.flv to .mp4??

[lanzelm]

I'm trying to upload some .flv videos to YouTube. Although I can directly drag and drop, I lost picture quality.

After doing research, I realized that it's best to extract the audio and video from the flash files and then make an .mp4 file before uploading. Everything was fine and dandy on the extraction end, but I'm not able to combine the .avi and .mp3 to make the .mp4 file. Am I going about this all wrong and is there an easier/better way to not lose picture quality?

If this makes any sense to you, I:
1) extracted .flv files into two separate files (.avi and .mp3)
2) tried to combine those two files (using a suggested downloaded application called Yamb) to make an .mp4 file
3) got an error message right before it gave me what I needed!

Basically the error message from Yamb said it had problems importing the .mp3. ???

Please help, and thanks in advance!

[bat999]

.flv files...

mediainfo first

[lanzelm]

Just downloaded that and directly tried to convert the .flv file to .mp4 The conversion "failed"...??

[Selur]

sometimes it helps to run the mp3 through delaycut, before feeding it to mp4box, on the other side sometimes delaycut simply doesn't stop processing when fed with an mp3 file