[FFmpeg-user] Firefox not playing audio of webm file

[Alex Keeling]

I have a webm file created with ffmpeg which plays fine in Chromium, but
which
Firefox plays silently. I'm new to FFmpeg, so I'm quite possibly missing
something elementary.

You can see the file here: http://0xffffffff.co/test.webm

Specs:
OS: Slackware 14.0
Firefox 21.0
Chromium 24.0.1312.52 (175374)
ffmpeg 0.11.1

Console command & output:
$ ffmpeg -i MVI_9037.AVI -crf 10 -b:v 1M test.webm
ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
  built on Sep  2 2013 14:05:35 with gcc 4.7.1
  configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64
--mandir=/usr/man --disable-debug --enable-shared --disable-static
--enable-pthreads --enable-libtheora --enable-libvorbis --enable-gpl
--enable-version3 --enable-postproc --enable-swscale --enable-x11grab
--enable-avfilter --enable-gnutls --enable-libcdio --arch=x86_64
--enable-libmp3lame --enable-libx264 --enable-libvpx
  libavutil      51. 54.100 / 51. 54.100
  libavcodec     54. 23.100 / 54. 23.100
  libavformat    54.  6.100 / 54.  6.100
  libavdevice    54.  0.100 / 54.  0.100
  libavfilter     2. 77.100 /  2. 77.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
Guessed Channel Layout for  Input Stream #0.1 : mono
Input #0, avi, from 'MVI_9037.AVI':
  Metadata:
    creation_time   : 2013-05-05 15:25:02
    encoder         : CanonMVI02
  Duration: 00:00:47.43, start: 0.000000, bitrate: 14650 kb/s
    Stream #0:0: Video: mjpeg (MJPG / 0x47504A4D), yuvj422p, 640x480, 30
tbr, 30 tbn, 30 tbc
    Stream #0:1: Audio: pcm_u8 ([1][0][0][0] / 0x0001), 11024 Hz, mono, u8,
88 kb/s
[buffer @ 0x1374460] w:640 h:480 pixfmt:yuvj422p tb:33333/1000000 sar:0/1
sws_param:flags=2
[buffersink @ 0x1374940] No opaque field provided
[format @ 0x137e340] auto-inserting filter 'auto-inserted scaler 0' between
the filter 'src' and the filter 'format'
[scale @ 0x1376220] w:640 h:480 fmt:yuvj422p sar:0/1 -> w:640 h:480
fmt:yuv420p sar:0/1 flags:0x4
[aformat @ 0x13dae40] auto-inserting filter 'auto-inserted resampler 0'
between the filter 'src' and the filter 'aformat'
[aresample @ 0x13df220] chl:mono fmt:u8 r:11024Hz -> chl:mono fmt:flt
r:11024Hz
[libvpx @ 0x138a8a0] v1.1.0
Output #0, webm, to 'test.webm':
  Metadata:
    creation_time   : 2013-05-05 15:25:02
    encoder         : Lavf54.6.100
    Stream #0:0: Video: vp8, yuv420p, 640x480, q=-1--1, 1000 kb/s, 1k tbn,
30 tbc
    Stream #0:1: Audio: vorbis, 11024 Hz, mono, flt
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg -> libvpx)
  Stream #0:1 -> #0:1 (pcm_u8 -> libvorbis)
Press [q] to stop, [?] for help
[libvorbis @ 0x138b200] Que input is backward in time
frame= 1423 fps= 21 q=0.0 Lsize=    6031kB time=00:00:47.39
bitrate=1042.3kbits/s
video:5824kB audio:181kB global headers:3kB muxing overhead 0.376131%


What am I doing wrong, or is this perhaps a Firefox bug, or maybe Chromium
being loose with the spec?

Alex Keeling