To synchronize/sync avi, you may first install the proper avi codecs in your system. The video and audio stream in the avi container can be encoded by any codecs. So you have to try different decoders until you can preview the avi in Windows Media Player. 

Download Audio Video Synchronizer which can synchronize audio/video of an avi file. Click the Options button, select  Output Format as AVI in the following dialog box.

1. Before you launch the program, recommend to install the DivX codec. Select the Video compressor with DivX Codec.

2. The default Resolution is original size of the clip. If you want to change the resolution the clip, you can choose other resolution or Custom size.

3. Resize mode:

    Preserve aspect ratio: The video is resized to fit the target frame along one dimension, while preserving the aspect ratio. If the ratio of width to height in the image does not match the ratio in the target frame, it creates a letterbox.

    Stretch: The video is stretched to fit the target frame size in both dimensions, without preserving the aspect ratio.

    If you want to adjust the aspect ratio of the output clip, please choose the Stretch mode and change a new resolution.

4. Most audio compressors may not work well. Even they make the program crash. The program sets Microsoft ADPCM as the default audio compressor.

5. Some video compressors have not the settings dialog box.

6. If you want to change the size of output file, Please set the Encoding Bitrate in the DivX properties dialog box.  The Encoding bitrate is bigger, the picture is clearer, but the output file is bigger.

Note:

1. If you have installed DivX codec 6.x, the default maximum resolutions of the DivX are up to 720*480 at 30 fps or 720*576 at 25fps. If you want to get the higher resolution of the output video,  it is needed to change the Certification profile:

• 720HD Profile: up to1280*720 at 30 fps.
• 1080HD Profile: up to1920*1080 at 30 fps or 1280*720 at 60 fps
• Unconstrained: the video you are encoding may not be playable in DivX Certified consumer electronics devices.

2. If you want to view the converted avi file on the DVD/DIVX player or portable devices which supports DivX, you may select the resolution to Custom size in the output dialog box, enter the proper width and height for the device, select the DivX Certification profile as Mobile Profile or  qMobile Profile if necessary.

You also have to pay attention to the audio stream in avi file which the hardware player supports. If the operation system of the portable media players or mobile devices are Windows CE or Windows Mobile, they should support Microsoft ADPCM. They all support MP3 stream normally. You may try MPEG Layer-3 as Audio compressor in the program. But the MP3 encoder bundled in Windows was made in 1997, 56kbps, and not stable. If your computer has installed Fraunhofer Radium MP3 codec, the conversion will work perfectly. But Fraunhofer does not retail the compressor.

3. Some unstable video or audio compressors may produce another out of sync problem. In this case  please try to output wmv format first.

AVS is a coding method of a new generation developed by China with the independent intellectual property rights. Now China is working on the development of AVS specifications. AVS standards mainly includes 4 technical standards: system, video, audio and digital rights management. And AVS video mainly focuses on video compression applied to high definition television and high-density optical storage media.

AVC is Advanced Video Coding.

H.264 is a kind of high-performance video codec technology developed by JVT (Joint Video Team) formed by both ITU-T and ISO. So it’s not only ITU-T’s H.264 but also ISO/IEC’s MPEG-4 AVC and which nearly becomes Part 10 of the MPEG-4 standard. H.264’s biggest advantage lies in high compression ratio which will greatly help users save download time and data traffic charges. H.264 compression ratio is twice higher than MPEG-2 while 1.5 ~ 2 times than MPEG-4 under the condition of the same image quality. Besides, H.264 also provides high-quality smooth image.

To synchronize/sync AVS or AVC/H.264, please install FFDshow codec and container splitter.