video out - How to use an Android phone or tablet to make a projector presentation?

I have planned for some time to use a smartphone or tablet to give scientific presentations via projector, instead of using a laptop. I'm now thinking about buying a new Android smartphone, if I can be sure that in the end I'll be able to realize this goal with it. So my main question is: What do I have to look out for in order to get a device with which I can give projector presentations?

I apologize that this question is not exactly about a concrete problem I'm faced with right now – I just don't want to purchase a costly device only to find out later that I can't do with it what I want. I therefore did some thinking and research about the possible problems, and ask you for advice on how to avoid a concrete problem to occur in the first place.

Here are some issues that occurred to me:

1. 
   

   In my experience most projector installations in lecture halls still only provide access to a VGA connector. I know that VGA as an analog signal requires D-A conversion from a digital signal, but I'm confused about how much effort this takes: Some converters have the shape of a box which needs an extra power supply, others are very small and don't need extra power. What is the difference between these different types of devices, and which kind do I need? Please note that the links are only meant as examples, I'm not asking specifically about these products.

   
   
   


2. 
   

   Again in my experience, most installed projectors do not yet support Full HD, but still need signals at resolutions like 800x600 or 1024x768. At least some HDMI-to-VGA converters appear to support downscaling from Full HD to VGA resolutions. Since I probably can't control this from the smartphone/tablet: How does it work? Can I trust that the optimal resolution is automatically negotiated between the adapter and the projector? Can I expect a decent-looking result from the downscaling, or will it be all washed out? Practically speaking: Is there a specifically named feature of such converters that I should look out for when choosing one? Again, the link is only for reference.

   
   


3. 
   

   Android apps normally have screen output optimized for the fixed, physically small screen built into the device and not the flexibility that is provided by changing the screen resolution or resizing a window on a Desktop OS. Is it a realistic goal to achieve a good presentation experience from a mobile device similar to the one from a laptop? E.g. it appears not to be possible to get Adobe Reader for Android into a proper one-page-fullscreen mode. Is there presentation software that does this better? I'm mainly thinking of presentations in pdf format.

   
   

And maybe there are caveats I'm not even thinking of?

Answer

Update 2017

Much has changed since the writing of this answer. The old answer (see edit history) is no longer the best answer to this question.

I'd recommend getting a Chromecast and using it with a VGA adapter. This gives you the benefit of giving the presentation wirelessly, instead of leaving your phone tethered to a cable.

Most modern Android phones have this capability, but double check before you purchase if this is something important for you.

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Make sure that the phone that you get has a micro-HDMI port, in addition to the traditional USB port. This will allow you to transfer video more easily.

As you noticed, there are two types of converters- the tiny ones, and the large bulky ones with a power supply. The difference is, as stated on the link you sent, that:

Unlike passive adapters Ligawo converter has a power supply, thereby allowing a built-in signal amplification and processing of the image. Provides the signal source sufficient current through HDMI This converter can also be used without power supply.

So yes, the larger ones with power supplies would probably be better in terms of signal quality, and could still be used without being plugged in. However, due to their bulk, the better signal processing (I'm not an expert on signal processing, so I don't know how large of a difference it would make- I've used the small kind, although with a laptop, and it worked perfectly fine) might not be worth it- it's up to you to decide which type is right for you.

As of how the resolution is scaled, it should work automatically for all, if not most, converters. Just double check if it says something like "Input resolution HDMI up to 1080p possible 480p - Output Resolution VGA" (from the link you sent). It shouldn't be a problem to downscale to a specific amount that you want- in the Settings -> HDMI -> HDMI Format, you should be able to change the output resolution. For more info, look here- it is two years old, but the features should still be the same with new phones running JB/KitKat.

As of the software to run, there are many free and premium solutions available in the Google Play store that will work well. If you prefer presenting with PDFs, PDF Reader or Office Suite 7 should work. However, PDFs are a somewhat unconventional presentation format (although they can work), so you should consider using actual presentation software for a better experience. Google Drive for Mobile would work well, since you could edit your presentation on a computer (or your phone) and then present it on your phone, plus it is free. You could also use Presentation Pal, or Office 2012: Presentations, or some other presentation software- there are lots out there, and there's bound to be one that works good for you. All presentation software in the play store should work well for your purpose.

I hope this helps!