mp4 playback jerky

[vbdanl]

hi, i have been searching posts but have not yet found the answer.. i have copied my mp4 videos created on a android s2 phone to my desktop, and am trying to play them in ubuntu. they all just show a few of the frames and the sound starts and then stops all together. basically can't watch the video at all. i have vista and fedora also loaded on the same pc. both of them will play the same videos. vista plays them but seems to be slower than they appear on my android phone, but at least they play and have sound. fedora plays the videos full screen and look pretty good, but the sound is erratic. ubuntu skips most of the frames and just plays a small amount of sound. of course they play fine on my galaxy s2 android phone. they also play perfect on my windows 7 computer at work (no doubt it is newer and faster than my home computer). i have played mp3, avi, youtube, and other videos in ubuntu without problem. i tried to add mediubuntu to my repos after looking thru posts, but not sure if that is the right thing to do or not.. it did not fix the problem. thank you for any help.

[vbdanl]

i also have puppy linux installed on the same pc. the mp4 files play the video portion good, but the audio portion plays the first part, skips part of the middle, then plays the last part of the audio.. same on all of them i tried. at least the video portion looks good. in ubuntu, the video just shows a few frames, skips a lot of frames, shows a few, repeatedly to the end. probably only 20% or less of the frames actually display. sound starts at the beginning, then stops.
hope this helps. thanks again for your help.