[FFmpeg-user] [flv @ 0x6378a0] Error, Invalid timestamp=0, last=0

[Access-Dev]

Hello,

I have trouble encoding a 3gp (iphone) video
  /usr/bin/ffmpeg -i "/home/mypath/uploads/407.3gp" -acodec libfaac -ar 
44100 -ab 160k -s 488x286 -b 750k -y -f flv -r 24 -async 1 
"/home/mypath/videos/407.flv"

ffmpeg version N-38475-gc266eb1 Copyright (c) 2000-2012 the FFmpeg 
developers/da                                                                                                                                 
built on Mar  6 2012 14:43:12 with gcc 4.4.5
   configuration: --enable-gpl --enable-version3 --enable-nonfree 
--enable-postproc --enable-libfaac --enable-libmp3lame 
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora 
--enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid 
--enable-x11grab --enable-shared
   libavutil      51. 41.100 / 51. 41.100
   libavcodec     54.  6.100 / 54.  6.100
   libavformat    54.  2.100 / 54.  2.100
   libavdevice    53.  4.100 / 53.  4.100
   libavfilter     2. 62.101 /  2. 62.101
   libswscale      2.  1.100 /  2.  1.100
   libswresample   0.  7.100 /  0.  7.100
   libpostproc    52.  0.100 / 52.  0.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/mypath/uploads/407.3gp':
   Metadata:
     major_brand     : 3gp4
     minor_version   : 0
     compatible_brands: 3gp4emp
     creation_time   : 2012-03-19 21:58:26
   Duration: 00:01:40.48, start: 0.000000, bitrate: 493 kb/s
     Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 16000 Hz, mono, 
s16, 31 kb/s
     Metadata:
       creation_time   : 2012-03-19 21:58:26
       handler_name    :
     Stream #0:1(und): Video: mpeg4 (Simple Profile) (mp4v / 
0x7634706D), yuv420p, 320x240 [SAR 1:1 DAR 4:3], 460 kb/s, 7.52 fps, 30 
tbr, 1k tbn, 30 tbc
     Metadata:
       creation_time   : 2012-03-19 21:58:26
       handler_name    :
Please use -b:a or -b:v, -b is ambiguous
[buffer @ 0x6489c0] w:320 h:240 pixfmt:yuv420p tb:1/1000000 sar:1/1 
sws_param:
[scale @ 0x625ce0] w:320 h:240 fmt:yuv420p -> w:488 h:286 fmt:yuv420p 
flags:0x4
Output #0, flv, to '/home/mypath/medias/videos/407.flv':
   Metadata:
     major_brand     : 3gp4
     minor_version   : 0
     compatible_brands: 3gp4emp
     creation_time   : 2012-03-19 21:58:26
     encoder         : Lavf54.2.100
     Stream #0:0(und): Video: flv1 ([2][0][0][0] / 0x0002), yuv420p, 
488x286 [SAR 143:183 DAR 4:3], q=2-31, 750 kb/s, 1k tbn, 24 tbc
     Metadata:
       creation_time   : 2012-03-19 21:58:26
       handler_name    :
     Stream #0:1(und): Audio: aac ([10][0][0][0] / 0x000A), 44100 Hz, 
mono, s16, 160 kb/s
     Metadata:
       creation_time   : 2012-03-19 21:58:26
       handler_name    :
Stream mapping:
   Stream #0:1 -> #0:0 (mpeg4 -> flv)
   Stream #0:0 -> #0:1 (aac -> libfaac)
Press [q] to stop, [?] for help
[flv @ 0x6378a0] Error, Invalid timestamp=0, last=0
Video encoding failed

Any suggestions ?

Nicolas