wiki/Trellis_quantization (http://en.wikipedia.org/wiki/Trellis_quantization) it doesn't seem decoder hardware specific.

So I agree something may be hardware specific, but I would bet that all of these differences are not necessary.

Again no dis to MeGUI, as the profiles have been figured out by different contributors.

Are you talking about some lowest common denominator like thing?

I would assume that you are able to turn off features and have it still work and that features only help.
According to your table, you could just modify the ipod version to not have no deblock, no P8x8mv, and no B8x8mv. I don't know what MEtype is..... probably will have to find a way to set this to '1' also. I would assume that this would be universally playable across these players, but I am unsure of what it will look like.

Give it a try.

[kikker]

For starters, you can simply drop the 'ipod' profile. All 5.0g ipods have the same capabilities as 5.5g ipods. All it took was a firmware upgrade on the original 5.0g to do that. The reason why deblocking is set to 'true' for the 5.0 profile is because the ipod could only handle the lower resolution of the ipod screen itself. The "5.5g firmware" allowed the ipod to playback the 640x480 vids, and the ipod couldn't quite handle the "deblock" encodes at those higher resolutions, so the 5.5 profile turned those features off.

It does seem that the iphone/touch has a beefier decoder/processor, but I can't imagine by all that much over the 5.5g. I would simply use the tried and true 5.5g ipod profile even with the iphone, as the Baseline profile Level 3.0 requirement has not changed. You could use the iphone profile to achieve a slightly smaller file size for a given video quality, but then you probably sacrifice your battery power, as the processor would have to work slightly harder to decode the stream.

With the increased resolution available on the newer ipods, your bitrate requirement would have to increase as well to achieve the same quality. I've heard it said that the bitrate should vary with the square of the change in resolution.

I think that the iphone can probably handle a lower minimum qf factor if you choose to encode with a constant -qf factor rather than a constant bitrate. I believe that the recommended value of 16 for the ipods was dropped to 12 for the iphone.

I'm curious what others use for their portable devices - constant quality (-qf or -crf) or constant bitrate?

Also, why is the max bitrate for the iphone at 12000?? It should still be at 1500, just like the ipod.

[photoguy123]

kikker thanks for your reply.

Just to make sure I understand you correctly I heard two things:
1) iPods are equally capable as 5.5 iPods with the firmware update
2) The original iPods had trouble with encoding of deblock set to true.

Do you mean that (2) is no longer a problem with the updated firmware, or were you suggesting that deblock be set to false to unify that setting?

Also you're right 12000 bit rate doesn't make sense to me for the iPhone - even if it could handle it, it's not necessary for 640 width video.

Thanks -

[kikker]

Just to be safe, for either ipod, you can use profile 5.5 for encodes either at 320 or 640, but if you want, you can select the original ipod profile as long as the encode does not exceed 320 width for a slightly smaller size and equal quality encode (or slightly better quality at the same size).