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

[Sean Darcy]

On 06/15/2014 09:53 AM, Carl Eugen Hoyos wrote:
> Sean Darcy <seandarcy2 <at> gmail.com> writes:
>
>> If I try to transcode mts in 2 passes using "-an" I
>> get a seg fault:
>
> You are lucky.
>
> If the segfault gets fixed, you get an output file but
> no indication that it is broken in the sense that two
> pass encoding did not make the encoding better (quality
> wise) but worse.
>
> Do not use -an (and use the same container as for
> pass 2) for the first pass.
>
> Carl Eugen
>

Here's the 2 pass example from https://trac.ffmpeg.org/wiki/Encode/H.264 :

ffmpeg -y -i input -c:v libx264 -preset medium -b:v 555k -pass 1 -an -f 
mp4 /dev/null && \
ffmpeg -i input -c:v libx264 -preset medium -b:v 555k -pass 2 -c:a 
libfdk_aac -b:a 128k output.mp4

Should this be changed ? To:

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 && \
ffmpeg -i input -c:v libx264 -preset medium -b:v 555k -pass 2 -c:a 
libfdk_aac -b:a 128k output.mp4

I'm happy to do it.

sean