[MEncoder-users] video plays super fast if using libavcodec

[Yordan Pavlov]

Hi there,
I am having trouble recording a video out of my Ligitech UVC camera.
Actually the video is fine, but there is something about the audio which
makes the resulting video file broken.

Here is the command I use along with the output I receive during encoding

dancho at debian:~$ mencoder tv:// -tv
driver=v4l2:width=640:height=480:device=/dev/video0:adevice=hw.0,2:alsa:forceaudio
-oac lavc -ovc lavc -o FullVideo.avi
MEncoder SVN-r31475-snapshot-4.4.4 (C) 2000-2010 MPlayer Team
success: format: 9  data: 0x0 - 0x0
TV file format detected.
Selected driver: v4l2
 name: Video 4 Linux 2 input
 author: Martin Olschewski <olschewski at zpr.uni-koeln.de>
 comment: first try, more to come ;-)
v4l2: your device driver does not support VIDIOC_G_STD ioctl, VIDIOC_G_PARM
was used instead.
Selected device: UVC Camera (046d:09a1)
 Capabilites:  video capture  streaming
 supported norms:
 inputs: 0 = Camera 1;
 Current input: 0
 Current format: YUYV
v4l2: ioctl set format failed: Invalid argument
v4l2: ioctl set format failed: Invalid argument
v4l2: ioctl set format failed: Invalid argument
tv.c: norm_from_string(pal): Bogus norm parameter, setting default.
v4l2: ioctl enum norm failed: Invalid argument
Error: Cannot set norm!
Selected input hasn't got a tuner!
v4l2: ioctl set mute failed: Invalid argument
v4l2: ioctl query control failed: Invalid argument
[V] filefmt:9  fourcc:0x32595559  size:640x480  fps:15.000  ftime:=0.0667
==========================================================================
Opening audio decoder: [pcm] Uncompressed PCM audio decoder
AUDIO: 44100 Hz, 2 ch, s16le, 1411.2 kbit/100.00% (ratio: 176400->176400)
Selected audio codec: [pcm] afm: pcm (Uncompressed PCM)
==========================================================================
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
==========================================================================
Opening video decoder: [raw] RAW Uncompressed Video
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
Movie-Aspect is undefined - no prescaling applied.
[swscaler @ 0x986d280]using unscaled yuyv422 -> yuv420p special converter
videocodec: libavcodec (640x480 fourcc=34504d46 [FMP4])
Selected video codec: [rawyuy2] vfm: raw (RAW YUY2)
==========================================================================
[ac3 @ 0x98ce6c0]No channel layout specified. The encoder will guess the
layout, but it might be incorrect.
Forcing audio preload to 0, max pts correction to 0.
Writing header...1f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]
ODML: Aspect information not (yet?) available or unspecified, not writing
vprp header.
Writing header...
ODML: Aspect information not (yet?) available or unspecified, not writing
vprp header.
Pos:   0.2s      3f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]
Skipping frame!
Pos:   0.5s      9f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0
.
.
.
Flushing video frames.
Writing index...
Writing header...
ODML: Aspect information not (yet?) available or unspecified, not writing
vprp header.

Video stream:  641.923 kbit/s  (80240 B/s)  size: 904042 bytes  11.267 secs
169 frames

Audio stream:  224.000 kbit/s  (27999 B/s)  size: 314026 bytes  11.215 secs
v4l2: ioctl set mute failed: Invalid argument
v4l2: 171 frames successfully processed, 0 frames dropped.

When I try to play the resulted video file the video goes at super fast
speed, the CPU is almost 100% and I receive the usual "System slow" message
pointing me to a buggy audio driver. I have played along with options for a
couple of days and here is the result.

-nosound on playback fixes the problem. Video goes smoothly.
-oac copy and -oac pcm on encoding fixes the problem.
-lavcopts acodec=ac3/vorbis or any other does not seem to help.

Despite narrowing down the problem to something with libavcodec I am unable
to solve it so I am looking for your assistance.