ffmpeg -r 30 -f image2 -i flawless_victory%04d.png -ss 01:02.1 -i flawless_victory.wav -b:v 3M -threads 3 flawless_victory.webm
ffmpeg version N-55922-g454a11a Copyright (c) 2000-2013 the FFmpeg developers
  built on Aug 30 2013 18:06:50 with gcc 4.7.3 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  libavutil      52. 43.100 / 52. 43.100
  libavcodec     55. 29.100 / 55. 29.100
  libavformat    55. 15.100 / 55. 15.100
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 82.102 /  3. 82.102
  libswscale      2.  5.100 /  2.  5.100
  libswresample   0. 17.103 /  0. 17.103
  libpostproc    52.  3.100 / 52.  3.100
Input #0, image2, from 'flawless_victory%04d.png':
  Duration: 00:03:14.47, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: png, rgb24, 1920x1080, 30 fps, 30 tbr, 30 tbn, 30 tbc
Guessed Channel Layout for  Input Stream #1.0 : stereo
Input #1, wav, from 'flawless_victory.wav':
  Duration: 00:04:55.42, bitrate: 1411 kb/s
    Stream #1:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16
, 1411 kb/s
File 'flawless_victory.webm' already exists. Overwrite ? [y/N] y
[libvpx @ 00000000041f6460] v1.2.0
Output #0, webm, to 'flawless_victory.webm':
  Metadata:
    encoder         : Lavf55.15.100
    Stream #0:0: Video: vp8 (libvpx), yuv420p, 1920x1080, q=-1--1, 3000 kb/s, 1k
 tbn, 30 tbc
    Stream #0:1: Audio: vorbis (libvorbis), 44100 Hz, stereo, fltp
Stream mapping:
  Stream #0:0 -> #0:0 (png -> libvpx)
  Stream #1:0 -> #0:1 (pcm_s16le -> libvorbis)