merge audio with video and volume customization

[pawaom]

merge audio with video and volume customization

I am trying to merge audio and video using following command

String[] complexCommand = {"-i",STORE_DIRECTORY,"-i",yourRealPath,"-filter_complex","[0:a]aformat=sample_fmts=fltp:sample_rates=44100:channel_layouts=stereo,volume=0.5[a1];[1:a]aformat=sample_fmts=fltp:sample_rates=44100:channel_layouts=stereo,volume=0.8[a2];[a1][a2]amerge,pan=stereo:c0<c0+c2:c1<c1+c3[out]","-map","1:v","-map","[out]","-c:v","copy","-c:a","-vcodec","-shortest",filePath};

but it gives me an error Unknown encoder '-vcodec'

How ever when I simply try to merge the audio and video without any change in volume it works fine

can you suggest a proper command to merge audio with video and volume customization

I am referring to this https://superuser.com/a/714991/724432

[YenRen]

Have you solved the problem?