[FFmpeg-user] Non-mandatory audio

[Greg Oliver]

On Wed, Oct 14, 2020 at 10:40 AM Will Boba <w_boba at hotmail.com> wrote:

> On 10/14/20 11:18 AM, Greg Oliver wrote:
> > sorry just realized I had to redirect stderr to get the results
> >
> > On Wed, Oct 14, 2020 at 10:17 AM Greg Oliver <oliver.greg at gmail.com>
> wrote:
> >
> >> On Tue, Oct 13, 2020 at 8:50 AM Mar Andrés López <mar.andres.l at gmv.com>
> >> wrote:
> >>
> >>> Dear all,
> >>>
> >>>
> >>> I am using the following command to generate dash content from a file:
> >>>
> >>>
> >>> ffmpeg -i video.mp4 –r 25 -c:v libx264 -c:a aac -b:a 128k -ac 1 -ar
> 44100
> >>> -map v:0 -b:v:0 2M -map v:0 -b:v:1 145k -map v:0 -b:v:2 365k -map 0:a
> -f
> >>> dash dash.mpd
> >>>
> >>>
> >>> But sometimes I have streams with audio and sometimes not. Is there
> >>> anyway to make this command to not break if the video file does not
> >>> contains audio?
> >>>
> >>>
> >>> A lot of thanks
> >>>
> >> Assuming you are scripting this, probe the file first and check for
> >> audio.  Use a separate ffmpeg command line for eac result.
> >>
> >> ffprobe <infile> | grep "Stream.*Audio"
> >> if [ $? -eq 0 ]; then
> >>      ffmpeg command with audio
> >> else
> >>      ffmpeg command without audio
> >> fi
> >>
> >
> > ffprobe <infile> 2>&1 | grep "Stream.*Audio"
> > if [ $? -eq 0 ]; then
> >      ffmpeg command with audio
> > else
> >      ffmpeg command without audio
> > fi
> > _______________________________________________
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> >
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>
>  From here: https://ffmpeg.org/ffmpeg-all.html
>
> "To map the video and audio streams from the first input, and using the
> trailing ?, ignore the audio mapping if no audio streams exist in the
> first input:
>
> ffmpeg -i INPUT -map 0:v -map 0:a? OUTPUT"
>
Even easier :)  Nice to know this exists.



>
> Will.
>