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Compression for streaming to iphone
Hi:
What are the best compression settings if I want to stream a video to an iphone or other mobile device. I have a 12 minute video coming off the time line of FCP. I want to upload the video to my server and create a link so that the video can be scene on a mobile device.
In other words, how does youtube do it? You can see youtube videos on the iphone. Anyone know the compression settings?
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2 Replies
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First of all you don’t want to stream to an iPhone. You want progressive download. Use the wrong terminology will get you the wrong answer.
If you want a good starting point why not have a look at the iPod presets which will also work for iPhone. Other handsets may require 3GPP (and that can be Edge, GPRS, GSM, UMTS, CDMA for example) and Compressor has presets for that too under Other Workflows Mobile Devices.
Keep in mind there is no “best” as there is no single standard. What plays on iPhone may not play on other mobile devices.
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The easiest and best tools we’ve found for outputting iPhone .mp4 files is using either Handbrake (Mac & Windows versions) or MediaCoder iPhone version (Windows only). Just use the iphone presets and adjust the data rates, pixel sizes, aspect etc. as needed.
We’ve tried the iPhone presets in Carbon Coder, Procoder and a few other encoding apps and none of them output files that will properly play via progressive download. Oddly enough…they used to…until Apple updated the iPhone OS to version 3 (in July I think). But something changed with that update.
We have about 100 videos up on our site available with ipod/iphone progressive download links. On the iPhone, they load and play pretty well if you’re on wifi. They load and play reasonably well on 3G. On anything else they take forever.
On a PC or Mac, you can either left click and watch them in the psuedo streaming mode or right click and download them for your ipod (when on a PC).
Here’a a link if you want to see them.
https://www.videomi.com/portfolio_video.htm
We kept the data rates below 512kb/sec and the audio below 80kb/sec. For most of them the avg. bitrate is around 500kb/sec. You could probably go a little lower and maintain decent quality, but below 400kb/sec you start to see the compression artifacts and blockiness (at least in our tests)
Chris Blair
Magnetic Image, Inc.
Evansville, IN
http://www.videomi.com
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