[FFmpeg-user] 2 pass seg faults if audio codec not specified in pass 1

Carl Eugen Hoyos cehoyos at ag.or.at
Sun Jun 15 16:52:06 CEST 2014

Sean Darcy <seandarcy2 <at> gmail.com> writes:

> > If the segfault gets fixed, you get an output file but
> > no indication that it is broken

This seems wrong, x264 prints a message at the end that 
the number of frames did not match between first and 
second pass.
I fear that most users will ignore this messages (that 
indicates a completely broken two-pass encode) though.

This is discussed in ticket #2846 but it is not easy 
to read there.

> ffmpeg -y -i input -c:v libx264 -preset medium -b:v 555k 
> -pass 1 -an -f mp4 /dev/null

> ffmpeg -y -i input -c:v libx264 -preset medium -b:v 555k 
> -pass 1 -c:a libfdk_aac -b:a 128k -f mp4 /dev/null

This looks better, you can check if the passlog files 
are different to confirm my suspicion.

Carl Eugen

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