We do not need any converting tool, because converting means re-encoding, and re-encoding will result in quality loss. The only feasible way is re-mux video and audio steam in the two MP4 files for a new MP4 file, this way is a little bit similar to copy and paste the two files and create a new file, There is no quality loss.
If you want to re-mux video and audio steam in the two MP4 files for a new MP4 file, these two MP4 files MUST be in:
The same Video Demension
The same Video Frame rate
The same Audio Sample rate
The same Audio Channels
The same Video/Audio Codec
If videos is not in the same parameter, Combine to MP4 video files will be failed, or the combined file is not what you want.
Now in Recool SWF to Video Converter 2.5, we provide feature of combine mp4 videos, which will help you solve the problems like above. You can combine mp4 videos and create a single mp4 video, or insert ad at the beginning or end of the video.
1. Select MP4 format (*.mp4) on "Target Profile", For instance: select "HTML5 MP4 240p video (*.mp4)" on "Target Profile" .
2. Check "Video Codec, Video Dimension, Video Frame rate" are fixed. Especially Video Frame rate, you have to set it to a fixed value, like "24 (Film)" if frame rate is "Original".
3. Check "Audio Codec, Audio Sample rate, Audio Channels" are fixed.
4. Now you can select flash and convert Flash to MP4 as normal.
After converting Flash to MP4, MP4 videos can be combined. You can insert an ad before a MP4 video.
1. Click 
button on toolbar, open " Combine MP4 Videos" dialog:
2. Click "Add MP4" button to add MP4 Video.
3. Click "Move Up" or "Move Down" button to adjust the video sequence.
4. Click "Combine" button, input the output MP4 file name, you can combine MP4 videos now.
5.After combining MP4 video, You can view the MP4 file on the output folder.Try Free Recool SWF to Video Converter
