Video encoding for mobile: How do I choose FPS and bit rate?

Question

I'm going to encode a video from DVD to mobile supported format (mp4, flv, H.263). For a 320x240 screen if I choose around 600 kb/s, how would I know FPS that I want? How is the bitrate is related to FPS?

Answer 1

For a mobile phone, you need to check your manufacturer's recommended settings. There's a lot more to consider other then frame rate and bit rate (e.g. most embedded devices cannot play back videos with B-frames). If the device supports it, try to keep the frame rate the same as the source material.

If you're not sure what settings to use, there are plenty of guides on the internet. Alternatively, you can try to use some of the profiles bundled with a video encoding program (e.g. MeGUI or HandBrake).

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Frame rate is not dictated at all by bit rate, but higher frame rates at the same bit rate will result in a lower quality video (there are more frames to compress into the same amount of disk space). I wouldn't worry too much about the frame rate (again, choose as close to the source material as you can), but too high of a bit rate may cause problems with mobile devices.

Answer 2

They are not related.

FPS means how many unique frames are displayed per second on the device. Lower FPS will result in a jerky video. Higher FPS will result in a smoother video. On my Sony Ericsson W595 phone I set it to 15. You can set it higher (25) if you have a high end phone.

Bit rate means the size of a second of video in kilobits. More size = more details. Higher bit rate will look better but consume more processing power. Larger resolutions at high bit rates look good. For mobile devices, 600 kBit/s is sufficient.

Answer 3

You are going to want whatever the FPS is of the DVD you are encoding from unless you are trying to telecine (which may be necessary if your mobile device wants video in specific frames/sec). The only relation between bitrate and FPS is roughly how many bits get used ON AVERAGE to encode each frame. For example, if you have a 25FPS DVD for PAL, you're spending on average 24kbits per frame.