First there was text messaging--keeping in touch while exercising your thumbs. Then there was picture messaging--so your friends could see how much fun they were missing. And now there's multimedia messaging--short little video clips playing on tiny screens. Picture messaging is particularly interesting because you can cross the border from the phone network to the PC world, sending photos by email and even posting them to the Web, accessible from any device, desktop, or mobile.
But what about those little video clips? They're just big enough to be a pain to send from phone to phone, and yet so small and so short for playback on a computer screen. Even worse, mobile phone video clips can be tricky to play and edit on a computer, since they use the new and evolving MPEG-4 format. As with tiny clips from other devices, like digital cameras and camcorders (recorded on solid state memory cards), these MPEG-4 files can be struggle to work with, since they are nowhere near as well-supported as good old MPEG-1 and MPEG-2.
Apple has taken a leadership role in championing MPEG-4, and carriers like Verizon Wireless therefore explicitly recommend using the Apple QuickTime Player to play clips from mobile phones. The QuickTime Pro upgrade, for editing and exporting video, also supports editing and saving video in mobile phone formats. These formats work well in QuickTime version 6.5 on Macintosh and Windows, and continue forward into the new QuickTime 7, which also adds MPEG-4 support for advanced H.264 video compression.
In this article, I'll use the QuickTime Player to view and deconstruct clips created by several camera phones. I'll show you the details of the MPEG-4 format for mobile phones--called 3GPP--and work around some of the idiosyncrasies of how different devices create slightly different formats.
For this project, I shot video clips with three camera phones: the LG VX7000, Motorola V710, and Samsung SCH-a890, using Verizon Wireless service.
Author's note: The SCH-a890 ($169 from Verizon with online discount) is particularly interesting because it supports the faster EV-DO (Evolution Data Optimized) data service, which mean you can receive data up to ten times faster than the current 1xRTT service (averaging 400 to 700 Kbps, and peaking up to 2 Mbps), although the upload rate is still slower (40 to 60 Kbps). In addition, this phone also not only captures and plays MPEG-4 clips, but it also supports Verizon V CAST service for playing video-on-demand clips, which use the Microsoft Windows Media format.
The cameras used in mobile phones are sporting more impressive picture resolutions (the SCH-a890 shoots still images from 160 by 120 up to 1280 by 960). However, the video clips are captured at low 176 by 144 resolution, at 15 frames per second. In addition, these cameras will capture only a maximum of 15 seconds of video, all of which limits the size of the resulting files to around 180 KB.
To capture a clip on the Samsung SCH-a890, choose Multimedia from the main menu, then Camera, then Take Flix (as opposed to Take Pix, for stills). The display then shows the live video feed from the camera, with options to adjust the image quality, digital zoom, rotation, brightness, color, and flash. The camera rotates so you can shoot self-portraits while facing the display, and the video even flips automatically so you can see yourself right side up.
Then click to record a clip, again up to a maximum of 15 seconds. You can save the clip in a video gallery in the camera's local memory, send it on as a message to another phone or via email, or upload it to the Verizon Pix Place picture/video messaging Web portal.
Author's note: By the way, sending lots of text and pictures, and especially video messages, in this way makes the carriers happy, since you're either paying by the message, or signing up for more advanced unlimited plans (around $5 to $10 per month for various packages with unlimited text messages, $15 for pictures, and $20 for video messages).
More carriers are starting to offer phones with an external memory card slot, which provides a more efficient (and no-fee) path for exchanging files with a computer (as well as opening the possibility of downloading albums to the phone to use it as a portable media player). There's not much support for a direct USB wired connection in today's phones, but there is growing support for Bluetooth, not just for connecting to a wireless headset, but also for transferring files (this depends on supported phone features and carrier policies, but is getting better).
When you send a clip (or photo) by email over the Verizon Wireless network, it arrives as a message sent from your number via the Verizon portal, vzwpix.com, with the file as an attachment. The file has a .3g2 extension, for 3GPP version 2. However, since this is a relatively new format, your existing computer and video applications may not know what to do with this file.
The 3rd Generation Partnership Project (3GPP) is a collaboration of international telecommunications standards bodies, focused on 3G (3rd Generation) technical standards for the GSM (Global System for Mobile) cellular communications technology, which is especially prevalent in Europe, and used by Cingular and T-Mobile in the U.S.
A second group, the 3rd Generation Partnership Project 2 (3GPP2), is a collaboration of North American and Asian standards bodies based in Arlington, Virginia. 3GPP2 is developing 3G specifications based on the CDMA (Code Division Multiple Access) technology, used by Sprint and Verizon Wireless in the U.S.
The resulting specs are closely related, with both groups continuing to work in parallel. Their main focus is combining and extracting from existing technologies like MPEG-4 to define common, interoperable subsets that can be supported across the industry. Since these are technical collaborations (and not patent pooling groups), the specifications are freely available for downloading, although they mostly consist of references to other published standards (see www.3gpp.org/specs/specs.htm, and www.3gpp2.org/Public_html/specs).
For example, 3GPP technical specification TS 26.140 defines media formats and codecs for Multimedia Messaging Service (MMS), with reference to 59 other supporting documents. The base supported 3GPP video and audio formats are:
In comparison, the sample 3GPP2 files use MPEG-4 video with Qualcomm QCELP (Qualcomm Code Excited Linear Predictive) audio encoding. QuickTime Player Pro provides profiles for creating both 3GPP and 3GPP2 format files with these codecs.
The easiest approach for playing 3GPP files is to use Apple's QuickTime Player, bundled on the Macintosh and available as a free download for Windows. Apple has worked hard to support and promoting MPEG-4 in QuickTime 6 and beyond, and added support for 3GPP in QuickTime 6.5.
I've used the new preview release of QuickTime Player 7 for Windows to work with these files, but they also work in version 6.5. To support these formats, make sure you update to at least version 6.5.1 (use Help > Update Existing Software). In Windows Explorer, the type for .3g2 files should then be reported as "3GPP Movie Importer." (Note that auto-updating the Player may not download the 3GP support, so make sure it is installed using Edit > Preferences > QuickTime Preferences > Update Check > Update and Install Additional QuickTime Software.)
As promised, both QuickTime Player versions 6.5 and 7 were happy to open and play the .3g2 files from the Samsung SCH-a890 and Motorola V710. But they rejected the LG VX7000 files, reporting error -2041, "invalid sample description."
The next step was experimenting with renaming the working files to other possible file types: both players could still play the file when the extension was changed to .3gp--but version 6.5 rejected .3gpp as "not a file that QuickTime understands," while the newer version 7 played the file fine. Trying the more generic types did not make QuickTime happy: in version 7, renaming to .mp4 was rejected with "unknown error," and .mov was understandably identified as "not a movie file." Version 6.5 was less happy, and just failed to launch the .mov file without further comment.
The same tests with the problematic LG VX7000 files produced an interesting workaround. All the formats caused an "invalid sample description" error, except .mov--which played fine in both versions 6.5 and 7. Go figure.
Interestingly, the QuickTime Player's Movie Info dialog reports the same format for all these files, so the problem here is likely to be inconsistent implementations of the metadata stored in the file headers:
Unfortunately, we can expect these kinds of idiosyncrasies when working with "standard" files created by different products. Slight differences in the interpretation of standards, even for unneeded or redundant header information in files, can cause confusion when trying to process them.
But what about editing these files, and converting the clips for playback on other platforms? The easiest answer is Apple's QuickTime Pro. Beyond the playback features in the free QuickTime Player, Apple offers the QuickTime Pro upgrade for $29.95 (as the website notes, "why, that's just eight cents a day for a year"). You just purchase a key code online, enter the registration code in the Player, and suddenly lots of new menu options are enabled for editing and exporting clips.
QuickTime Pro, on either platform, is a wonderfully simple yet effective tool for editing clips. You can trim individual clips by adjusting in and out points, and build longer clips by simply cutting and pasting together multiple clips. (QuickTime 7 Pro for Windows is available as a quite functional Preview version, with the full version to be available by the end of summer 2005.)
For more extensive editing, you can lean on the QuickTime platform to enable more advanced applications: as Apple adds new formats to the underlying QuickTime platform, they become available to the applications that run on top of it. This happens by default on the Macintosh, since QuickTime is the base media architecture, and also works with QuickTime-aware applications under Windows--many of which therefore use QuickTime for exporting files in MPEG-4 formats.
If you want to pass 3GPP files on to other applications or systems that may not support the latest QuickTime formats, you also can use QuickTime Pro to convert these files, edit movie properties, and export the result in a wide variety of formats. QuickTime Pro is something of a universal media format converter for both Mac and Windows, supporting an amazing profusion of image, audio, and video file formats and compression codecs, as well as built-in video enhancements and effects.
For example, to pass a 3GPP file on to a traditional Windows application as an AVI file, choose Export, then "Movie to AVI," and then choose a widely available older codec like Indeo or Cinepak (this can expand the file from 178 KB for 3GPP to more like 2 MB). Use better quality for the compression to avoid introducing additional compression artifacts to the already blocky video, or even use no compression (expanding to around 20 MB).
Another possibility for MPEG-4 files is to export as a QuickTime Movie using an older codec like Sorenson Video that can be playable on a wider variety of older machines.
When mixing low-resolution 3GPP footage with standard-resolution material in a video editor, you also can enlarge the video resolution when exporting as a QuickTime movie. Use the Size option in the Movie Settings dialog to enter a new pixel width and height. Just don't be surprised if the higher-resolution video looks rather crummy, since you're blowing up very low resolution video that already has compression blocks. But hey, it's video of the moment that you were unlikely to grab in any other way.
Finally, there's moving movies in the other direction--converting your own video clips to 3GPP format to download and play on mobile phones (and other fun gadgets).
Again, QuickTime Pro provides an easy and handy solution--just choose to export as "Movie to 3G," and choose your desired format:
To make this a bit easier, QuickTime Pro offers general presets for both 3GPP and 3GPP2 (only 3GPP2 enables the lowest 96 by 80 resolution and QCELP audio).
There are also specific presets for three profiles: 3GPP (Mobile MP4) and 3GPP2 (EZmovie) at 176 by 144 and 15 fps with AMR-NB audio, and AMC (EZmovie) at 128 by 94 and 7.5 fps with QCELP audio.
Unfortunately, the mobile carriers and handset manufacturers are not particularly focused on this kind of use for their devices, and do not provide handy documentation of supported formats in these technical terms. You'll have to experiment to see what works on your specific device, obviously starting with what you learn from examining the properties of files captured on your camera phone.
And don't forget your other devices that create and play MPEG-4 files. For example, you can use your digital camera as a portable video player by downloading clips to the memory card. These are more likely to be basic MPEG-4 files, not 3GPP (for mobile phones) or the new H.264/AVC version.
Besides the 3GPP formats, QuickTime Pro provides a variety of export options for MPEG-4 video:
It also provides a preset for the ISMA version of MPEG-4--the Internet Streaming Media Alliance is another industry alliance developing standards for streaming rich media.
MPEG-4 has been slow to gather momentum as a widely supported format, delayed by licensing issues and the process of gathering industry consensus though a standardization process. Meanwhile, commercial alternatives, including Microsoft Windows Media and Real Networks RealVideo, have leapt ahead with concentrated efforts in compression technology, efficient implementations, marketing promotion, and commercial implementations. MPEG-4 now is catching up with the new improved H.264/AVC codec, and Apple's leadership with QuickTime 7.
But less visibly, tiny MPEG-4 files have been infiltrating our devices over the past few years, appearing in digital cameras, camcorders, and now mobile phones. However, these have been little more than cute little curiosities, with such short low-resolution clips, and the difficulty of doing anything more with the MPEG-4 format.
Now the possibilities are opening up. Better lenses and larger-capacity cards make it more reasonable to shoot higher-resolution and longer clips. Mobile phones make it easier to shoot and share these clips, and memory cards and Bluetooth make it more reasonable to move them around. And stronger support for MPEG-4 and 3GPP formats in tools like QuickTime Pro make it possible to edit these clips in with other kinds of footage.
Just as streaming video has exploded beyond its origins as choppy postage-stamp videos, these tiny MPEG-4 clips are growing into a more interesting part of our multimedia lives.
Return to digitalmedia.oreilly.com