Most of the mobile devices today support GPS geo tagging. In fact most of them come bundled with navigation software that uses GPS and therefore all the pictures and (maybe) videos can be geo tagged. But as expected different vendors come with different support and formats.

iPhone OS comes with geotagging both on video and image files, while the latest Android and Symbian (the Nokia main OS for smartphones) can geo tag only images.

Even more – until recently Symbian didn’t support any geotagging before the installation of an additional software – such as Location Tagger . So generally the things are quite simple:

1. iPhone OS geotags both video and image files;
2. Android geotags only images;
3. Symbian geotags only images – and on some devices this is possible only after installing a software;

This is in breve the state of mobile device geotagging!

Why Use GPS Data?

Perhaps one of the main reasons why not support geotagging especially on video files can be the usage of those geo tags. First of all what a geotag means?





You may know that even Android doesn’t “geotag” videos this is not quite true. Because after using you gallery you can see where those videos are shot. This is fantastic, but actually the real information about where the video has been taken is not into the video file, but it’s in an additional log file that keeps it. Thus actually the video files doesn’t know the geo coordinates.

Here comes the problem with video format, because you cannot be sure that every format supports tags that can keep geo coordinates. Actually quicktime’s MOV can store them, while Symbian’s 3GP cannot. In fact Symbian cannot store any geo information about video files!

So now we’ve at least three different formats for each of those three vendors.

1. quicktime for iPhone
2. mpeg-4 with Android
3. 3gp with Symbian

For now I can only say that iPhone can keep the geotag into his video files.





But let me return to the question – why we need this geo tags? Until the video file is on the mobile device – there’s no problem. But once you try to download it – whether on Flickr, YouTube, Picasa, etc. you’ll lose any geo information if it’s not into the file tags. And of course if the above sites can’t read it!

The general reason to store this data into the file is to move it along with the file. Once you move this file from your mobile device to a web platform you’ll see where the file has been created.

EXIF, Exiftool and PHP’s exif_read_data

There are several tools to read geotags. For images, and here we talk only for JPEGs, this is the EXIF information. You can download the exif command line program and try to reed data with it:

exif filename.jpg

Which can result in something like that:

Manufacturer        |Nokia                                                     
Model               |E71                                                       
Orientation         |top - left                                                
x-Resolution        |300.00                                                    
y-Resolution        |300.00                                                    
Resolution Unit     |Inch                                                      
YCbCr Positioning   |centered                                                  
Compression         |JPEG compression                                          
x-Resolution        |72.00                                                     
y-Resolution        |72.00                                                     
Resolution Unit     |Inch                                                      
FNumber             |f/3.2                                                     
Exif Version        |Exif Version 2.2                                          
Date and Time (origi|2011:01:24 12:15:01                                       
Date and Time (digit|2011:01:24 12:15:01                                       
ComponentsConfigurat|Y Cb Cr -                                                 
Aperture            |3.20 EV (f/3.0)                                           
Light Source        |0                                                         
Flash               |Flash did not fire, auto mode.                            
Focal Length        |4.9 mm                                                    
FlashPixVersion     |FlashPix Version 1.0                                      
Color Space         |sRGB                                                      
PixelXDimension     |2048                                                      
PixelYDimension     |1536                                                      
Custom Rendered     |Normal process                                            
Exposure Mode       |Auto exposure                                             
White Balance       |Auto white balance                                        
Digital Zoom Ratio  |1.00                                                      
Scene Capture Type  |Standard                                                  
GPS tag version     |0x02, 0x02, 0x00, 0x00                                    
North or South Latit|N                                                         
Latitude            |42.00, 39.00, 24.67                                       
East or West Longitu|E                                                         
Longitude           |23.00, 21.00, 28.45                                       
Altitude reference  |0x00                                                      
Altitude            |625.50 

While for video files (iPhone) exif cannot help you, this is possible through Exiftool. With it you can read even iPhone video geotags:

./exiftool filname.mov

In addition this information can be read with PHP via exif_read_data:

$info = exif_read_data('filename.jpg');
var_dump($info);

And this will give you not only standard tags, but geo tags too.

It’s really full of video sharing websites out there, but in fact almost all of them use Flash player to display their video files. This is the reality now, but with the coming of HTML5, perhaps the things are changing a bit!

First of all if you start dealing with video sharing platforms the first thing to do maybe is to find a good Flash (.flv) player and to convert all your video content in FLV.

Few things to know with Flash video players:

1. The user can play those videos only after installing the Flash Plugin to his browser;
2. The video must be encoded either in FLV (or FLash Video) or in MPEG-4 with h.264 codec. Only than the Flash player can play it;

The HTML5, which can be described as variety of new “things” in the HTML comes with a native <video> tag. Something like the <img> tag where you can just point the source of the image in the src attribute.

First Question – How Does it Look Like?

To get more fluent with the <video> tag you must simply thing of it as a “complex” <img> tag. You just point to the video and the browser will do the rest. To be more exact let me send you to the w3schools page, but the important thing as they say:

Until now, there has never been a standard for showing video on a web page.

However to start from somewhere here’s a little snippet showing you the basic, but very basic usage of the HTML5 video tag:

<video src="path_to_the_video" controls="controls"></video>

Second Question – Is Every Video Playable?

But of course not! There are different browser – different video formats. Currently there are three formats, supported by the different browsers.

1. H.264
2. VP8
3. Theora

Note that these are video codecs and a video files does not consists of only a video codec, but also of an audio codec. This makes the video file a container of several things. As you may know already H.264 is used with MPEG-4 video format, which results in .mp4 extended files, Theora is used in OGG, which are all those .ogg files out in the web, and finaly VP8 is used in WebM … or in .webm videos.

First thing to know FLV files (.flv) can also be encoded with H.264. Actually Flash player has a h.264 decoder so this makes it possible to play both .mp4 and .flv files encoded with H.264.

Second thing to notice – where are those .webm files? I’ve never seen them!

Third Question – What is WebM and VP8?

Behind WebM and VP8 is Google. This is a new video format based again on Theora. Actually it pretends to be as good in compressing as H.264, which by the way is meant to be the best. But let me take a look at Nettuts+:

VP8, a relatively new codec, is the brainchild of On2 — the same guys behind Theora. Google acquired On2 in 2010, and opened up all the underlying patents for the codec into the public domain.

WebM, the container of choice for most current browsers, utilizes VP8 for compressing its video content and Vorbis for its audio. It produces content similar in quality to H.264.

It is completely royalty free, now and for the future. On the downside, though, it has limited hardware decoding support as well as third party device/mobile support.

Final Question – How Can I Convert a Video in WebM?

This answer is given by this article, where as it is said after having the ffmpeg version >= 0.6 you simply can use this command:

ffmpeg -i girltalk.mp4 -f webm -vcodec libvpx -acodec libvorbis -aq 90 -ac 2 girltalk.webm

Conclusion

It’s interesting to see what will happen one day. There is going to be either a harmonious life in the web video field or the codecs/formats will be as much as the browser? Who knows?