create high quality video using ffmpeg

You can use the open source ffmpeg program to convert a media file from low quality to high quality format

[shellprompt]# /fullpath/to/ffmpeg/ffmpeg -i source.mp4 -c:v libx264 -crf 19 destinationfile.flv

OR

[shellprompt]# /fullpath/to/ffmpeg/ffmpeg -i source.mp4 -c:v libx264 -ar 22050 -crf 28 destinationfile.flv

Parameter explained
-crf XX is the quality of the video you are looking for. It’s between 0 and 51 (but between 17 and 23 it’s a reasonable range and the lowest the number is, the better quality the video is going to be).

For the -ar 22050 it’s for adjusting the audio sample range (audio quality). You can choose 11025, 22050 or 44100.

For many other example and details explanation refer Tutorial for FFMPEG

convert video from one format to another using ffmpeg

You can use the open source ffmpeg program to convert a media file from one format to another.

Below is an exmple:

[shellprompt]# /fullpath/to/ffmpeglibrary/ffmpeg -i InputFile.FLV OutputFile.mp3

There are various other options you can use to specify the attribute of the output file.

Here are few of the examples code http://linuxers.org/book/export/html/593

create video thumbnail using ffmpeg

You can use the open source ffmpeg program to extract a frame to use as a thumbnail for a video.

Below is an exmple:

[shellprompt]# /fullpath/to/ffmpeglibrary/ffmpeg -i InputFile.FLV -vframes 1 -an -s 400×222 -ss 30 OutputFile.jpg

-i = Inputfile name
-vframes 1 = Output one frame
-an = Disable audio
-s 400×222 = Output size
-ss 30 = Grab the frame from 30 seconds into the video