[Nottingham] mp4 playback audio slippage (loss of sync)

Mike Martin mike at redtux.org.uk
Wed Sep 12 18:49:22 UTC 2012


On 11 September 2012 22:06, Dan Caseley <dan at caseley.me.uk> wrote:
> I was joining avi video files a good while back and had the same sound
> problems. I have this script left over in my bag of tricks. I almost
> certainly pinched it from a forum somewhere because I really don't know what
> I'm doing with video content.
>
> #!/bin/bash
> for f in *_full.avi
> do
> OUTF=$(echo "$f" | sed "s/.avi/_final.avi/g")
> mencoder -forceidx -oac copy -ovc copy "$f" -o "$OUTF"
> done
>
>
> HTH,
>
> Dan
>
>
> On 11 September 2012 21:40, Nick Leverton wrote:
>
>> On Tue, Sep 11, 2012 at 09:24:41PM +0100, Jason Irwin wrote:
>> > On 11/09/12 19:53, Martin wrote:
>> > > cat file??.mp4 >video.mp4
>> > Shouldn't you be using ffmpeg or something?  I'll confess to only using
>> > it for basic transcoding.
>> >
>> > Kdenlive?  Kino?  LiVES?
>> > http://kdenlive.org/
>> > http://kinodv.org/
>> > http://lives.sourceforge.net/
>> >
>> > The easiest thing might be to keep the vids as separate files and just
>> > use a playlist.
>> >
>> > Heck, VLC can take a playlist and spit out a single, contiguous file.
>> > Won't let you do all the fancy-shmancy levelling of the others; but
>> > should do it if you are in a bind.
>>
>> If just display is wanted then Xine has good playlist behaviour, we
>> used to use it (minus GUI) at the last place I worked for displaying
>> video adverts.  We did the playlists programmatically but I believe
>> there are third party editors for Xine playlists that are better than
>> the built-in editor.
>>
>> Nick


Three things

1. I would always prefer to transcode to avi any files before joining
2. Generally I would avoid using cat as you lose timestamps and other
stuff, personally I would just avidemux for the joining
3. In avidemux if your dealing with multiple files its always a good
idea to build vbr time map after each join (audio->build vbr time map



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