This is my presentation to simplify a considerable amount of information in a way that could be useful for those who just need a basic comprehension of this subject and it could be valuable for those wanting to know more. There is a lot more to know about this.
Another consideration I want to clearly explain here is I am not encouraging illegal use of copyrights. I use Handbrake, other software and commercial movies for my personal entertainment and back ups and my intention here is to give you some information about compression for videos and movies, specifically for Apple devices.
Screen resolution and image quality on Apple devices
iPads, iPhones and the iPod Touch can play videos at higher resolution than the screens they possesses. This is useful for playback on external devices like Tv sets, monitors or projectors.
Don’t confuse playback capability with native screen display.
As an example the iPad has a 1024 × 768 pixels screen for native display. But the iPad can play 1280 x 720 HD videos on an external devices. For native video playback use the screen size as a reference for your movie. Anything bigger wont show better screen quality.
Display and Playback Specifications
iPad
1024 × 768 pixels screen, 132 ppi
9.7 inches 1.33 aspect ratio. 4:3 (4 units wide x 3 units tall)
Can play videos in Motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels, 30 frames per second.
iPhone 4
960 x 640 pixels screen at 326 ppi; 800:1 contrast ratio. 4:3 (4 units wide x 3 units tall)
89 mm (3.5 in) IPS LCD. 3:2 screen proportion (3 units wide x 2 units tall)
Can play videos in H.264 format up to 35 Mbps, 1280 by 720 pixels, 30 frames per second.
iPhone 3.0, 2.0, 1.0 and iPod Touch
480 x 320 pixels screen at 163 ppi. 18-bit 262,144 colors.
89 mm (3.5 in) LCD 3:2 aspect ratio. 3:2 screen proportion (3 units wide x 2 units tall)
Can play videos in H.264 video format up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second.
Some sources indicates the iPhone 3GS and iPhone 4 can play full HD 1080p videos.
Other video formats
DVD
640 x 480 and 720 x up to 480 and 854 x 480 pixels or points at 29.97 frames per second up to 9.8 Mbit/s (9800 kbit/s) 4:3 (4 units wide x 3 units tall). Not considered high definition.
High Definition video resolution (HD)
1080: (1920 x 1080 pixel image size) 16:9 image proportion. (16 units wide x 9 units tall).
720: (1280-720 pixel image size) 16:9 image proportion. (16 units wide x 9 units tall).
Both formats play at 24 frames per second on movies.
This image represents the iPhone 480 screen, DVD 720 image resolution, iPad screen 1024 and HD 720 image definition displayed on a HD1080 screen at 1920×1080. You can see the maximum level of detail produced from lower resolution formats up to HD 1920×1080. The square frames relates the area those formats occupy on a HD 1080 screen.
Handbrake
Handbrake is a very efficient and also a free app to convert (RIP) original DVD movies and videos into a movie file. (Use the original DVD disks). Is available for Macs and PCs. This software is no suited for video and movie transcode, or conversion from one file format to another. But consider is faster to convert DVD movies from a disk several times for different formats than the time it takes to convert a single movie file to another video format.
For video transcoding, conversion from one video file format to another, I use Quicktime Pro. But ths is a very time consuming task even on a very powerful machine. Use transcoding If you don’t have the DVD disk source or if you already have a movie file inside your computer and you want to create a smaller resolution version or file size, or the video available in another format such as .WMV for Windows Media PLayer.
There are a lot of commercial and free software available to do all kind of task with videos and is up to you to use the one you feel is right for you. I use Handbrake to get my movies from DVDs into my PC and Mac as it serves very well for this purpose.
Download Handbrake and VLC for free. If you are not sure what version to choose, get the 32 bit version of each app. If you know you have a 64 bit OS choose the 64 bit options.
This windows shows the typical movie settings for DVD conversion to Apple TV and iPads inside Handbrake. The iPad can play a video at higher resolution but because the source in this case is a DVD this is almost the best image quality you can get. I use the “Apple TV” preset for DVDs to iPad. And the “iPhone & iPod” Touch for these devices.
The typical movie file size for DVD converted movies: 1.2 – 1.6 GB for 90 min movie.
The typical movie file size for iPhone converted movies: 600 – 800 MB for 90 min movie.
Cartoon movies are on the lower size end.
120 minutes movies are 25% bigger: 2000 MB for Apple TV or iPads and 950 MB for iPhones.
Total conversion time on a dualcore 2.0: 4 hours (90 min movie).
Total conversion time on a Octacore 2.8: 22 min (90 min movie).
General Concepts
Take your time to compare this following images and understand all this information as it will guide you no matter what device you use.
25% to 30% low quality compression, no a good idea
Only if you need the space low quality is an option. But convert your movies using a lower immediate size with high quality instead.
Use constant quality over bitrate
When available use the “constant quality” setting option over the bitrate, for best image quality and file size. Movies with flat colors or very stylized and lower on details are easier on file compression. They occupy less size on your device. The opposite is true either as movies with high details and colors are harder to compress and occupy more space inside your device.
iPad (1024 x 768): Better than DVD and saves space compared to HD 1280 x 720 and 1920 x 1080
The iPad HD format offers very good image quality and saves space for more movies or files, and the quality is good even for big screens TV sets.
DVD 720 Vs HD 720
Don’t get confused: DVD720 is 720 pixels wide. HD720 is 1280 pixels wide.
480 pixel iPhone movies display blurry on HD screens
The lower iPhone/iPod Touch 480 pixel resolution with high quality maybe good even for the iPad but will always display blurry on HD screens compared to natural HD content.
Never go from a lower resolution source to a higher resolution conversion
Never convert a DVD movie to high Definition (HD 720 or 1080). No detail or color will be added but the pixel increase will increment the file size.
Use 60% image quality. 64% will add 20% bigger file size
Small increments from medium-high quality movies produce very similar images, some times very hard to tell apart, but the file size difference could increase 25-35%.
“Up to” on video playback = Max playback and not Minimum
All these devices can play lower resolution and lower bitrate videos and movies.
Never use the option for black bars
It wont allow you to scale the movie to the top iPad/iPhone screen size. You will loose this option and gain nothing for video display.
1000 words Vs 6 pictures. – See it for yourself
This image complements the resolution and image size from the iPhone, iPad and HD 720 (1280×720) formats. The iPad format starts to produce enough details and the next HD 720 (1280×720) step is close. You wont be loosing to much quality with the HD iPad format and you will definitely save space.
If you want to save space on your devices it is better an immediate lower resolution movie using high quality than a higher resolution version converted using low quality.
This image is just to illustrate high quality versions on these 2 formats. The 65% image quality is visually very hard to tell from the 60% image, but the resulting file size is close to a 30% difference.
The same movie converted on different qualities. On lower quality you loose details and color.
This image represents the area a wide screen format movie takes on a iPhone or iPad screen. Never save a movie using the black bars or you wont be able to scale the movie to full screen.
Regarding file size, the first image is the lightest with 117 Kb (simple color pattern and detail), the one in the middle is 205 Kb (low on color but high detail) and the last one is 217Kb (rich color and detail). This is to show you image complexity plays an important roll on movie conversion. Simple colored cartoon videos or movies compress to a lower file size not suffering as much. But don’t expect the same space savings from a very detailed image movie such as Harry Potter.
