Why To Use Two-pass Encoding?

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But if you want the highest quality possible use two-pass encoding. The first pass estimates rate distortion characteristics of video using a first set of quantization parameters (often called just QPs). These estimated characteristics help to select quantization parameters for the second pass in order to minimize quality fluctuation between the frames.

Let's see how it works. For example you have a 2-minute clip. One part of it is very dynamic. To be played well it requires 2500 kbps. The other part is good at 300 kbps. Both parts are equal. Naturally you set the bitrate at 1400 kbps which seems to be enough for both parts. One-pass encoding will produce bad results as it will set 1400 kbps for both parts ignoring their differences. The first dynamic part will look too quantized. The second part will look ok but it will take too much space and lead to unwarrantable size. The fluctuation between frames will be noticeable.

Two-pass encoding will not make such mistakes. Using statistics of the 1st pass the encoder can estimate the value of each frame in bits. It results in a better distribution of bits between two parts of the video clip. The first dynamic part will get more bits while the second part will get less bits. And both will look great.

So if you converted your video with one-pass encoding and are not satisfied with the results, try Total Movie Converter. It supports both one-pass and two-pass coding.

Total Movie Converter supports these video formats: AVI, MPE, FLASH, M1V, M2V, MPEG, WMV, MPEG4, FLI, FLC, VOB, MPG, IVF, MOV, DIVX, ASF, DV, MP4, MPG, MPEG, H261, H264, YUV, Animated GIF, DIF, EA, NSV, NUT, NUV, WSV, FLX, FLV, FFM, MMF, MPV, M4V, MKV, AVS.

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