Greetings,

i tried to convert from yuv to m4v (MPEG-4) with ffmpeg
i type this command

ffmpeg -s cif -vcodec mpeg4 -r 30 -b 64 -g 30 -i akiyo_cif.yuv a02.m4v

but i get the following error :

ffmpeg version 0.8.9-6:0.8.9-0ubuntu0.13.04.1, Copyright (c) 2000-2013 the Libav developers
built on Nov 9 2013 19:15:52 with gcc 4.7.3
*** THIS PROGRAM IS DEPRECATED ***
This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
[rawvideo @ 0x87bd480] Estimating duration from bitrate, this may be inaccurate
Input #0, rawvideo, from 'akiyo_cif.yuv':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0.0: Video: mpeg4, yuv420p, 352x288, 30 tbr, 30 tbn, 30 tbc
[buffer @ 0x87be4c0] w:352 h:288 pixfmt:yuv420p
Output #0, ipod, to 'a02.m4v':
Stream #0.0: Video: [0][0][0][0] / 0x0000, yuv420p, 352x288, q=2-31, 200 kb/s, 90k tbn, 30 tbc
Stream mapping:
Stream #0.0 -> #0.0
Encoder (codec id 28) not found for output stream #0.0

what did i do wrong?

The error says you don't have video codec named mpeg4.

It appears you are using old Ubuntu 13 and perhaps it's ffmpeg doesn't has royalty mpeg4 video codec.

So you can build ffmpeg from source with required codecs.