[FFmpeg-user] mix 2 mp4 audio only

[Carl Eugen Hoyos]

Madovsky <infos <at> madovsky.org> writes:

> > Madovsky <infos <at> madovsky.org> writes:
> > 
> >> ffmpeg -i "rtmp://server/app/live1 live=1" 
> >> -i "rtmp://server/app/live2 live=1" -i 
> >> -filter_complex "[0:0]pad=682:450:21:105[left]; 
> >> [left][1:0]overlay=341:105; [0:1][1:1]amerge" 
> >> -shortest -y output.flv
> >> 
> >> but as I use filter_complex I can't use -acodec copy 
> >> to avoid decode encoding audio/video
> > 
> > Yes, this is correct.
> > 
> >> and also amerge above create 2.4 s latency between 
> >> the first and second stream (if I remove amerge it's ok).
> > Sorry if you already answered this:
> > Is this problem (that there is an additional latency) 
> > also reproducible with two files as input?
>
> no, it's reproducible only with rtmp inputs

If you don't use amerge but remux the audio streams 
into separate mov streams, does the resulting file 
show the desync if you change streams at playback?
ffmpeg -i rtmp... -i rtmp... -map 0:1 -map 1:1 
-acodec copy out.mov

Carl Eugen