AVCONV screencast audio skips

Question

I'm not having problems with audio/video not in sync. I get audio fine, and in sync. Problem is that the audio file skips. Here's my output: http://youtu.be/D2TdXnXHt8o

Here's my script:

#!/bin/sh
echo "Enter the output file name: "; read name

fullscreen=$(xwininfo -root | grep 'geometry' | awk '{print $2;}')

avconv -f alsa -i pulse -f x11grab -r 30 -s $fullscreen -i :0.0 -vcodec libx264 -acodec mp3 -preset ultrafast -threads 4 -y $name

Using Ubuntu 14.04

Answer 1

It is a shame that avconv has yet to resolve this problem, though is supposed to be an improvement to ffmpeg. On my Ubuntu 14.04 I resorted to installing ffmpeg via

sudo add-apt-repository ppa:jon-severinsson/ffmpeg
sudo apt-get update
sudo apt-get install ffmpeg

then I run ffmpeg

ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 25 -video_size 1920x1080 -i :0.0+0,0 -acodec flac -vcodec libx264 -preset ultrafast -crf 0 -threads 0 screenoutput.mkv

and audio and video are now nicely synced.

Answer 2

I encountered the exact same problem when I tried recording with this similar command (note I am trying to use the lossless screencasting video codec huffyuv instead of trying to encode straight to x264):

avconv -f alsa -i pulse -f x11grab -r 30 -s 1920x1080 -i :0.0 -vcodec huffyuv -acodec libmp3lame -ac 1 -threads auto screencast.avi

After way too much time spent experimenting, I discovered that if I set the verbosity to 'quiet', then the "skipping" or "choppiness" improves somewhat:

avconv -v quiet -f alsa -i pulse -f x11grab -r 24 -s 1920x1080 -i :0.0 -vcodec huffyuv -acodec libmp3lame -ac 1 -threads auto screencast.avi

The only way I found to fully eliminate the problem is to record video and audio separately in two instances of avconv, then kill them to stop recording:

huffyuv:

avconv -v quiet -f x11grab -r 24 -s 1920x1080 -i :0.0 -vcodec huffyuv -threads auto video.mkv & \
avconv -v quiet -f alsa -i pulse -ar 22050 -ab 32 -ac 1 -threads auto audio.mp3 &

x264:

avconv -f x11grab -r 24 -s 1920x1080 -i :0.0 -qscale 0 -vcodec libx264 -crf 26 -preset superfast -v quiet -threads auto -y 001.mkv & \
avconv -f alsa -i pulse -acodec libmp3lame -ar 22050 -ab 32 -ac 1 -threads auto -v quiet -y 001.mp3 & 

Both instances of avconv run in the background. To stop recording, kill them both at the same time with:

kill %1 %2

To stitch the audio and the video back together as one file:

avconv -i video.mkv -i audio.mp3 -c:a copy -c:v copy video_and_audio.mkv