Encoder Options for mp4 Files

This file format is used on iPod, PSP and iPhone devices.

Video Compressor

mp4 files are saved using MPEG4 compression. You should choose the target device that will play your video.

Video Bitrate

Here you specify the bitrate the video is encoded at. The higher the value, the better the quality of the picture and the less artifacts (macro blocks and blurring). You should experiment with this. Please note higher values result in a larger file size.

Average bitrate is the mean bit rate, and is the main value that affects quality. Maximum bitrate should generally exceed this, but no set margin is required; the Average and Maximum bitrate can safely be the same.
Maximum bitrate is the absolute maximum. It does not majorly affect quality but some formats have set values that must not be exceeded (e.g. 10 megabits for DVD video). Sometimes if your maximum bitrate is too low then you will get macro block effects, in which case you should increase BOTH values.

Video Resolution

Contains a list of resolutions used on different devices. This is mostly an information field.

Audio Compressor

mp4 files are saved using AAC compression for sound.

Audio Bitrate

You can specify a variety of bitrates the sound will be encoded at. The higher the value the better the quality of sound.