[FFmpeg-user] FFmpeg DASH Optional Adaptation Set

[Mar Andrés López]

Dear All,


I am using the following FFmpeg command for dash generation,


ffmpeg -i video.mpeg -preset superfast -r 30 -vcodec libx264 -acodec aac -b:a 128k -ac 1 -ar 44100 -map v:0 -b:v:0 1500000 -s:v:0 768x432 -map v:0 -b:v:1 750000 -s:v:1 640x360 -map v:0 -b:v:2 500000 -s:v:2 512x288 -map 0:a? -f dash -adaptation_sets "id=0,streams=v id=1,streams=a" -utc_timing_url manifest-mpd.


Currently the manifest is creating an empty adaptation set for videos which do not contain audio:


<AdaptationSet id="1" contentType="audio" startWithSAP="1" segmentAlignment="true" bitstreamSwitching="true"></AdaptationSet>


I thougth that by using -map 0:a? i would make it optional but it is not the case. As you see above the adaptation set is still created.


A lot of thanks,


Best regards.

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