Кодировка выглядит неправильно для меня.Вы уверены, что используете правильный кодек и параметры?Есть даже сообщение об ошибке.
stu@manoa:~ $ ffmpeg -i helloworld.mp4
FFmpeg version 0.6.1, Copyright (c) 2000-2010 the FFmpeg developers
built on Dec 19 2010 11:41:10 with gcc 4.2.1 (Apple Inc. build 5664)
...
[aac @ 0x12180f800]Transition from an ONLY_LONG or LONG_STOP to an EIGHT_SHORT sequence detected. If you heard an audible artifact, please submit the sample to the FFmpeg developers.
Seems stream 0 codec frame rate differs from container frame rate: 59.94 (60000/1001) -> 29.97 (2997/100)
Last message repeated 1 times
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'helloworld.mp4':
Metadata:
major_brand : M4V
minor_version : 1
compatible_brands: M4V mp42isom
show : Government Access
artist : Government Access
album : Government Access
genre : TV Shows Public Affairs
title : Government Access 01-05-11 "Government Access"
date : 2011
Duration: 00:05:01.03, start: 0.000000, bitrate: 759 kb/s
Stream #0.0(eng): Video: h264, yuv420p, 320x240 [PAR 1:1 DAR 4:3], 628 kb/s, 29.97 fps, 29.97 tbr, 29970 tbn, 59.94 tbc
Stream #0.1(eng): Audio: aac, 48000 Hz, stereo, s16, 128 kb/s
At least one output file must be specified