Two pass encoding produces much better results than one pass encoding. But there are certain disadvantages of this technique. Two pass coding is almost twice slower than one-pass coding. So if you are short of time select one-pass solution.
Normally, the conversion of a video file is performed in 1 pass mode and when you play your video after that conversion is over you might find out the following issues:
* transitions between such scenes are rather unnatural and noticeable (due to the sharp unexpected change of a difficult frame to more statical one and vice versa);
* the most dynamic scenes turned out to consist of "square blocks" (to look smart such scenes require more bitrate value or a less quality quantizer value in comparison with those of the statical ones ).
Two pass encoding produces much better results than one pass encoding. But there are certain disadvantages of this technique. Two-pass coding is almost twice slower than one-pass coding. So if you are short of time select one-pass solution.
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 Any Video Converter. It supports both 1 pass and 2 pass encoding.
Any Video Converter converts almost all video formats including DivX, XviD, MOV, RM, RMVB, MPEG, VOB, DVD, WMV, AVI to MPEG-1, MPEG-2, MPEG-4, 3GP or FLV movie formats.
You can find the different between the same video encoded in 1 Pass Encoding and 2 Pass Encoding by the two pictures below.
1 Pass Encoding
2 Pass Encoding
Step 1 Add Video to Any Video Converter.
Step 2 Choose MPEG-2 or MP4 as output.
Step 3 Go to the right pane of the program and unfold the video options, you can set 1 or 2 Encode Pass there.
Step 4 Click Convert button to start the conversion.